Thursday, January 31, 2008

1. Nikon Flash - Two Separate Metering Systems



After several years of using the SB800 with my Nikon D200 while shooting weddings and events, and after writing numerous posts about this on the Nikonians Speedlight Forum , I decided to consolodate my thoughts in this blog.

Note: I use the term TTL to mean the same thing as iTTL throughout this blog.

Look at the two pictures above. Notice that the first one appears as though the subject is in a cave. The background is black. But the second one has noticeable detail in the background. This blog post is about being able to adjust between these two extremes at will.

Flash photography is a pretty complex subject, and you have to study it a while to understand it. It is also a very rewarding subject and leads to much better pictures in many situations.

The first concept to wrap your head around is that when you take a flash picture it is actually a combination of two exposures; one from available light (also called ambient) and the other from flash. Already you may be able to see intuitively that flash photography will be easier in the dark, because the contribution from ambient is zero! This concept is critical to understand.

And, it is also probably intuitive that if the ambient light is bright, things can get a lot more difficult as you try to balance the two contributions to the image.

So, Nikon made things much easier for us by developing their camera and flash metering systems - these are two completely separate systems that are used together or separately, depending on how we set up our camera/flash.

So let's look at the simplest situation first; a dim room where there is only a little ambient light; like what you would find in a typical indoor home setting at night. If you take a picture in such a setting without flash, in one of the auto modes, say A mode, a typical aperture/shutter would be about f/4 and 1/4th sec at ISO 100.

Now, put the camera in manual mode and increase the shutter to 1/80th sec and leave the aperture at f/4 and shoot another shot. The picture will be very very dark - to the point that the image is barely discernable.

Now, turn on the flash in TTL mode and shoot that same shot, leaving the shutter at 1/80th and the aperture at f/4 (still in camera manual mode). You will see that whatever is in the center of the frame will be properly exposed by the flash. This is because the flash metering system handled the exposure and added just the right amount of flash power to get a proper exposure. It still may not be exactly the right exposure for other reasons, but I'll discuss that in a future blog entry.

Now, place a subject (a person is perfect for this) relatively close to the camera (say 5 feet) with a background behind the subject (say about 15 feet away), still in typical home indoor lighting. Make sure the subject is in the center of the frame and shoot a flash shot in straight TTL (not TTL-BL) leaving the camera settings at f/4 and 1/80th sec. You will find that again the subject came out properly exposed, because the flash metering system handled the exposure. But the interesting thing is that the background behind the subject is back to being very dark, just like in the shot without flash. This is because the flash power decreases very quickly from the distance of the subject to the background and it barely brightens the background at all.

Now, decrease the shutter speed to 1/10th sec and shoot again. The background will be brighter, but the subject will be the same brightness as before. Also, the subject will be sharp, but the background may also show some motion blur, because 1/10th sec is too slow to hold the camera perfectly still (unless you use a tripod). Since the flash was primary on the subject; ie, the ambient was overpowered by the flash, and the flash duration is normally faster than 1/1000 sec, the subject will be sharp with no motion blur.

This shows you that in a dim room, the flash exposure of the subject is controlled by the flash metering system and the background exposure is controlled by the settings on the camera. You can adjust them separately! This is the key behind using the flash in TTL mode and the camera in Manual mode.

Even when the ambient lighting is a little brighter than this, you can still use this technique if you stop down the camera aperture enough to make the flash the primary light on the subject, which takes the ambient light out of the equation. But then your background becomes dark. And if you try to brighten it by decreasing the shutter speed, then the bright ambient light will begin to affect the subject brightness too, and you begin to risk overexposure of the subject. In this situation, shutter, aperture, and flash power all affect the brightness of the subject. It's usually best to simply live with a dark background in this situation and make sure the flash is primary on the subject.

Now, if you are in bright ambient light (like outdoor in daylight), it is simply too bright to be able to take the ambient out of the equation by stopping down the camera, so now you have to balance the flash and the ambient. If the flash contribution to the shot will be less than the ambient contribution, then it is called Fill Flash. When there is a lot of ambient, the background and subject are no longer able to be adjusted independently, and camera manual mode becomes difficult to use. This is when you want to switch the flash to TTL-BL and the camera to one of the automatic modes (S, A, or P). The camera will then measure the ambient light to set its aperture and shutter and send this information to the flash, after which the flash metering system will set the power of the flash to make the subject the same brightness as the background.

If the ambient is extremely bright, like direct sunlight, then it's usually best to select P or S mode (and TTL-BL), so the aperture will automatically stop down to avoid overexposure. In A mode, the shutter will increase to reduce the exposure, but it will be limited by the flash sync speed of 1/250th (D200) and that is often not high enough for bright light if a wide aperture is selected.

One caviat for TTL-BL: the subject must be darker than the background for TTL-BL to work properly. The flash can only brighten the subject to balance it with the background; it can't make the subject darker. If the subject is brighter than the background to begin with, then you probably are best off not using flash. However, there can sometimes be slight shadows on the subjects face that can be 'lifted' with a very slight amount of flash in TTL mode.

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302 comments:

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Anonymous said...

A really, really useful blog.

Keep 'em coming (with as many examples as you can muster!)

Russ MacDonald said...

Thanks for the nice comment!
Russ

Anonymous said...

Russ,

Your “Nikon CLS Practical Guide” write up for the Nikon SB series Speedlight is superb. If your write-up came in the box with my SB-600 or my D80, I would not have spent so much time on the web trying to clarify information contained in the Nikon User Manuals.

Nikon did not take the time to explain the interaction of the camera and flash systems that make up CLS, i-TTL and i-TTL BL. Without the additional information you provided, one would need to spend hours experimenting, as you did, to fully understand the interaction of the various flash and camera settings.

Your explanations are clear and make it easy for one to understand how the camera settings, flash setting and lighting situations are processed for “i_TTL” and “i-TTL BL” exposures and the impact they have on one another.

Thanks for taking the time to consolidate this great paper.


lovelowrey

Russ MacDonald said...

lovelowry,

Thanks for the nice comments and the inspiration to keep adding to this blog.

Russ

CindyS said...

I'm so glad I found your blog. I can't wait to read what else you have to say! Thanks for sharing what you've learned with us and making it easier to understand.

Russ MacDonald said...

Cindy,

Thanks for the nice feedback. I'm glad it is helpful to you.

Right now the wedding business is pretty slow, so I have lots of time, but Easter marks the start of the busy times, and I won't have much time for studying things Nikon from then until the end of the year.

Russ

Anonymous said...

This is the most wonderful resource, as I set out to master my new speedlights. You've demystified something complex for me.
Thank you, from Melbourne Australia.
- Jeremy

Russ MacDonald said...

Jeremy,

Thanks for the nice feedback. If anything needs more explanation, please let me know.

Russ

Mark said...

Really great articles. I just recieved my sb800 a couple of days ago and was finding some of the concepts very confusing. You did a really excellent job of making a complex subject easy to understand. Please do keep posting!

Russ MacDonald said...

Mark,

I appreciate your feedback. Please let me know if there are areas of the Nikon CLS that need more detail or clarifications.

Thanks,

Russ

Anonymous said...

Russ, your blogs are great for a beginner who is totally baffled by the whole Speedlight and camera adjustements that Nike really does a poor job of explaining. Your articles are very enlightening.

Russ MacDonald said...

Thanks! Let me know if something's still not clear.

Russ

Michael said...

Hello Russ,

Thank you so much for this blog. I just read these comments of yours and they are very very clear and informative.

Quick question - at the end you say it is better to shoot in P or S with TTL-BL because camera will revert to 1/250 of a second. I was under impression the whole idea of -BL is to match the ambient. Correct me if I am wrong.

Once again, thank you for this extremely informative blog.

Michael

Russ MacDonald said...

Hi Michael,

You are correct that the reason for TTL-BL is so that the flash will match the ambient. The flash metering system does this by first analyzing the brightness of the background from the metered data from the camera. Then it adjusts its power to make the subject the same brightness as the background.

So, to say it another way, the camera metering system controls the background exposure, and the flash metering system controls the flash power to match the subject to the background.

Now the reason I suggest using with P or S when shooting fill flash (TTL-BL is only for fill flash) is easiest explained by example. Go outside and try this.

Given:
- bright daylight
- ISO 200
- TTL-BL on the flash to fill the shadows on a person's face and to brighten the face to match the brightness of the background.
- A mode and f/3.5 so you can minimize depth of field.

This is all good in concept, but it won't work! Try it

Aim at your subject and shoot. The result will always be a totally blown out image from extreme overexposure.

Why?

Because the shutter speed that is needed with f/3.5 on a sunny day is typically around 1/3200th, but the camera limits the maximum shutter to the flash sync speed speed of 1/250th.

Obviously, if the correct exposure called for 1/3200th and instead you used 1/250th, the result is going to be total blow out.

Now, switch the camera to P mode. Instantly, the camera metering sets up around 1/250th sec shutter speed and f/11. The small aperture is the key! The camera controls the exposure with the aperture, because it can't raise the shutter any higher when the flash is attached.

That's why I say it is much easier to simply use P mode.

One negative thing you may have noticed. When you shoot fill flash, you have to give up narrow depths of field. You have to use small apertures. You simply have no choice.

Please let me know if this helps.

Russ

beareos4 said...

Russ,

Is the two meter approach the reason why the camera meter shows a very underexposed setting when using aperture priority with sb800 on camera in iTTL in your dimly lit room experiment? IS there any way to get the in camera meter to take into account the on camera flash and the settings you have programmed in? Thanks

Russ MacDonald said...

beareos4,

No, the reason the camera always shows an underexposure is that the shutter is limited to 1/60th second. 1/60th sec is too fast for a low ambient condition, even when you have a fast lens of f/2.8. In fact the correct shutter would be around 1/4th sec.

The camera always meters the ambient. The flash metering is self-contained within the flash computer, and it has no effect on the camera metering.

So, the real question is, why would the camera limit the slowest shutter to 1/60th? Well, the reason is that when the light is dim, you do not want it to contribute to the exposure of the subject, because then any motion of the subject or the camera would appear as ghosting. 1/60th is usually chosen, because that it generally accepted as the slowest shutter speed that a normal person can hold it steady enough to avoid camera motion blurring.

However, if you really want the shutter to go more slowly, like on a tripod, for instance, all you have to do is switch to 'slow sync'. Then, the shutter will go as slow as it needs to to allow a normal exposure from the ambient.

I hope this helps.

Russ

beareos4 said...

Russ,

Thanks for the clarification on the metering. This is very good information. I have spent many hours reading different forums looking for a clear explanation of this subject and yours has been the most helpful. I have book marked it in IE. Thanks very much for sharing. Steve O'Sullivan (beareos4)

Russ MacDonald said...

Steve,

You are quite welcome. It has taken me quite a long time to figure this all out and my hope is to save others that same hassel. Once you fully understand the Nikon Flash System, it makes it much easier to make consistantly good flash pics.

Russ

Pedro Oliveira said...

Hi Russ,

Great stuff you put together here. It is the first time I read a total explanation of how the flash system works. I am now reading it again from the start as I found that to be able to apply all this in the field, one needs to understand it inside out.

Maybe I am missing something but in your example above, where you say to use a shutter speed of 1/10 to brighten up the background, shouldn't this be more something like 1/50? Since ambient light is correctly exposed at 1/25, using 1/10 will give an over exposed motion blurred shot with no extra light from the flash.

Thanks,
Pedro

Russ MacDonald said...

Hi Pedro,

Thanks for the feedback.

I'm not sure where you got the 1/25th second shutter, but I think that paragraph 8 (not counting the note) explains that the normal exposure for dim indoor ambient is somewhere around 1/4th second at f/4 and ISO 100.

As an experiment, put your camera in A mode with f/4 and ISO 100 selected, and let it tell you what shutter would be required for a dim indoor ambient condition (typical incandescent lighting). I think the camera will choose somewhere around 1/4th sec.

So, when shooting flash shots, the required speed of the shutter to light the background always depends on the brightness of the background, the f/ stop, and the ISO. In this case the background was very dim, and I normally like to light the background about 1 or 2 stops underexposed, so 1/10th is about 1.5 stops underexposed.

I hope this helps. Please let me know.

Russ

Russ MacDonald said...

Hi Pedro (again),

I forgot one thing.

If your camera indicates 1/25th second for the correct exposure, then you are in very bright ambient light, and in that case I would increase the shutter to about 1/100 sec if shooting flash to underexpose the background by 1 to 2 stops.

Sometimes I underexpose the background by up to 3 stops in order to emphasize the subject a little more.

Also, you mentioned blur. As I said in my blog, the subject will be sharp due to the flash, and a little blur in the background is fine.

Russ

Pedro said...

Russ,
Thanks for your reaction, it makes perfect sense. I see where I went wrong: I saw 1/4 second, did the arithmetic and mentally recorded 0.25 which then got translated in my brain to 1/25 second.

Cheers,
Pedor

Raymond said...

I must say it is one of the best explanation to the Nikon CLS flash system!! Just one quick question though, how to decide when to use TTL flash mode vs TTL-BL flash mode? In a room with dim lighting, is it ok to use TTL-BL?

Russ MacDonald said...

Raymond,

Thanks for the compliment!

The general rules:
1) Use TTL indoors in dim ambient
2) Use TTL-BL outdoors in bright ambient.
3) Between these extremes (like indoors during the daytime with light coming in from outside), you have to make a shot by shot decision.

I always look at the background, and if there is anything bright back there (like a window), I use TTL-BL. If the background is dark I use TTL.

Russ

Raymond said...

That's a very useful tip, will definitely keep that in mind, thanks Russ!

Remi said...

I've been using SB-600 since 2006 and today I fully understand the meaning of TTL-BL flash. Nikon never explain how TTL-BL works and it takes someone else to do for them. Thanks for the great explanation. Keep it coming.

from Malaysia

Russ MacDonald said...

Remi,

It's always nice to get this kind of feedback!

Thanks,

Russ

Vinay Gupta said...

hi russ

finally something that will help me get the hang of my SB-800.

Keep clicking ..
Vinay

Russ MacDonald said...

Hi Vinay,

I'm glad my article helps. The flash takes lots of time to fully understand, but it is very rewarding.

And I'll definitely keep clicking!

Thanks,

Russ

sir_siano said...

i bought my sb800 several months ago and the user manual provided by nikon is of little help for me to correctly expose my subjects in both low-light and brighthly-lit background situations. your CLS guide is heaven-sent and i always refer to it first before going to a shooting assigment.

thank you, Russ, for sharing your expertise.

Russ MacDonald said...

sir_siano,

You are most welcome! I'm glad my blogs help you!

Thanks,

Russ

Michael said...

Howdy Russ

I've shared this blog with 3 other Nikon shooters. Excellent content and thank you for sharing your experience/knowledge. I'm also pursuing the 2nd career as a photographer but not quite finished with the first.

To the point:

Will I get the same exposure results when bouncing the light (with flash in TTL, camera in manual mode, use the FV lock, and shoot in low ambient light)...as I would when shooting directly?

For example...if I attach the trapezoid shaped material promoted at "abetterbouncecard dot com" to my SB800 (in order to experiment with the various angles of light)
will the SB800 still be able to manage the flash exposure with reasonable accuracy?

Thanks for your time.

Anonymous said...

kudos to your entire postings. hat's off to you. what is now missing in my understanding of the sb800 is how A and AA works with respect to the metering modes. i figure you could save me a month on the internet, only to get bad info :-) appreciate any help. thanks in advance

Russ MacDonald said...

Hi Michael,

Thanks for the nice comments about my blogs!

Yes, you will get the same basic exposure whether you bounce or use the flash aimed directly at the subject.

Of course, these two exposures will look different, because the light will be coming from different directions. This can cause some common parts of the image to be exposed differently when compared to each other, but the overall image will have the same exposure either way.

This is very dependent, however, on the flash being strong enough to overpower the ambient light. If the ambient light is too strong, then the flash may have enough power to overpower the ambient when in the direct mode, but not have enough power when bounced. In this case the two images will not be exposed identically.

One other thing that you didn't ask about is the aperture. It doesn't matter what aperture you select (within the power limits of the flash). The exposure will always remain the same. Of course the depth of field will change.

As far as modifiers like the better bounce card, it doesn't matter what you do to the flash. You will always get the same exposure if the flash has enough power to do it.

This is the beauty of the wonderful TTL system! You can bounce, modify, adjust aperture, or shoot direct, and the TTL metering system simply automatically sets the power of the flash to give the same reflected light from the subject in the center of the frame. The only caveat (to repeat myself) is that the flash must have enough power to do what it is being asked to do, and the ambient light must be dim enough so as not to cause any effect on the image.

Once the ambient light is bright enough to affect the image, you have to switch to a mentality of fill flash instead of flash primary. That's a whole other subject.

I hope this helps,

Russ

Russ MacDonald said...

To Anonymous,

Thank you, as well, for the kind feedback!

You're right. I have not mentioned the A and AA modes in any of my blogs. I guess this was because I have never considered them as part of the Nikon CLS (Creative Lighting System). However, on further thought I guess they are simply extensions of the CLS.

So, you have now inspired me! I will write a new blog about how these two modes work!

Thank you for your input,

Russ

delphine said...

Just want to say thank you for you very well explained blog!!!

Russ MacDonald said...

Delphine,

I appreciate the nice feedback.

Thanks, Russ

Kane said...

Great blog to read! Thanks a lot!
One little question. Instead of choosing P or S to get the speed slower like 1/250, can we add a 3 stop ND for such problem in order to enable us to use wider F stops? That will make similar effect like 1/2000 with a narrow DOF right?

Russ MacDonald said...

Hi Kane,

Thanks for the nice feedback on my blog.

And you have a good idea there!

Yes, using a Neutral Density (ND) filter will effectively reduce the ambient light from the camera perspective and allow you to use a wider aperture to achieve correct exposure. The wider aperture will preserve the narrow depth of field you really want.

I never thought of this because I shoot weddings, and there would never be time to install the ND filter. However, under many other circumstances, there would be time to do that, so it should work just fine.

Also, in case it may not be obvious to others reading this, the ND filter will cause the flash to increase power automatically, and the proper fill will be achieved up to the maximum range of the flash. Of course, the maximum flash range is reduced just like when stopping down the aperture, so you have to be closer to your subject than normal or the flash will not be powerful enough to provide the fill you want.

Thanks,

Russ

Kane said...

Thanks for the extra information.
I did not think about ND will also reduce flash effectiveness. You are right, to a real case like wedding, we just don't have time to screw up ND and then take it off for the next shoot. Beautiful scenery just don't wait.
Thanks again!

leesia said...

I was just directed to your blog from the flickr strobist group and it is awesome!!! I have always been scared of my speedlights so I'm really looking forward to poring through this. Thank you so much for such a readable guide!

Russ MacDonald said...

Leesia,

Why thank you very much for your kind words! I'm glad you find my blog helpful.

Please ask questions if something is not clear.

Regards, Russ

secondwind05 said...

hey russ,

just come across your blog by accident - while in another nikon forum. just wanna let you know that i really find this very informative. these are the things i really wanted to learn since i got my sb800 a few months back. i just finished reading your first entry & i already learned so much. many thanks for taking time out from your busy schedule & sharing these things with us. again, many thanks & more power. i'll keep on reading & i hope you don't get tired of sharing...

nicol

Russ MacDonald said...

Hi Nichol,

I appreciate your nice feedback!

And I don't think I will ever get tired of posting about this subject.

Russ

Anonymous said...

Russ

I've read the full blog and had many ah ha! moments. Now I know what FV means and, more importantly, discovered how useful it is in practice. Many thanks on a fantastic job.

Alistair

Russ MacDonald said...

Hi Alistair,

Thank you for the nice feedback!

I had many of those 'ah ha' moments myself as I figured out this stuff on my own. It's really too bad Nikon doesn't put this information in the manuals.

I'm happy to hear that my work has helped you out.

Russ

cnxc323 said...

Man.. I've been using my SB-600 wrongly since I got it more than a year ago..
I used to think that the TTL-BL mode will set the flash output so that it would be the achieve the most ideal balance between the subject and the background.. At least that's what I got from the lousy manual. Coz of this I never bothered using the TTL mode. No wonder I never am satisfied with my flash-ed images.
Many thanks for starting this blog and I shall put this newfound knowledge to good use.

Russ MacDonald said...

cnxc323,

Thanks for your nice comment!

However, the flash user's manual is actually correct. The TTL-BL mode does balance the subject to the background. The problem is that the manual leaves out a lot of additional explanation that is required to use TTL-BL properly.

TTL-BL is designed for when the subject is darker than the background, like in most outdoor daylight shots, and especially in all backlighted shots. Then, the flash increases the brightness of the subject to equal the background. This is commonly called 'fill flash'.

However, if the subject starts out brighter than the background, like in most indoor shots, TTL-BL will still try to balance the subject with the only means it has - flash power. It will lower the flash power in a futile attempt to balance the already brighter subject to the darker background, which is of course impossible, so it will leave the whole image at the brightness of the dark background. This is why you get many dark images when you use TTL-BL indoors.

Thanks again,

Russ

John Fore III said...

Russ, I'm kind of late to your blog and want you to know that you have taken a 500lb gorilla off of my back!!! Nikon should add a link to your blog on the cover of the flash manual for people like me. For the first time I'm feeling confident about my SB-800. Once again Thanks Russ.

Russ MacDonald said...

Hi John,

Don't worry; you're not late!

But I'm not sure what to do with your gorilla! :)

Thanks for the nice feedback, and stay tunred. I have several more articles I am working on.

Russ

Tony D said...

Great Blog Russ. I'm thankful to you for your clear and easy to understand article on the Nikon Speedlights and CLS. I look forward to reading all your future articles.

Russ MacDonald said...

Hi Tony,

Thanks for the nice feedback. I have about 15 articles posted already, and I am working on several more as time permits.

Russ

Anonymous said...

In short,thank you,thank you,thank you...Now I can say that I understand the concept.

Russ MacDonald said...

To Anonymous,

Thank you! I'm glad my blog has helped!

Russ

Matt said...

Russ,

I'm not sure you've touched on exposure compensation yet (at least, I've not run across it if you have).

From what I gather, with the Nikon system, if you dial in -1 EC in the body, you need to dial in +1 EC on the flash. -2 in the body, +2 on the flash. I've read where with Canon, this isn't the case. You can -1 or -2 EC in the body and eTTL takes care of it from there.

Have you experienced this and if so, can you touch on it?

Thanks,
Matt

Russ MacDonald said...

Hi Matt,

Yes, I have already written about how camera compensation works with the flash in thgis article: http://nikonclspracticalguide.blogspot.com/2008/02/5-study-in-camera-compensation-when.html

Also, please be very careful with your terminology. In the Nikon system, it is called 'iTTL'. Canon calls it 'eTTL' which is not the same and works differently.

Let me know if that covers what you wanted me to cover.

Russ

Matt said...

Thanks Russ.

"...Also, please be very careful with your terminology. In the Nikon system, it is called 'iTTL'. Canon calls it 'eTTL' which is not the same and works differently..."

Exactly, which was question was about. With Canon's eTTL (as in my post) you dial in +/- compensation in the body and the you don't have to adjust the flash. With Nikon's iTTL (or so I've been told) when you dial +/- compensation in the body, you then have to dial in the opposite +/- on the flash.

Thanks for the pointer to your previous article. I will head there now.

Thanks!

Russ MacDonald said...

Matt,

Sorry, I didn't read your post closely enough and missed that you mentioned Canon.

Russ

Anonymous said...

Hi Russ,

I'm one of your instant and very grateful fans. :-)

I have a question though. In trying to achieve the negative space effect with the background almost pitch black, I've noticed that the distance between the subject and the background is a very big factor.

Is there a way/settings to still get the same effect if there are some nearby objects that are close enough to the object to reflect light coming from the flash?

I made some tests where I first turned off the flash and I got a very dark exposure so I would say that the camera settings should have been enough to cancel out all ambient light. But when I turn the flash back on, I get reflections from those nearby but immovable objects.

Any advice?

Russ MacDonald said...

Thanks for the nice feedback!

Yes, the distance between the flash and subject is critical. It sets the brightness of the flash assuming you are using TTL mode. If the subject is close, then the flash power is set very low

Also, since the flash power decreases as the sqaure of the distance, anything farther from the flash (like the background behind the subject) will get dark very quickly the more distance you leave behind the subject.

You mentioned that you already have the ambient very dim. This will eliminate all the ambient from the image, leaving the background black, but it won't help with nearby objects.

If there are objects nearby that you want the flash NOT to light, you don't have many options, since the flash power will be much stronger the nearer you get to the flash.

One option is to 'flag' the object. That's when you have an assistant or use a light stand to hold a large square of black fabric between the flash and the object in order to cast a shadow on it.

Another idea is to place your flash closer to your subject on a stand so that it doesn't cast any of its light onto the nearer object. Then, you fire your flash using the Commander in your camera.

Hope that helps,

Russ

Anonymous said...

Russ:
Great overview and easy to understand explanations. I am new to flash and just bought a SB900. I know the principles will be the same as with the 800, but do you plan to make any "refinements" in settings, etc. appropriate to the 900. Thanks for your help. You must have some teaching experience because of the logical way you communicate.

Russ MacDonald said...

To Anonymous,

Thanks for the very nice comments!

At the moment, I don't have any plans to buy an SB-900, so I won't be able to offer any specific advice for that model. However, I believe that they are essentially identical except for the user interface and the fact that the 900 recognizes when it is attached to a DX camera and zooms farther to account for the crop factor.

Yes, I have taught in the past. I taught engineering and math at USF while I was working on my Masters degree in Electrical Engineering in 1975. I also am an FAA Certificated Flight Instructor, and I substitute teach math and science at the high school.

Please let me know if there is anything unclear in my blog.

Russ

Anonymous said...

I posted a question on the Strobist Flickr group and was referred to your article. It's one of the clearest and most useful explanations I've read - thank you so much for taking the time to write it.

Russ MacDonald said...

To Anonymous,

Thanks for the nice feedback! I hope you find all my blog articles useful.

Russ

MRD said...

Hi Russ,
I just found a link to your page from the Strobist group at Flickr and I REALLY appreciate your explanations. You are great at explaining the fundamentals and then building from there. Really appreciate your sharing this with us. I am just getting back into photography, after many years away from it, and the whole off camera flash area is really interesting to me, but still working on the learning curve. Thanks for your help!
Mark D.
San Francisco, CA

Russ MacDonald said...

Hi Mark,

Glad you found me! And thanks for the nice feedback!

Stay tuned!

Russ

Anonymous said...

This is just so useful. When I first got my D300 I thought it was faulty and even took it back to the shop to test. It was only by reading this blog and reading the camera manual several times that I worked out that in Matrix mode the built in flash uses i-TTL BL. Of course using this as a default meter setting I got underexposed pictures indoors. Now I have an SB 600 that gives me more control and consistently good results indoors using straight i-TTL and matrix metering.

I really wish Nikon had better instructions - it should still be possible to use a camera like this out of the box! PAUL

Russ MacDonald said...

To anonymous,

Yes, Nikon makes great equipment, but it takes a lot of experimenting to figure out how to use it because of the marginal documentation. One of the biggest problems they have is that the documentation is written by marketing people, and the design engineers who really know the details aren't involved.

I wonder if you have discovered that you can force your D300 internal flash into regular TTL by selecting spot metering?

Thanks for the kind feedback on my blog! I'm glad you find it useful.

Russ

Anonymous said...

Very comprehensive and ease to understand for new flash player like me.
Thank you very much for your time and effort writing this explanation.

I'll keep coming to this blog.

Hanif

Russ MacDonald said...

Hanif,

I'm glad you find my blog useful. Please let me know if anything is not clear.

Thanks,

Russ

Anonymous said...

Hi Russ,
I wanted to make sure I understood correctly a few comments within some of your answers to questions. In manual mode on the camera and TTL on the flash, does the flash take into consideration the aperture one sets on the camera. I am not sure I understand why changing the aperture does not affect the exposure of the subject. For this to be true, the flash would have to adjust output knowing the aperture has changed.

Thanks,
Jeff.

Russ MacDonald said...

Hi Jeff,

Yes, the TTL flash computer (in the camera) knows the f/ stop and it sets the power of the flash to make the subject the same brightness regardless what f/ stop you choose (within the maximum power limits of the flash).

So, when in TTL mode, if you change the aperture, the power of the flash changes to keep the subject at constant brightness.

However, changing the aperture will change the amount of ambient contribution to the image, but when shooting TTL, that normally only affects the brightness of the background, because you normally overpower the ambient on the subject with the flash by a wide amount, so you don't see much effect on subject brightness as the aperture is changed.

If you are shooting where the ambient is contributing significantly to the brightness of the subject, then changing the aperture will cause some change to subject brightness as well as major changes in background brightness.

Hope that makes sense,

Russ

Jerry Bui said...

Hi Russ,

Should I also set the Flash Shutter Speed to something slow like 1/15 when shooting in manual, or will it adjust accordingly? BTW, I also notice that I can't switch to SLOW as one of the flash options when in M mode.

Thanks,
Jerry

Russ MacDonald said...

Hi Jerry,

The purpose of Flash Shutter Speed (FSS) is to keep the shutter speed high enough for handholding when using the camera automatic modes A and P.

Consequently, FSS cannot be set to less than 1/60th (on my D200). You can set higher, but not lower.

However, you can override the FSS by selecting Slow or Rear Sync. Then, when in A or P, the shutter will automatically go down to speeds that will allow the background to show brightly. However, if you do that while handholding the camera, the background will have lots of motion blur.

In M and S modes, the camera doesn't control the shutter - your do. That's why FSS is not in effect in those modes.

Also, Slow cannot be selected when in M mode, because all Slow Sync does is allow the shutter to go to slow speeds. But if you are in M mode, you are controling the shutter manually. The camera doesn't have any control. You can still set Rear Sync in M mode, because that just tells the flash to fire right before the curtain closes.

Example: Low ambient light, like indoors at night. When shooting family pics, the shutter will sit on 1/60th all the time if you use A or P modes. If you want a lower speed, you can switch to Rear or Slow Sync to have the camera set it automatically for you, or you can set the camera to M or S modes and you set it to whatever you want.

I use M mode in low ambient conditions (like in a restaurant or at a party) and normally set the shutter to 1/80th to reduce background blurring because I am handholding.

Remember, when in low ambient light, the flash controls the exposure of the subject. That's why you can use M mode and set the shutter and f/ stop to anything you want, and the subject will always be the same brightness. The shutter and f/ stop control the background brightness.

Hope that helps,

Russ

missS said...

Thank you so much for taking the time to even put into writing your hard learned experience in this.

The example of this you gave
Given:
- bright daylight
- ISO 200
- TTL-BL on the flash to fill the ---

I was using it the other day before i came across your blog. I was shooting on a very bright day to fill in flash on a tiny subject about a feet away from the camera. I tried and i tried and i tried..about 20 times LOL. every shot was overexposed and frustration mounted.

Now I understand. i've tried to read up and stuff but its seriousl a very difficult subject. For now, at least i understand one and it makes a difference to me. Thank you for helping the clueless "flashers" out there. thank you!

Russ MacDonald said...

Hi MissS,

I've been there!

Controlling Fill Flash is one of the most difficult things to learn in flash photography. Too much and it blows out the shot, and too little doesn't get rid of the shadows. Nikon's TTL-BL helps a lot with that in bright ambient conditions, but you still have to understand the bit about the shutter being limited to 1/250th. That's why I always recommend a new fill shooter use P mode on the camera until they fully understand what is going on. Incidentally, at my studio we joke that 'P' mode stands for 'Professional' mode, since we all use it when we have to go quickly from indoor shots in a dark church to outdoors in bright daylight and don't have time to fool around with camera settings.

I'm glad my blog has helped.

Russ

missS said...

I've printed out this page since you dont have a book (yet) and its like 37 pages long (lol)...the questions posted by readers and your answers were all so priceless too!
Most importantly you tried to explain as simply and dont make it intimidating for one to ask. Some forums can be very intimidating.

, thank you again Mr Russ MacDonald..

Russ MacDonald said...

MissS,

Thanks! I appreciate the kind words!

Russ

Paul said...

Hi Russ,

I haven't got a flash unit yet, I planned to but was a bit put off from experience borrowing my friend's SB-800 unit. I was totally frustrated and clueless on how to use it. Your articles and your answers to the questions posted here has been most helpful in every way. Thank you so much!!

Now i have no doubt to get myself a flash unit and to have fun exploring the possibilities with it.

Paul

Jenni said...

I recently made the mistake of not resetting my ISO and was shooting at ISO 400 in Aperture Priory mode with a Nikon SB600. The photos were very noisy and I put it down to the ISO. Am I correct in thinking this caused the excessive noise?

Thanks for all the time you put into this wonderful Blog.

Russ MacDonald said...

Hi Paul,

Yes, be sure to get the flash! Once you learn how to use it, you'll love it!

Thanks for the nice feedback!

Russ

Russ MacDonald said...

Hi Jenni,

ISO 400 on a modern DSLR should not be too noisy. If you look closely, you can detect noise at ISO 400 on your computer screen, but it is not normally visible in a print.

Use of the flash doesn't affect the noise.

To minimize noise at any ISO, expose to push the pixels in the histogram toward the right edge.

Russ

Paul said...

Hi Russ,

There's something I don't understand yet about using speedlight on nikon..

Pardon me for the bad english but here goes, when you use the flash unit wirelessly(TTL mode) via commander on the camera body, do you have to point the flash unit sensor(on the front side) to the subject(ie: in the middle), in order to get a correct flash exposure? If say i wanted bounce the flash or there are two units of wireless flash, does all the strobes sensor has to point to the subject in the TTL mode?

Much appreciated,

Paul

Russ MacDonald said...

Hi Paul,

Your English is fine!

The sensor on the flash itself is not used when using TTL.

The Remote flash fires its monitor preflash, and the reflected energy is measured by the sensor in the camera. Then, the Commander on the camera sends the calculated flash power back to the flash, and after that tells it to fire.

Another important thing to know is that the reflected energy from the monitor preflash is metered by the camera in the center weighted frame. That's why it is important to make sure the subject is at least partially centered. If the subject is way off-center at the edge of the frame, use FV Lock and recompose.

Russ

Paul said...

Wow that's such a fast response from you. Thanks Russ!!! That last bit of Nikon wireless flash system clears it up for me!!

Thank you very much Russ!!

I'm definitely getting myself a flash unit soon, saving up for one.

In the meantime, I'm going to borrow my friend's SB-800 to practice(Manual flash too), and ofcourse I'll keep checking your wonderful blog regularly to read and understand better if I have missed/forgot some points. I've also suggested your wonderful blog to my friends to read.

Cheers,

Paul

Russ MacDonald said...

Hey Paul,

I'm glad I could help, and thanks for the kind feedback!

Be sure to read the questions and answers after each blog for additional information that I have not yet included in the initial post.

Russ

hkf said...

hi Russ, i benefit a lot from your article, may i raise a question about the example shown shooting at 1/10s, the subject will be exposed correctly without blur while the background has a little blur due to the flash duration is normally faster than 1/1000 s.

i had shot night portrait at shutter speed 1sec, but both the subject and background blurred a lot, why did the subject also get blurred with the flash duration faster than 1/1000 s?

the exposure time of the blog example is 1/10s, how can the bacground exposed at 1/10s, while the subject exposed at 1/1000 s? in my understanding, the entire pic including the subject and background should be both exposed at 1/10s instead.

i know my understanding is probably wrong, please feel free to correct me.

best regards,
Ho

Russ MacDonald said...

Ho,

First, you are thinking correctly. If the background is exposed for 1 second, so is the subject. I think I should have explained myself better.

My comments refer to a scene where the subject was much much darker than the background. In this case, if I left the flash OFF, the 1/10th second exposure left the subject so extremely underexposed, that it could be treated as though the subject wasn't exposed at all by the ambient light. The background was so much brighter than the subject that the 1/10th second exposure allowed the background to appear bright and the subject black.

Then, when the flash was turned ON, the subject was exposed entirely (almost) by the flash, while the background was so far behind the subject that the flash made no effect on it. The square law tells us that the flash power decreases exponentially with distance. If the distance from the camera to the subject is say 6 feet, then 6 feet behind the subject the flash power is already down to 1/4th the power. At 24 feet, the flash is down to 1/8th power. In this case, the waterfall was about 48 feet away, meaning the power of the flash was down to 1/16th power, which is insignificant and provided no visible brightening.

In your night portrait where you were using the 1 second exposure with a flash, the motion blur of the subject means that the ambient light was strong enough to significantly expose the subject during the 1 sec shutter. This points out why it is really important to always check the ambient first. To do this, turn the flash OFF and take a test shot at the shutter speed and aperture you plan to use to be sure the ambient light is not significantly exposing your subject. The key word is 'significantly'. If the subject shows very dark in the image, that's OK. There will be no blur when the flash is turned on. Then the flash will provide all the significant exposure on the subject.

Please let me know if that helps,

Russ

hkf said...

thanks for your clear reply, i did the test of dark subject with flash at shutter speed even down to 4 seconds, the photo still turns out to be sharp. the result amazed me a lot,

in my past knowledge, handheld for 4 seconds is unbelievable to be sharp, but the test did.

Russ, you help me a lot and i learn a lot from you.

best regards,

Ho

Russ MacDonald said...

Ho,

It's really quite amazing isn't it?

I'm glad I could help you!

Russ

Raymond said...

I'd believe the key point here is that the subject is in a much darker position compared to the background... I once made a group shot of <10 people in a small private dining room in a restaurant and I was amazed at the power of the flash (SB-800) gave me; all the subjects and the background were correctly exposed -- all from a single flashgun!! :)

Russ MacDonald said...

Hi Raymond,

The SB-800 is indeed a powerful flash for its size.

However, the darkness doesn't increase the power of the flash. It just keeps the ambient from causing ghosting if the subject (or the camera) happens to be moving.

Also, in a restaurant environment, the flash is usually not used to light the background. The ambient is normally used for that. In fact, you usually try to keep your subject well away from the background, especially walls, to avoid flash shadows.

In a studio, you may place your subject near the background and let the flash illuminate both the subject and the background, but normally you use a separate light for that purpose.

I have shot very large groups with two SB800's. Have you read my blog on that subject?

Russ

Raymond said...

Thanks for your tips, Russ! That shot was made in a small room so I bounced the light off the wall and I was quite satisfied with the result; and yes, I have read all your blog articles and learned so much from them; I'll keep revisiting them when I need to refresh my memory. Thanks so much for sharing you in-depth knowledge & experiences on using the Nikon flashguns!!

Russ MacDonald said...

Hi Raymond,

I'm happy to help! Let me know if there is anything that is not clear.

Russ

Ogniancho said...

Great work!

Russ MacDonald said...

Hi Ogniancho,

Thanks!

Russ

Anonymous said...

Thx for your great post!!
I really learn a lot from what you write!!
I really appreaciate what you did!!


After reading your post, I have a question, can you help me?

From your post, I know that the strength of the main flash from the speedlight is determined by using pre-flash, and it only depends on Aperture and ISO, right?

How about this case:
In ambient light
M mode setup 1/30 f/3.5 ISO 800
and still under 2EV
then we need to use flash to let the subject has correct exposure.

What if I set the shutter to 1/60?
Since shutter faster, that mean the subject becomes less bright,(if there is only ambient light)
What TTL will do in this situation?

(1) since ISO, Aperture no change, then TTL no change

(2) Since the subject is dimmer than b4, so the speedlight will shot a brighter flash to compensate the loss in order to achieve a correct exporsure.

Which one is correct?
(in the question, I want to assume the effect of ambient light cannot be neglect)

Thank a lot !!!!!

Bubble Lee

Russ MacDonald said...

Hi Bubble,

One very important concept to understand is that when using regular flash sync, the entire flash pulse takes place during the time the shutter is open. That means that changing the shutter speed will not affect the amount of flash contribution to the image.

Also, for any of the assumptions to work, you always have to make sure the flash makes a much greater contribution to the exposure of the subject than the ambient does.

Changing the shutter speed will always change the ambient contribution to the image, because that light is constant, and the longer the shutter is open, the more of it will contribute to the exposure.

So, in the case that you described, where you changed the shutter from 1/30th to 1/60th, the flash contribution to the image won't change, but the ambient contribution will increase by one stop.

As long as the ambient is low, the flash will have a much greater impact on the subject than the background. This means that if you change the shutter speed from 1/30th to 1/60th, the increase in brightness of the subject due to the ambient will be very small, and often undetectable. Of course, the brighter the ambient, the more effect the shutter will have on the subject.

The background brightness is the thing that changes the most when you change the shutter, because the flash loses power so quickly that in the background the ambient is the primary contribution and the flash is secondary.

Then you mentioned TTL. All my discussion uses TTL. If you don't use TTL, then the aperture will affect the flash contribution. When TTL is used, changing the aperture doesn't affect the subject (again assuming ambient is negligible), because the flash power changes to compensate.

Lastly, you asked about when the ambient light is bright enough that you cannot neglect it. If this is the case, then you now have a much more difficult situation, and none of the comments I have made above are true. When the ambient light is bright enough to significantly affect the subject, then changes of shutter speed will change the brightness of the subject as well as the background. The background will still be affected more than the subject.

When I run into this situation, I simply increase the flash power to overpower the ambient, so all the assumptions will work again.

This situation normally only causes a problem outdoors in daylight conditions. Then, the daylight is so bright that you cannot increase the flash enough to overpower it, and you have to use a 'fill' flash concept. It is very rare when shooting indoor flash that you cannot increase the flash power sufficiently to overpower the ambient, so that you can once again control the background and subject independently.

Hope that helps,

Russ

Anonymous said...

Thank for your answer!!!!

Because I am busy these days, I just read your reply today.

I think I understand your answer, and try to do an experiment.

I use TTL, fix aperture and ISO,
and set the shutter to 1/200, let the overall exprosure under 3ev.

Then I increase the speed of my shutter step by step from under 3EV to 0EV. (Each step 1 stop that mean I take 10 photos).

I find that the brightness of the image are nearly the same!

In this case, does it mean the power of the flash is much stronger than ambient light?
OR TTL do sth to adjust the power?

and my last question:
If in the situation that ambient light is too bright, we cannot neglect their effect, you said that we should increase the power of flash. I not sure the meaning. It means:

(1) decrease the shutter speed to let ambient light becomes lesss bright. (then flash is obviously brighter)

(2) increase the output of flash
(then the object over exprosure?)

many and many and many thx!!!!!!

Bubble

Russ MacDonald said...

Hi again Bubble,

One thing that has not been mentioned: Everything I have written assumes you are using regular flash sync and not High Speed Sync. If you are using High Speed sync, many of my answers would have been different. I recommend you fully understand regular flash sync before trying Auto FP High Speed Sync mode.

Yes, in your experiment the brightness of the subject did not change, because the power of the flash was much stronger than the ambient. You should have seen a change in the background brightness, however, because the shutter affects the ambient portion of the exposure, and the background is usually lit by ambient only.

TTL does not change the power of the flash when the shutter is increased.

Regarding your last question: (1) is correct. Reducing the ambient by increasing the shutter leaves the flash the same while decreasing the ambient, so it 'increases' the percentage of flash on the subject. But you will see the subject getting darker, because of the decreasing ambient. This is what you want, because in TTL mode, the flash doesn't take ambient into account, so it will usually overexpose the subject until you take the ambient away with the shutter.

However, bright ambient conditions is why TTL-BL was invented. This mode will automatically adjust the flash power to balance the brightness of the subject with the background. Whenever I shoot flash in bright ambient situations, like outdoors in daytime, I always switch to TTL-BL.

You never mentioned whether you were using the pop-up flash. I have been assuming you were using an SB600 or SB800 external flash attached to the hot shoe. The pop-up flash always works in TTL-BL mode when Matrix or Center-Weighted metering is selected. It always works in regular TTL if you select Spot metering. Since TTL is usually best indoors, you should select select spot metering for indoor flash when using the pop-up flash.

Russ

Anonymous said...

"regular flash sync and not High Speed Sync. If you are using High Speed sync, many of my answers would have been different. I recommend you fully understand regular flash sync before trying Auto FP High Speed Sync mode."

I afraid I don't understand what you are talking about...
Any information for me to reference? thx~

Bubble Lee

Russ MacDonald said...

Bubble,

I don't know which camera you have, but every camera has a shutter speed called the 'Flash Sync Speed'. On my D200 that speed is 1/250th.

There is a choice in the menus to select Auto FP Sync. Don't select it until you understand more about it.

When in normal sync, the camera cannot go above the flash sync speed. Then, all of the things I have told you are true.

High Speed Sync will allow the shutter speed to go above 1/250th and some of the things I told you are no longer always true.

I wrote another blog on High Speed Sync here: http://nikonclspracticalguide.blogspot.com/2008/03/10-auto-fp-high-speed-sync-explained.html

Russ

Anonymous said...

I don't know how to express my heartfelt appreciation to your help!

I will read all the information and try to understand more about flash~!!

My cam is D80 and I use SB600 usually and sometimes pop-up flash for casual photo.

I have read the blog about built-in flash. Why you are so sure that TTL-BL in matrix and TTL in spot metering? Any hard envidence? or just comes from your experience?

Before I read your blog, I always use pop-up flash together with matrix metering. But I can't find and problem about the brightness on the object. But when I use FV lock, I usually find that the object is too bright. is it related to what your metion about pop-up flash?

Bubble Lee

Russ MacDonald said...

Hi again Bubble,

Here is a way you can test this yourself:

Camera OFF
Mount SB-600 in hot shoe
Camera and flash ON
Camera in Matrix metering
On the SB-600 select TTL-BL mode

Now, change your camera to spot metering mode and look at the display on the SB-600. It will have changed to regular TTL. TTL-BL is never available when in spot metering.

However, on the SB-600 you also have the option of selecting regular TTL when in Matrix mode, if you want to. This is what I use most of the time for indoor shots.

However, on the pop-up flash, there is no option to select TTL or TTL-BL. It simply defaults to TTL-BL when in matrix metering and TTL when in spot metering. It tells you this in the camera manual.

If you shoot with TTL-BL indoors, it will work most of the time, but some of the time it will underexpose. If you use regular TTL indoors, you never have the underexposure problem.

TTL-BL was designed for bright ambient conditions like outdoors in daylight.

Also, refering back to my previous post, on your D80, the flash sync speed is 1/200th. So, when the camera is in regular flash sync, the highest shutter speed you can select is 1/200th. You can change the sync mode to Auto FP (high speed sync) using menu item 25, but I recommend you not do this until you understand more about your flash and camera.

Russ

Anonymous said...

I love U man!!

I will recommend all my fds which are interested in taking photo to visit your blog!!

I really learn a lot!!

Bubble Lee

Felix said...

Russ,

Your blog is definitely a standard which Nikon should include in their web site as an official source of reference. You pull so many points together which is what learning is all about, associations and connections, making it easier to retrieve from long – term memory. Great Blog! Keep it flowing... and of course we all look forward to the "book". :)

Russ MacDonald said...

Hi Felix,

Thank you for the compliments!

As far as a book goes, that sounds way too much like work!

Instead, I think I'll just continue to write articles about particular topics that add to the books that are already out there.

Russ

Yuval Feder said...

Dear Russ,

I've discovered your blog just three days ago and I've read it twice (only this chapter...) already. As many guys and girls who bought their camera I've bought the SB-600 as well, but never understood all the functions it offers. You have brighten my life as a beginner photographer.

Thanks a lot!

I have a question, I hope it is not stupid...

When I shoot with TTL BL mode, do I need to point the head of the SB-600 directly to the pace of my object or fire to the ceiling to avoid shadows?

Thanx a lot from Israel.

Russ MacDonald said...

Yuval,

Thanks for the nice compliment!

When you shoot TTL-BL mode, you can point the flash anywhere you want to. In fact, in any TTL mode the flash power calculation is done based on either reflected power from the subject or the distance to the subject or both. You can always point the flash head anywhere you want to, and the subject will come out exposed the same - as long as you stay within the flash power capabilities. Obviously, if you aim the flash backwards, and none of the light hits the subject, you will run out of flash power and the subject will be dark.

Also, in TTL-BL (and NOT regular TTL) when you point the flash head straight forward, the distance information reported by the lens is partially used to determine the flash power.

However, TTL-BL only works correctly in bright ambient light, like outside during daytime. TTL-BL was designed for adding fill to a shot, not for supplying the primary light.

TTL-BL makes the flash power equal to the ambient brightness. It is great for when the subject is BackLighted (which is where BL came from in the first place).

If you use TTL-BL in low ambient light, like indoors at night, you can get unpredictable results. Often the shot will come out too dark, but it can be highly influenced by specular highlights in the background (like reflective surfaces, windows or lights).

Indoors, in dim ambient light, (or whenever you want the flash to be the primary light) it is always better to use regular TTL. Then, the flash will expose the subject to a 'standard' brightness, without consideration of the ambient light. In regular TTL mode, watch out in bright ambient light. The flash exposure will add to the ambient exposure on the subject, and it will often overexpose the subject. That's when TTL-BL is very useful.

Hope that helps!

Russ

jgm.jansen said...

Russ, just found your blog today and it trigger me enough to start using my SB600 again.

Thanks for your effort to put this material together.

Jan

Russ MacDonald said...

Hey Jan,

Glad you find my work useful!

Thanks!

Russ

Anonymous said...

Thank you so much for this write up. But I don't thank you for the fact I have been playing with my camera and flash for 45 minutes instead of going to bed because you gave me so much useful information!!!!

So many things to try tomorrow...gnight!

Russ MacDonald said...

To Anonymous,

Thanks for the nice feedback!

Now get some sleep! :)

Russ

Kati said...

Hallo Rus, You say "If the ambient is extremely bright, like direct sunlight, then it's usually best to select P or S mode (and TTL-BL),"
Why P or S and why not MANUAL?
Usually is always Manual metering your choice.
gr. Kati

Russ MacDonald said...

Hi again Kati,

Manual mode will work just fine if you have the time.

It takes quite a bit more time than any of the auto modes to get your camera set right. Especially when shooting quick grab-shots of moving people in bright light.

My comments in this blog are about how to shoot fill without ending up with unexpected overexposure due to the shutter being limited to the flash sync speed (1/250th).

If you are shooting in camera A mode, indoors, in dim ambient light, and you move outside into the daylight and keep shooting moving people all the way, you have to remember to switch to some mode that will allow the aperture to stop down, so the 1/250th limit won't get you. Manual will allow this, but it is slow and you will miss lots of great shots fiddling with your aperture and shutter.

P mode solves this problem very nicely.

I don't know a single wedding photographer who would make the transition from the church to the outside, following the B&G, using camera Manual mode. It just slows you down too much.

Russ

Anonymous said...

Hi Russ,

thanks a lot for explaining the working of the different options of our Nikon flashes. It was more understandable than the normal userdocumentation of Nikon. Maybe they can hire you ;-).

I've taken a lot of testshots but I'm left with some question. Within a week we have a wedding of friends and they asked if I could take some pictures of their evening-dinner. Normally I like pictures where the ambient light is also captured somehow. Before my present camera (Nikon D60 + SB600) I usually took pictures without the flash (with flash persons were correctly illuminated, but the background was dark or you really saw at the picture that is was taken with flash (very white and looking "cold" that way). Off course it resulted in many blurry pictures of the guests (I do not like really "posed" pictures so the people are talking, moving their heads, arms etc).
So please, could you maybe give me a hint which parameters I could use to take nice sharp pictures without ruining the normal ambient light in the dinner-room by overexpose it or underexpose it?
Thank you very much in advance.

Erik (Belgium)

Russ MacDonald said...

Hi Erik,

My usual settings for flash shots at a reception are 1/80th shutter, f/3.5 - f/5.6 (depending on depth of field needed), and ISO 400. Then, I set the flash in TTL mode at -0.7 ev (or so). The actual setting on the flash depends a lot on your particular camera and the brightness of the ambient. You have to experiment with this and figure out what the correct flash setting should be.

In normal reception my settings will make the background somewhat dark, but still with lots of detail.

The more ambient light you allow into your pictures, the more difficult it becomes to avoid overexposure on the subject. Remember that the flash system sets its power assuming that there is zero ambient lighting the subject. Therefore, if you slow the shutter ('drag the shutter' or use 'slow sync') to allow lots of ambient, you have to also turn down the power of the flash even farther.

Using f/5.6 also darkens the background significantly, so most of my shots are at f/3.5. I sometimes use f/2.8, but that makes the depth of field so narrow it is hard to keep even a single subject fully sharp.

Hope that helps,

Russ

John Meyer said...

Great blog!

von said...

Great blog! Thanks :)

There is nothing mentioned about the setting for the metering. The BL doesn't work when the camera is set to spot or center metering. How do you set up the camera indoors?

Russ MacDonald said...

Hi Von,

TTL-BL works in both Matrix and Center-Weighted metering. However, it works best in Matrix metering.

I have discussed this in several of the Q&A's after the blogs. I probably should update the blogs themselves to include this.

Indoors the camera should be set to regular TTL and Manual mode. I wrote about this in several of my blogs.

Russ

Anonymous said...

Russ:
A general question about the speedlites.

In ALL the articles and videos I've seen so far about portrait lighting, the photographer ALWAYS uses the studio lites.

CAN you use, say 2 or 3 speedlites instead of the studio lites?

I thought of adding 2 SB-600s to my SB-900, and putting Gary Phong LS-IIs on all 3.

What do you think of that for 3-point portrait lighting?

Thanks for all the great information....
Rick Hollingsworth

Anonymous said...

Russ:
An observation about using ND filters to reduce DOF in low light.

One of you subscribers (and you) mentioned that there is not enought time doing a wedding to "put on" an ND filter.

I came across this idea the other day.

Instead of taking the time to screw on an ND filter, my firend just carries a couple of 4x4" Conkin type ND filters. When he needs one, he just pulls it out of his picket, sticks it infront of the lens, and fires away.

Then, just stick it back and keep on shooting.

Just an idea....

Rick Hollingsworth

Russ MacDonald said...

Hi Rick,

I am actually working on a new blog discussing this very point.

Yes, you can use speedlights in the studio. In fact, that's exactly what I use in my own studio!

I have used studio lights in the past, and the only advantage they have over speedlights is power. However, high power is not usually required in the studio, and you can work much more quickly (lots more poses), because you can set the power on all the Remotes from the Commander without the need for a light meter.

I typically set my key and fill speedlight to the right and left of the camera in umbrellas, and about half the time, a third speedlight with a snoot as a hair light. This uses up all the groups that are available in the Nikon wireless CLS system.

I use commander TTL for the key and fill lights and commander manual for the hair light. This makes it very easy to set a desired lighting ratio and bring a touch of hair light to taste.

However, you must also realize that the power ratio of the two lights is not the same as the lighting ratio, since they add where they overlap, but that is a whole other subject.

Then, I sometimes use a continuous lamp as a background light with a daylight bulb to match the speedlights.

You also asked about using a Gary Fong Light Sphere on each flash. I wouldn't do that. I recommend using a diffuser on the Commander in order to scatter the command pulses in all directions giving better wireless operation, but umbrellas work much better than the LS on the Remotes.

Hope that helps,

Russ

Anonymous said...

Russ:

Thanks, good info. Too much scattering from the LS-IIs? Since one seems to work so well, thought 2 or 3 might also work well. Guess not.

Thanks for the insight.

Rick

Russ MacDonald said...

Hi again Rick,

No, it's not that there is too much scattering from the LS's.

The reason is that most studios are painted black, or at least are dark colored, to reduce bouncing, which makes it possible to have exact control of the light on the subject. If you are bouncing, you have limited control of the lighting ratio.

So, when shooting in the studio, you want minimum bouncing and soft controlled light at the same time. That is usually done with umbrellas or soft boxes. Then, you can set specific lighting ratios and make truly professional portraits.

Russ

Anonymous said...

Consequently, FSS cannot be set to less than 1/60th (on my D200). You can set higher, but not lower.

Russ:

On my D80, the selections for FSS go from 1/60 DOWN to 30s. Am I reading this right? Mine seems to go DOWN from 1/60th, NOT up???

Huh??

Rick

Russ MacDonald said...

Rick,

There are two shutter speed limits related to flash. The Flash Shutter Speed is the LOWEST speed the shutter can go to, and the Flash Sync Speed is the HIGHEST speed the shutter can go to.

The Flash Shutter Speed is normally set at 1/60th and is usually in play indoors in low ambient light. The purpose of the Flash Shutter Speed is to keep the background from showing motion blur when handholding.

The Flash Sync Speed is 1/250th on the D200. This is the maximum shutter speed that the flash can sync with. This speed limit is reached most often when outdoors in bright ambient light shooting fill flash. This speed limit can be set lower in the D200 menu but most people leave it at 1/250th. In fact, I have never found any reason to ever set it lower.

Hope that helps,

Russ

John Meyer said...

Hi, Russ

So you're working on a topic for using Speedlights in the studio?

Now that I can't wait to read!

With your experience and brilliant content on your other 15 topics, this new one can't help but be a winner!

When d'you think it'll be published?

Kind regards

John

Anonymous said...

Russ:

Let me just cut to the chase....

We just got back a few weeks ago from a vacation at WDW in Orlando.

We stayed at the Grand Floridian, and booked a portrait sitting with the Disney photographer there at the hotel.

The photographer shot about 30 pics, both inside and outside of the hotel.

On ALL shots, he used a D40, 70-200 f/2.8 VR, SB-800, and the GP LS-II (Cloud - with dome)

ALL of his shots came out perfect - good exposure of us AND the soft focus background. Very nice.

Since then, I have tried (in vein) to reproduce those shots at home.


Now, for me....I have the D80, 70-300 VR, SB-600, and the same LS-II as he used.

I TRY to shoot manual, when possible, because everyone on the net says you need to do that....no other reason.

Yesterday, I took about 30 shots of my daughter - outside - golden hour - sun over my back - with the LS-II.

No matter where I set the camera and/or flash, the pics all came out bad. Either she was overexposed and the BG was fine, or, she was fine and the BG was dark.

Really frustrating!

So, if you were using my gear, shooting her in those conditions, how would you do it?

Sorry for the long post, but had to describe my technique as best I can.

Thanks again,
Rick Hollingsworth

Russ MacDonald said...

Rick,

There are lots of variables. Don't listen to people who say you have to shoot manual. Manual is right for some flash shots, but it makes others much more difficult. You should use the camera mode that makes the most sense for the situation.

Before you can even think about the camera mode, you have to answer two critical questions: 1) Will the flash be Primary or Fill? and 2) Should you use FP Sync or regular sync?

If you don't know what I am talking about then you need to read my blogs - all of them. I explain what all these things are and how to set the camera to use them.

After that, you can decide whether to shoot in camera manual mode or one of the automatic modes.

Just as a point of reference, I shoot professionally, and I use all camera modes, (A, S, P, and M). It all depends on the situation.

Once you understand the details in my blogs, you will be able to take perfectly exposed pictures just like the Disney Photog.

If you will send me an email, I will be able to give much more information to you. I don't like to use the Q&A area of my blogs for lengthy discussions.

Email follow-up comments to russ@russmacdonaldphotos.com.

Russ

uhjb said...

Russ,

After discovering your site, read and learned from the messsages for the last few days, I've learned more than I ever have for the last few years regarding flash photography using Nikon flashes. Thank you for all your time and effort to help people like me and so many others that like to learn but not knowing where to get such good source of information.
That's one thing I'd like to confirm with you in regards to something you've suggested. There are times Ineed to take pictures in door when I don't have my SB600 with me. As you've have suggested that in order to be able to set the on camera flash to i-TLL, "Spot" metering should be used. Does it mean I probably should always use "Spot" metering when "fill-in" flash is not needed while shooting in door? Is that a good assumption?

Thanks,
uhjb

Russ MacDonald said...

To uhjb,

Thank you for the nice feedback!

When using TTL indoors, the choice of camera metering is usually unimportant. Remember, the camera metering has absolutely no effect on the flash power when using regular TTL.

The only thing the camera metering is used for when shooting in TTL mode is to set the ambient exposure, and indoors most people use Manual mode on the camera which means the camera metering is totally unused in that situation. So, it doesn't matter what mode it is in.

Now, if you are using TTL-BL, then the camera metering mode is critical (Matrix is usually best), because the flash uses that metering data to set its power.

Hope that makes sense,

Russ

Steve said...

Hi Russ, like most people have said here, "THANK YOU"! Truly awesome info here. I have a question I'm hoping you can shed some light on (so to speak)...

How does Auto ISO effect flash use? Am I best to leave Auto ISO on or set my ISO manually? I notice that when Auto ISO is on, when I am metering for the ambient light, the ISO jumps all over the place, then when I flick on my flash it reverts to the set ISO. Does this have any effect on how much ambient light is allowed into the photo (ie if I want to slow my shutter speed to let more ambient in, does AUTO ISO screw that up?)

Thanks again so much!

Russ MacDonald said...

Hi Steve,

Thanks for the compliment!

I have never understood the way Auto ISO works with the flash. As a result, I don't use Auto ISO with flash at all.

I normally shoot in camera Manual mode when shooting indoors in TTL mode. If I were to select Auto ISO, then then the background brightness would change each time the ISO changed. That really looks bad in a series of pictures.

I much prefer to leave the ISO fixed.

Russ

Steve said...

Thanks Russ, that's exactly the problem I've been finding, it's just too hard to keep the ambient consistent.

Thanks again.

Lyn Walkerden said...

Love your blog! Finally I have found an explanation that I can understand as I begin my journey into CLS.

I have one question and forgive me if it has been asked already in the extensive comments. What metering mode is the most effective to use in the examples you describe. I shoot with a D300 and have an SB600 if that makes any difference. I would usually use spot metering when shooting in natural light. Thanks again for the information!

Russ MacDonald said...

Hi Lyn,

Thanks for the nice compliments!

To answer your question requires a bit of discussion.

In this blog I explained that the two metering systems (camera and flash) are separate. The camera metering affects the ambient portion of the exposure, and the flash metering (which you can't change) sets the flash portion of the exposure.

In TTL mode, the two metering systems don't communicate at all. This means that the flash power will be the same regardless of what camera metering method you choose. And if you are using your camera in Manual mode (like most people do when shooting indoors), the camera metering doesn't affect the settings on the camera.

So, when shooting indoors using regular TTL with the camera in Manual mode, you can choose matrix, center weighted, or spot, and it will have absolutely no effect on the images.

However, if you are using TTL-BL mode, then the two metering systems do interact. Specifically, the flash metering looks at the data from the camera metering, and then chooses a power that will make the subject an equal brightness with the ambient. In this case, the best metering mode on the camera is matrix, because matrix provides the best proxy for the ambient brightness that there is. You can use Center Weighted with TTL-BL, but it doesn't work as well as Matrix, because it doesn't look at the whole frame, and may not pick up bright objects on the edge of the frame that change the average ambient and change the power of the flash. Then, if you choose Spot Metering, you will find that TTL-BL is not available, because in Spot Metering, there is only subject brightness coming from the camera metering, so there would be nothing for the flash to balance the subject brightness with.

So, in short: the only time the camera metering affects the flash power is when using TTL-BL, and Matrix is usually the best choice. When shooting regular TTL with the camera on Manual Mode, it doesn't matter, so I personally leave it on Matrix just to be ready for the next time I switch to TTL-BL.

Hope that helps,

Russ
If you are in regular TTL, then the metering mode has no effect on the flash power.

Anonymous said...

Dear Russ,

thank you very much for this really helpful blog. i've learned so much. i'd be really grateful if you would share some tips about using flash with candlelight. what i think works best is to use TTL-BL and about 0.7 ev, but i'd very much like to hear from you

thanks

Beth

Russ MacDonald said...

Hi Beth,

Candlelight pictures are tough, and you have to be very careful not to over-flash them, which removes all the romance and warmth.

In fact, I normally shoot candlelight without the flash, in camera Manual mode using spot metering on the subject. I also normally underexpose by at least a stop to add mystery and romance.

Then, sometimes, if the candle flame looks bad from being totally blown out, I reduce the exposure with the shutter even further and add a very small amount of fill from my regular TTL flash with an orange gel on it (to make its temperature closer to the flame temperature). I start with my flash set to about -2.0 ev and increase it if necessary. The idea is to add so small an amount of gel'd flash that no one can tell from the image that you used flash at all.

Using TTL-BL for candlelight is an interesting idea. I will definitely have to try that!

Thank you for your suggestion,

Russ

Anonymous said...

Dear Rus

thanks so much for your very rapid and very helpful reply. i'd rather not use flash too but sometimes i think there just isn't enough light. i will try your suggestions

thanks again

Beth

Russ MacDonald said...

Hi again Beth,

I agree that sometimes it is so dark that you have to use the flash.

When it is really dark, you have to drag the shutter (use a really slow shutter speed) and rear sync. That will greatly brighten both the subject and the background, but you will probably have some ghosting from motion blur plus the flash will freeze one image. With rear sync, the ghost trails will be on the proper side of the motion blur.

Russ

Anonymous said...

Dear Russ

thanks again, i'll give this a go too

Beth

Christopher said...

I am learning more here in an easier to understand language than the manuals for my sb900 and sb600, thank you!

Russ MacDonald said...

Hi Christopher,

Thanks for the nice feedback!

Now, all I have to do is scrape together the $$$ to get an SB-900, so I can be sure what I am saying about the 800 and 600 also applies to the 900.

Russ

Anonymous said...

Hello Russ,

I've been practising candlelight shots and trying what you've suggested. It's working pretty well - so thank you, but there is still one thing which i don't understand.
the set up is a candlelit dinner. i am using ISO 100 because candlelight is so noisy, 1/200 shutter speed to try to avoid flame ghosting on faces which looks strange, orange gel, flash on TTL bounced at about 60 degrees with a bounce card, as i don't have a large diffuser, and set at about -2.3ev and an aperture of 3.5. this seems to work quite well from a distance of about 4 meters. however, what i don't understand is that when i close the aperture to say f5.6 or f8 the subject and the background get lighter. i would expect them to get darker. please, what am i not understanding?

thanks very much

Beth

BECALM said...

Hi Russ
No words can described the appreciation from me and people read your blog. The time is valuable and you are generously spent to put it in your blog to share with other fellows, even you offered your personal email to dicuss specific questions. I suggest you should create a "donation" button for people who want to show their thankful to you.
As I read your blog many time and now may I have easy short question.
I learned and understood from your blog, there are two meters system flash and camera. If I want to meter the ambient light I have to turn off the flash, I found this to awkward. Is there a quick fix or tip to meter the scene without turn off the flash?
Many thanks from me
Your loyalty blog reader
Brian

Russ MacDonald said...

Hi Brian,

Thanks for the great feedback!

This is very difficult to explain, but hopefully you can look at your camera manual and then read this a few times, and it will make sense. The trick is learning to use the built-in light meter, which is very useful for many other reasons beyound flash photography.

You don't have to turn off the flash to meter the ambient if you use camera Manual mode or Shutter Prioity mode. You simply use the built-in Meter. You will definitely need to study the section on how to read the built-in light meter in your camera User's Manual.

In summary, from camera M or S mode, you adjust the Main and Sub- Command Dials to collapse the meter 'dots' into the center of the display. This is called zeroing the meter, and when it is zeroed, that means the aperture and shutter are set to give the proper exposure for the ambient light (ie, a shot without flash).

For flash work, and leaving the flash turned on, you normally want to set your aperture wide open or around f/4 (which happens automatically when in camera S mode), and then adjust the shutter to underexpose the ambient by about two stops. On the built-in meter, each big mark on the scale is one stop, so you want to adjust the shutter to extend the dots out to the second big mark on the scale on the negative side to select two stops underexposed.

Then shoot.

You can't do this from camera A or P modes, because when the flash is ON, the shutter is limited to 1/60th of a sec, so there is no way to use the light meter to set two stops underexposed.

Hope this makes sense,

Russ

johnhorn said...

Hello, thank you so much for your blog. I am still trying to absorb all that you have written about. I am however confused on one point - that is I set my camera to manual mode set aperture, exposure time and ISO and take a shot where the exposure looks good. I now adjust the exposure compensation dial to -5ev and take a further shot. This new shot is under exposed by 5 stops but the camera shooting data states that the exposure time, ISO and lens f number are unchanged. How can this be? I thank you in anticipation John Horn

Russ MacDonald said...

Hi John,

I think you probably do not understand what changing the camera ev really does.

In Camera Manual mode (with or without the flash), changing the camera ev doesn't make changes to the aperture or shutter.

Adjusting the Camera ev changes the light meter zero point in the camera. It's up to you, when in Camera manual mode, to recenter the meter with the aperture and shutter.

However, changing camera ev will change the ISO if you have Auto ISO turned on. Note: I recommend NOT using Auto ISO with flash. It hasn't ever worked very well the times I've tried it. In fact, I never use Auto ISO at all.

Adjusting the camera ev also does one more very important thing. It changes the power of the flash.

So, when you adjusted the camera ev to -5, with the camera in Manual and the flash turned on, it reduced the power of the flash by 5 stops and that is why your picture got darker.

I previously wrote another blog about this here: http://nikonclspracticalguide.blogspot.com/2008/02/5-study-in-camera-compensation-when.html

Hope this helps,

Russ

Quash said...

Thank you for such a helpful blog. I am saving for an SB-600 or SB-800 to go with my D90. I know you had an SB-800. Have you had a chance to use the SB-600 and SB-900 and do you have any thoughts and comparisons between these three flashes? Still shooting with a D200?

Because I don't yet have the flash to experiment with, I read up to part 4 and have now stopped and am going back and working through the comments. A tremendous amount of information from you in the comments, as well as the articles. They have been very useful in orienting me to the concepts of flash use.

I agree with others. Time for you to take all of this and shape it in to a book. This is such useful and well-written information that it deserves and should be exposed to the widest possible audience.

Kind regards,
Quash

Russ MacDonald said...

Hi Quash,

Thanks for the kind compliments!

I have several SB-600s as well as my SB-800s, and both are great flashes.
They function identically as far as their TTL and TTL-BL functions are concerned. I often use my SB-600s for background and hair lights when in the studio. The only real difference is that the SB-600s have about one stop less power, so the SB-800s are better in umbrellas.

I used my SB-600s for several weddings before getting the first SB-800, and they worked perfectly.

Yes, I still use my D200, although it now serves a backup role to my D3 which I bought for its high ISO capability. I also still take my D70 as a second backup and sometimes a 2nd shooter uses it. All three make extremely high quality images.

Russ

Anonymous said...

Every kudo in this blog is well-deserved and I too greatly appreciate your sharing this knowledge with us.

Question: Does the ttl-bl mode work only when the sb800 is mounted directly on the camera shoe? I cannot get the BL option to work when I use the sb800 off-camera on the Nikon camera bracket amd aux. battery unit connected through a cord to the hot shoe.

Thanks again for your help.

Anonymous said...

To clarify my previous post, the flash bracket is the Nikon SK-6 and it is attached to the camera with an AS-16 cord. I am using an sb-800 and both a D-200 and d-700 on which I am finding no "BL" mode available on the SB-800 when used with the SK-6 and AS-16.

Thanks again for all the information and help.

Russ MacDonald said...

I don't own an SK-6 so I can't check it, but all I have read about it says that iTTL-BL should be available.

Check your camera metering mode. iTTL-BL is not available when Spot metering is selected.

Russ

Taufan Atmanegara said...

increasingly reads your article about nikon CLS, I am more and more understanding about way of using speedlight.

but I still have not understood about how realizing photograph like example of 1 is upper. makes photograph background seen coal black, but photograph object seems to clearly is hit light.

I have done some experiment, but remain to be just cannot perfect. you could probably assist with suggestions.

ugly english language forgiveness. thank before all russ

Russ MacDonald said...

Hi Taufan,

I'm not sure I understand your question, but I will try to answer anyway.

All comments refer to TTL flash (not TTL-BL).

Make sure the background is at least as far behind the subject as the subject is from the camera. If the background is close behind the subject, then the flash will light the background as well as the subject.

To make the background black, increase the shutter speed high enough to eliminate the ambient contribution. Try using shutter speed 1/200th.

If you can't make it go black, then you can also darken the background by stopping down the aperture. Try f/8. However, be careful. When stopping down, the TTL flash power will increase to keep the subject the same brightness, so don't stop down too far or you will run out of flash power. For instance, at f/22 the flash will be at maximum power, but it won't be enough power to properly light the subject, so both the subject and the background will become dark.

Hope that helps,

Russ

Ville said...

Brilliant!

I have suffered a lot with flash photography previously. I have been reading (and practicing the whole evening) the blog. I have really high hopes to capture proper flash photos in the future.

Thanks Russ!

Cheers,
Ville from Finland

ps. I bookmarked your page!

Russ MacDonald said...

Hi Ville,

Thanks for your great feedback!

This is off the subject, but I have lots of fond memories of Finland. I worked on numerous integrated circuit projects during the late 90's in Helsinki, Oula, and Salo for a large Finnish Company as an Electrical Engineer with Texas Instruments.

Russ

Anonymous said...

I found your blog about a week ago after being referred to you from a photo forum post. It is a very informative site. I have a D90 (9 months old) with a brand new SB900. I've learned a lot. I have to take an indoor picture with 25-27 people in it on Christmas Eve. Your most recent blog entry (cookbook) will help a lot in preparing for that family picture.

Quick question..... on this first blog entry you talk about iTTL and TTL-BL. Is TTL-BL available with the D90's built-in flash? I don't see any way to switch to that mode if there is. There could be times outdoors when I want some quick candids without having the SB900 mounted on the camera all the time. I've taken some outdoor pics with the popup flash at a fairly close distance and the exposure seems balanced.

Thanks again for your blog.

Fred

Russ MacDonald said...

Hi Fred,

First, I sometimes drop the 'i' from in front of TTL and TTL-BL, but it means the same thing.

Yes, the built-in flash can work in TTL-BL mode. In fact, TTL-BL is its default mode, and you have to switch the camera to spot metering to force the pop-up flash into regular TTL mode.

I wrote about this in this blog: http://nikonclspracticalguide.blogspot.com/2008/02/8-how-buit-in-flash-metering-works.html

Hope that helps,

Russ

Raymond said...

mister Russ MacDonald,
I have a question about Nikon CLS when the build-in-flash is used as commander. I understand that the flash does fire during the exposure, even when disabled, because it uses visible (not infra red) light to communicate with the CLS Remotes. When taking close-ups this can be very disturbing. What strikes me is that when the shutterspeed is faster then 1/325 this comunication flash is outside the expore. What is happening here.
Thanks very much for your help
regards
Raymond van Houten

Russ MacDonald said...

Hi Raymond,

The Commander (either the built-in flash or an external Commander) communicates with the Remotes using pulses contained within the preflash sequence.

Most Commanders also have a 'Master' flash in them (uses the same flash tube). This Master flash can be turned on or off in the Commander menu. If you turn it off, the Master flash will no longer contribute to the image, but the preflash sequence will still occur as it communicates with the Remotes.

The last pulse in the preflash command sequence is the 'FIRE' pulse. This is the pulse that tells all the Remotes to flash. This pulse occurs right after the shutter opens, and it can contribute slightly to the exposure, but it is a very low power pulse, so the contribution is insignificant in most cases.

The fastest the shutter can sync with the flash is 1/320th, so I don't understand your comment about 1/325th shutter. You cannot set a higher shutter speed than 1/320th UNLESS you have turned on the Auto FP Sync Mode. With this mode turned ON, as soon as the shutter speed is increased past 1/320th, it automatically changes to FP Sync mode. If you don't know what this mode is, please read the blog I wrote about it here: http://nikonclspracticalguide.blogspot.com/2008/03/10-auto-fp-high-speed-sync-explained.html.

Hope that helps,

Russ

Raymond said...

Thanks for the quick reply Russ,
And yes I have switched on this FP high speed sync mode. Shooting portraits in daylight within 10 feet it works well.
But I still don't understand why in this mode, above 1/320 second, the commander flash doesn't show.
regards
Raymond

Russ MacDonald said...

Hi again Raymond,

I don't understand what you mean by "the commander flash doesn't show".

Russ

Raymond said...

Hello Russ,

Using the on-board-flash as commander. This flash shows in the picture: in the eyes at close-up portraits. Until 1/320 seconds. Faster then that the FP high speed sync takes over and the commander flash (from the on-board-flash) doesn't show in the eyes anymore. What is happening here.
thanks
Raymond

Russ MacDonald said...

Hi again Raymond,

Ahhh. Now I understand.

The pop-up flash cannot work in FP Mode, so when you go above maximum sync speed, the pop-up Master Flash stops contributing to the image, but it still works as the Commander at all speeds.

You have to use an external Commander/Master Flash that will work in FP Mode, if you want it to contribute to the image in FP Mode above Flash Sync Speed.

Hope that helps,

Russ

HOBC said...

Hi Russ,

I'm still trying my SB-600 with D90 & I having a hard time getting the correct exposure. I'm confused with setting & always overexpose my subject with the flash.

I have searched at Youtube for any guidance but it wasn't in full information or details. Finally, I found your blog & after reading a few pages. I begin to understand why I confused. Now, I get the idea how it works with my D90.

Many thanks for the your valuable guidance, explanations & efforts.

kevin

Russ MacDonald said...

Hi Kevin,

Thanks for the compliment! I'm glad you find my blogs useful.

Still, it takes lots of practice to be able to hit perfect flash exposures regularly. Keep practicing!

Merry Christmas!

Russ

HOBC said...

Hi Russ,
Wishing you & family a Merry Christmas!

I will keep on practicing to get the right exposure at any situations.

Happy New Year 2010!

Thank you & regards,

kevin

David said...

Thank you so much for your blog!
This is by far the best the best source of info on CLS I was able to find.
In a week I'll be shooting in a nightclub and I'd like to ask you for some tips on using flash in this specific environment.
Pictures will be taken handheld using D700, 24-70 f/2.8, SB-900(on camera). I'm planing to use M mode and shoot mainly with flash.
After having read your blog I've come to several assumptions:

1. ISO
I assume I should set the ISO to a high value let's say 3200 to get most of that nice, colorful ambient light of that place within a reasonable high shutter speed. I also assume I should keep the "auto-iso" ON just in case the camera needs to adjust the exposure while everything else is locked in M mode. IF I should leave "auto-iso" ON then I'm thintking 3200 max iso and 1" for the slowest shutter setting.

2. APERTURE
Keep it @ 2.8 to get most of the light in.

3. SHUTTER
I'm thinking 250 for people dancing and 1/60 for more stabilized ;) subjects. Or maybe 1/2 wouldn't look too bad since I have the flash?

4. FLASH
TTL mode. 250 max flash sync. Bounce if possible. I'm hoping to use it mainly as fill in order not to ruin the ambiance of the place. As far as I unerstand there should be no use for BL and FP in given lighting conditions so keep them OFF.

I realize that people moving fast on the dancefloor in low light and are challenging conditions but I'd like to make the best of it with your advice.

Sorry, if I wrote too much but it's going to be my first gig in a nightclub and you seem to be the most knowledgeable person out there.
Best regards and a Happy New Year!

Russ MacDonald said...

Hi David,

It sounds like you have a fun gig coming up!

Normally I would agree with all you wrote, except for one thing: ISO 3200! That changes everything.

ISO 3200 will make it like you are shooting in much brighter ambient -almost like outdoors in daylight. You are right that at that ISO you will be using the flash for fill and not as the primary light. That makes it much much more difficult to get the flash right when the ambient is allowed to contribute that much.

This means your whole approach has to change from what I have written.

If you use regular TTL when allowing that much ambient into the images, the flash will then add to the ambient and you will risk blowing out your subjects. I normally use ISO 400 in a party situation for the express reason of limiting the amount of ambient that will contribute to the images. This leaves my flash primary.

So, if you decide to use ISO 3200 your flash will become fill rather than primary and it should be better to use TTL-BL. This will let the flash power itself down to match the ambient. And if you use TTL-BL, you should also use camera A mode on f/2.8 and let the camera set the shutter. That will greatly reduce the risk of blowing out the subjects.

Then, the only problem with f/2.8 is that the depth of field is very shallow and focusing is more critical. But the D700 is extremely good at focusing, so if you are careful and use single point focus and lock on the faces of the performers you should get good results.

I would also try a few shots at ISO 400 with regular TTL and in Camera manual at f/2.8 and 1/80th. Those are the settings I would probably use.

I hope that helps! Please come back and let us know how it worked out.

Russ

David said...

Wow! You reply faster than my speedlight :)
OK Russ, I'll try both approaches and let you know how it came out.
Many thanks.

Anonymous said...

Thanks for taking the time to share your knowledge! Greetings from Germany

Russ MacDonald said...

Hi Anonymous from Germany,

My pleasure! Thanks for the feedback!

Russ

Muel said...

Hi Russ,
I am also new to my D90 and SB-600 and also overexpose my subjects. I cut and pasted the entire blog, printed it out, and now will begin reading. I too am hoping to understand how to get the proper exposures, and what the proper settings are. Wish me luck! Will you be adding to this blog with any updated advice?

Russ MacDonald said...

Hi Muel,

I am glad you find my articles interesting!

I add new information to my blogs as I complete it. I have several new articles that I am currently working on, and I will complete them as time permits.

I hope to find the time to complete these articles in the next couple of months.

Regards,

Russ

Anonymous said...

Russ, hi again.
Still playing catch up with all your fascinating articles.
This part has me slightly perplexed, mbe help me out pls?

"Even when the ambient lighting is a little brighter than this, you can still use this technique if you stop down the camera aperture enough to make the flash the primary light on the subject, which takes the ambient light out of the equation. But then your background becomes dark"

IF I wanted a dark background, this would be ideal (Atristic interpretation etc)
However, if I used FV lock, this would no longer hold true, as FV lock adjusts to compensate for aperture or ISO or shutter change.
Am I correct in saying so?
Thanks much

Russ MacDonald said...

Hi Anonymous (wish you would sign your name so I would know with whom I'm talking),

No, FV Lock does exactly the same thing as when you shoot a regular flash shot, except that it stops the sequence right before the shutter is released and holds the flash power calculation in memory.

The main purpose of FV Lock is to allow you to point directly at the subject, fire the monitor preflash to meter the subject, and save the calculated power setting. Then, you can recompose and click the shutter, and the subject will be exposed correctly even though it is no longer in the center of the frame.

Have you read my blog on FV Lock? You will find it here: http://nikonclspracticalguide.blogspot.com/2008/01/4-so-what-is-flash-value-lock.html

Regards,

Russ

Christian said...

Hi, these posts are very helpful. I'm still coming to grips with all of the features of my new D90 and SB-600. I wonder if you could explain how Auto-Iso works in the various scenarios (P/A and M modes; and TTL, TTL-BL)?

Christian said...

Hit "post" too quickly.

...for example, Auto-Iso seems disengaged with the pop-up flash (the default always being chosen, and displayed white in playback), yet auto-iso seems to choose different iso's with the SB-600 (displayed as red in playback).

Russ MacDonald said...

Hi Christian,

No, I'm afraid I can't help with Auto ISO. I don't ever use it, because it does unexpected things when the flash is being used.

Instead, I use ISO 200 and camera P or S mode and TTL-BL for fill flash outdoors in daylight.

I use ISO 400 and camera M mode, 1/80th shutter, and regular TTL for indoors in artificial light.

Russ

Shawn said...

Unbelievably well-written blog, this has been so helpful. Just a practical question, where did you position your strobes to achieve the results on this page? These two shots are wonderfully lit, just trying to figure out positioning. Did you also use a diffuser? Thanks again.

Russ MacDonald said...

Hi Shawn,

Thanks for the great feedback!

Both of these pictures were with a single single flash mounted on-camera.

I haven't written much about using the flash off-camera, because there is so much you can do with the flash on-camera, and I think that should be learned first.

Regards,

Russ

Liz said...

Have you seen the new Nikon D3S?
I recently got it and absolutely love it.
I found a short clip, where the whole video and stills were captured using it. http://vimeo.com/9337388

Russ MacDonald said...

The D3S is a wonderful camera, but I only got my D3 about eight months ago, and I haven't gotten over that sticker shock yet!

Russ

Anonymous said...

Nikon have a new D3S and apparently this video was made using it. Video people! http://vimeo.com/9337388

Mike Le Gray said...

I've just stumbled onto this blog, having clicked the link in your signature on <a href="http://www.nikonians.org>Nikonians.org</a> and I'm very glad I did!

Some very useful information, very clearly stated.

Many thanks for your efforts.

Russ MacDonald said...

Hi Mike,

Thanks for the nice feedback!

If you have questions, please be sure to post them.

Russ

I LOVE YOU said...
This comment has been removed by a blog administrator.
Anonymous said...

Thank you so much for your insight; I have been struggling to figure out my SB-900 with little success.
I am attempting to move from hobby landscape shooting to portraits and weddings and your blog has truly been the most beneficial site I have found.

Rick A

Anonymous said...

Thank you so much for your insight; I have been struggling to figure out my SB-900 with little success.
I am attempting to move from hobby landscape shooting to portraits and weddings and your blog has truly been the most beneficial site I have found.

rick a

Russ MacDonald said...

Hi Rick,

Thanks for the great feedback!

Russ

Anonymous said...

I'm only 8 months into my Nikon DSLR experience (D700/90) and I've taken 99 percent of my photos w/out flash (either using a tripod or boosting ISO, and using manual focus primes); now, I'm moving into flash and want to say that your info is very helpful. There's so much focus on cameras and lenses, understandably so, but if you're doing a wedding or indoor event you really need to master flash ... but CLS is confusing! So, thanks!

Carl

Russ MacDonald said...

Hi Carl,

You're most welcome.

I assume in all my blogs that you already know how to set the camera and flash into the various modes I discuss. If you need help getting the camera or flash into any particular mode, just drop me an email. You can find my email address on my website: http://russmacdonaldphotos.com.

Regards,

Russ

George said...

Hi, Russ
thanks for this articel.
I have a problem to understand this:

When I'm in a pretty dark situation. And I will take the shutter longer) maybe from 1/200 to 1/25 I will make the background 3 steps higher (+3 EV) That's right. Isn't it?

BUT when doing this my Subjekct will be 3 steps higher TOO. So I understand that that the shutter speed will not influence the flash light that falls on my subject BUT than it will be 3 EV to much.
Is this right or not?

Often I find out that the shutter speed has no result on my subjekct. but why? the longer time will brighten up my ambient light AND my subject too.

Not matter wheter taking the picture in Manual or i-TTL Mode the subject ahs to be over exposered. But it is not everytime why?

Why does the longer shutter don't have this effect on my subject?

And last is there a different for the modes Manual, i-TTL and i-TTL standard?
thanks a lot.

Russ MacDonald said...

Hi George,

When you change your shutter from 1/200th to 1/25th, yes, it will make both the subject and the background +3 ev higher.

However, if you are in dark ambient conditions, and you increase in brightness by 3 stops, both the subject and the background will probably still be dark.

You can check this by turning off the flash and taking a picture. It will probably be very dark. This is the ambient contribution.

Then, when you turn on your flash (in regular iTTL mode - NOT iTTL-BL mode), it will set its power automatically to make the subject the standard brightness.

But, the flash power decreases very rapidly after passing the subject, so as long as the background is a sufficient distance behind the subject, the flash will have no effect at all on the background brightness.

This is why the flash power sets the brightness of the subject and the camera shutter speed sets the brightness of the background.

You have to watch out, though, if you slow the shutter to really slow speeds, the ambient will begin to affect the brightness of the subject. Any ambient contribution there is on the subject will add to the flash. This will cause overexposure. This is why you should always make the ambient contribution on the subject insignificant, and always check to make sure you image is dark without the flash. Then, you will not get overexposure with the flash turned ON.

Please read all my blog articles. I discuss the advantages of using camera Manual mode when shooting regular iTTL and camera P mode when shooting iTTL-BL.

Also, there is a 'Flash' manual mode, a 'Camera' manual mode, and a 'Commander' manual mode.

Please be careful to use the appropriate terminology to avoid confusion between these various manual modes.

Russ

George said...

Hi Russ!
Thanks for answering me.
In the articel you wrote:
"Now, decrease the shutter speed to 1/10th sec and shoot again. The background will be brighter, but the subject will be the same brightness as before."
In your example the correct light withput flash would be at f/4 and 1/4sec. so you have increases from 1/80 (5 EVs) and ambient is just 1 EV darker thank without flash.
Why is the subjekct at the same light? (the ambient light has to influence the subject too I think)


And second when using your example for BL mode (ambient really bright) but in A mode and have turn on FP than the shutter will decrease automatic? Or just in P mode?
I think there is no reason to switch off FP.

Or when using M don't I see the recommend expose with the + --|-- - when I look through the camera? (viewfinder)

Why I should nevertheless take pictures in P mode?

Thanks a lot. Your explanations are great.

Russ MacDonald said...

Hi George,

Your comments are all exactly right. I simplified the discussion in this blog to make it easier for beginners to get the correct idea. Your comments and observations about the 5 ev and 1 ev are correct.

However, in my example, the subject was much darker than the background, so normal on the subject would probably be around 1.0 sec. When I decreased the shutter to 1/10th, it did brighten both the subject and the background, but the subject was still so much darker than the background and the flash was so much brighter than the ambient on the subject, that the increase in subject brightness is not obvious. If you were to take one shot with the flash off followed by one shot with the flash on, you probably would see the slight difference in brightness.

The reason for my recommendation to use camera P mode with TTL-BL is to protect you from overexposure, because in camera A mode the shutter speed is limited to 1/250th (flash sync speed).

You can use camera A mode if you are careful to stop down far enough with the aperture to obtain the correct exposure. But this is exactly when P mode does!

You can also use camera A mode if you also select Auto FP High Speed Sync, so the shutter speed can go up to what is needed to control the exposure. But the problem with FP mode is that the flash power is less than half of what it is when using regular flash sync. Even still, FP mode coupled with a wide aperture is a great way to take a portrait in the shade on a bright day, as long as you stay within about 10 feet of your subject.

Yes, of course you can use camera M mode and the built-in light meter for all situations, but you have to know more about what you are doing. The reason I recommend P mode is to help those who may not know as much about this as you do.

Russ

George said...

Hi Russ!
THANK YOU SO MUCH!!
You realy helped me much more than all my books I have read about this theme. (and i have a lot of) ;-)

So when using FP and A Mode for BL the Flash should also know that it is on less power right?
So I just have to be careful about distance. That's true?

Just a last question please.
My D300s has 1/320 as shortest time. Is this true?
One times I asked the Nikon support they told me YES. That's in fact the shortest time I can use to get FULL Flashpower.

But another time (I asked again because I read that much) they told me NO.
They told me that is a step between FP and not FP. At 1/320 it is more flash power than on FP but not the full power (so the flash stars to fire not just one flash.)
So what is true?
AND Can I use 1/320 without disadvantages or shoud I use 1/320.

In the D300s' menu it is listed in a funny way. 1/250 FP or 1/320 FP.
I just think that if there was no difference ther wouldn't be that funny menu.

so there have to be disadvantages to use 1/320.

Or not?

Thank a lot. Again.

Russ MacDonald said...

Hi again George,

"So when using FP and A Mode for BL the Flash should also know that it is on less power right?
So I just have to be careful about distance. That's true?"

Yes, that it true. TTL-BL works perfectly when using FP mode. The system takes care of everything for you. In fact, it is very nice to be able to use FP mode and TTL-BL in camera A mode outdoors to be able to add fill flash and blur the background with a wide aperture. With regular sync, you can't open up the aperture very wide in bright ambient, because the shutter speed is limited to 1/250th (or 1/320th).

"My D300s has 1/320 as shortest time. Is this true?"

Yes, 1/320th is the fastest shutter you can use with the flash in regular sync mode. But that doesn't mean you will get full power. The reason you won't get full power is that at 1/320th shutter, the flash pulse is not quite complete when the shutter closes, so some of the flash pulse is lost. This effectively reduces the maximum flash power that is available. Please read my blog 'When is Full Power Flash Not Full Power?': http://nikonclspracticalguide.blogspot.com/2009/03/15-when-is-full-power-flash-not-full.html

The guy at Nikon apparently did not know much about this, or you didn't understand him correctly.

First, the flash pulse is always continuous, whether in Regular Sync mode or FP Mode. There is a lot of confusion about this, because if you look at the circuitry that fires the flash tube inside the flash, the signal to the tube is pulsed. However, there is enough persistance in the light output, that the flash pulse remains on at all times. However, when you pulse the flash tube like this, the brightness of the light is less than half of what it is when using than regular sync.

In 1/320th FP Sync mode, and with 1/320th shutter selected, the flash fires in normal sync mode (full brightness). The problem is that when the flash is firing at maximum power, the normal flash pulse lasts 6 to 8 ms. They don't tell you about this in any of the Nikon documentation, because about 70% of the pulse power occurs in the first 1 ms. It's the tail that extends out 6 or 7 more ms. At 1/320th sec shutter, the shutter closes after 3.1 ms. This means the shutter closes before a significant portion of the tail of the pulse is completed. This is why the maximum effective power is lower. Also, when the shutter closes, it quenches the flash pulse to avoid wasted battery power.

So, if you use 1/250th FP Sync and you choose 1/320th shutter, then the flash will fire in FP mode. Its maximum power will be about 1/2 of normal.

If you use 1/320 FP Sync and you choose 1/320th shutter, then the flash will fire in regular mode, but you will lose a significant portion of the tail (as I explained above). Its maximum effective power will then be only slightly higher than when in FP Sync.

At 1/250th shutter speed and below, the maximum power of the flash will remain the same, regardless of whether you have selected 1/250th FP Sync or 1/320th FP Sync.

At 1/320th shutter speed and above, the maximum power of the flash will remain the same regardless of whether you have selected 1/250th FP Sync or 1/320th FP Sync.

Hope that helps,

Russ

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