Monday, November 9, 2009

17. Why use Camera Manual when Using Flash Indoors?

I am often asked why you should use your camera in Manual mode when shooting flash in low ambient conditions, and why is that better than shooting in Aperture priority. This study will explain the reasons, plus I will show the effects of Rear Sync versus Front Sync when there is any subject motion involved in flash pictures.

But first it is important to fully understand that when you use your camera in Manual mode and your flash in iTTL, the flash handles the exposure of the subject, as long as the ambient is dim, and the subject is in the center of the frame. So the image is still exposed automatically even though the camera is in Manual mode.

Here are my conditions that do not change during this study:
- Dim ambient light
- ISO 400
- f/2.8

Image 1: Test Image, Flash off, 1/60th, Manual Mode. The purpose of this image is to indicate how much ambient light there is. You can see that at 1/60th, it is about two stops underexposed. When using the camera in Manual mode and the flash in iTTL mode, you want the camera controls to always underexpose the ambient by about two to three stops. Also, I moved my hand, so you can see what motion blur looks like without the flash.


Image 2: Flash ON, Aperture Priority. I was moving my hand toward my face. Look closely at my fingertips. That orange blur on each finger is called ghosting or ghosting trails. The flash froze my moving hand and then the ambient caused the ghosting. Also, noticed the direction of the ghosting trails. The ghosting trails appear to preceed the motion of my hand. This is what we call ghosting trails on the 'wrong' side of the motion. The position of the ghosting trails was caused by using Front Sync.



Image 3: Flash ON, Camera Manual Mode, 1/120th shutter. I was moving my hand toward my face. Notice that there are no ghost trails. This is because the shutter speed was increased high enough to eliminate the ambient from the image.
Image 4: Flash ON, Camera Manual mode, Rear Sync, 1/60th shutter. Again, I moved my hand toward my face. Look closely at my fingertips. Now, you can see ghost trails going in the opposite direction. This is because Rear Sync was used, which caused the flash to fire at the end of the shutter cycle rather than the beginning of the shutter cycle as in the previous images. Now, the ghost trails are on the 'correct' side of the motion.
Image 5: Flash ON, Aperture Priority mode, Rear Sync, 1/15th. Again, I moved my hand towards my face. Notice the much greater amount of ghosting. This is because when you select Rear Sync in Aperture Priority, you also get Slow Sync, and Slow Sync, causes the shutter speed to reduce to fully expose the ambient. This also caused overexposure.

Image 6: This has all the same settings as Image 5. I just wanted to show the great sensitivity to movement. All I did was move my head.
Conclusions:

1) When shooting flash in low ambient conditions, like normal indoor artificial lighting, it is best to use Camera Manual mode with Rear Sync to control ghosting.


2) Using Aperture priority with Rear Sync is not a good choice for dim ambient conditions. It will lead to overexposure and way too much ghosting and general motion blur.

3) Using Aperture Priority is also not a good choice when using Front Sync when shooting in dim ambient conditions, because the camera will always select 1/60th sec shutter (Flash Shutter Speed). This is too slow to stop ghosting during motion like a speaker waving his arms or a couple dancing.

Recommendation:

Always use Camera Manual Mode with Rear Sync when shooting flash in dim ambient conditions so you can control the ghosting.

Never use Aperture Priority when shooting flash in dim ambient conditions, because you cannot control the ghosting.

79 comments:

Anonymous said...

Russ,

Thanks for your great post. I am a bit confused.

1) Looking at the pictures I would've thought that the best choice is Manual Mode + Front Sync, not Rear Sync (due to ghosting)

Yet in conclusion you recommend Manual Mode + Rear Sync ?

2) How do I know which initial settings to set on Manual? Set the camera in P, and then dial the same settings in Manual?

Thanks again for your wonderful blog!

Mark (31, NYC)

Anonymous said...

P.S. Received an O Flash today from Singapore - a knock off of Orbis, Ray Flash Ring Adapter and similar. Price? Cool $43 on ebay, including S&H.

http://www.flickr.com/photos/nelsonlai/3525978272/

http://cgi.ebay.com/Macro-O-Flash-Ring-for-Nikon-SB800-D700-D3-D2-D1-F165_W0QQitemZ120465699213QQcmdZViewItemQQptZCamera_Flash_Accessories?hash=item1c0c50b18d#ht_2874wt_1161

What do you think of those and how do you best use 'em?


Mark

Russ MacDonald said...

Hi Marc,

The reason for using Rear Sync is that IF you get any ghosting, it will be on the proper side of the motion.

However, as I pointed out, if you use Rear Sync, then you must use Camera Manual mode, because if you use Aperture priority, the camera will also select Slow Sync, and that causes the shutter to go way too slow.

That's why you have to use camera Manual if you use Rear Sync.

The settings on the camera are not critical when shooting flash in dim ambient using camera Manual mode. Just set f/2.8 to f/4.0, ISO 400, and 1/80th to 1/120th and shoot. The flash metering will automatically expose the subject properly.

Hope that helps,

Russ

Russ MacDonald said...

Mark,

I don't use a a Ring Flash in my work, so I really can't comment on that.

Russ

Russ MacDonald said...

Mark,

If you want to get more technical about setting the camera controls when shooting flash, just set them to underexpose the ambient by to 2 to 3 stops.

You can do this by turning OFF the flash, and using the built-in meter in the camera. Just adjust the controls to make the meter read 2 or 3 'big' marks on the dark side of zero.

After you get the camera controls set for 2 to 3 stops dark, turn the flash back on and shoot.

Russ

Anonymous said...

Russ,

Thank you so much for your very helpful explanation. I've always struggled with using flash in Aperture-priority mode - hopefully my problems are solved!

On a side note, what don't you like about ring flashes? The way I was planning to use it when I am shooting my children (there isn't always a white wall I could bounce the light off)

Thanks again,
Mark

Russ MacDonald said...

Hi again Mark,

It's not that I don't like a ring flash. In fact, I have used them for macro work.

It's just that I don't need one for my wedding/portrait business.

When I use the flash on the camera, I use a Gary Fong Light Sphere II. It works great in all situations, including whenever I need to shoot up close and there is no bounce.

Russ

mg said...

I see, thanks

Joseph said...

Hi Russ,
Great post and a very informative blog. I will check to see if my D90 goes into slow sync when shooting aperture priority. If it does, then you're suggestion to use manual is a very good one. Instead of camera manual, is there any disadvantage to using shutter priority set to 1/125 or 1/200? Joe B.

Russ MacDonald said...

Hi Joseph,

In Aperture priority mode, the camera will go into Slow Sync if you select Rear Sync (or Slow Sync).

If you select regular Sync, the shutter will not drop down to low shutter speeds. It will stay at the Flash Shutter Speed that you have chosen in the menu (default 1/60th).

The problem is that 1/60th is often too slow for many situations. That's why you should be in camera Manual mode - so you can increase the shutter to 1/80th or higher.

Russ

Joseph said...

Thanks, Russ. I tried it today and you were right: the ghosting was going in the wrong direction. So I just reset the low-end shutter speed to 1/60.

CGO said...

Russ, good demonstration and explanation. I assisted at a wedding reception and got some very nice "action" shots on the dance floor using rear sync with aperture priority mode. Using my Nikon D300 with a variable-aperture zoom and with the ambient light varying depending on where I stood and what direction I faced, I don't think manual exposure would have been practical. Wouldn't aperture priority mode combined with -2 ambient exposure compensation and +2 flash exposure compensation accomplish very nearly the same thing as your recommended manual exposure? It's true that my shutter speed would vary, but my subject would be properly exposed and the background would be 2 stops underexposed regardless of my zoom setting and regardless of which direction I'm facing.

Russ MacDonald said...

Hi CGO,

In Aperture priority mode and rear sync, the aperture would be fixed at whatever you set, and the shutter speed would go very slow. In fact, it could go as slow as several seconds in very dim light.

This would cause massive ghosting and I don't think the images would be very good.

I use camera Manual in this situation so I can control how long the shutter stays open. I never want any slower than about 1/8th sec on the shutter.

The actual ambient exposure that you use (the ev setting and all) is not important. The flash will provide most of the exposure. You just want enough ambient to give a hint of ghosting to convey motion. You would never want several seconds on the shutter when shooting dancing.

Take a look at the exif data in your good dance pictures. I'll bet the shutter was no slower than 1/8th sec. Then take a look at some bad ones. You'll probably find the shutter was much longer; maybe several seconds, depending on how dark it was. You have to prevent those long shutters to get usable images. Otherwise there is way too much ghosting.

Hope that makes sense,

Russ

Redwine said...

Hi Russ,

Another great chapter just when i thought i have everything covered.

Regarding the Flash Shutter Speed,
isnt it great if Nikon provide the option to allow user to change the setting up to the Max Syn Speed ?

I'm learning to shoot portrait, and i have to shoot on Manual to reduce the number of motion blur picture as i prefer a shutter speed of 1/100 or faster on my 50-150 zoom lens.
I'm thinking whatever number you put there will depend on the lens you use to reduce handshake problem.

In addition, you mention to meter 2-3 stop below ambient,
For outdoor portrait or indoor portrait in big hall where the flash have no effect on the background, does the 2-3 stop still apply ?

Thanks

Russ MacDonald said...

Hi Redwine,

It would be great if Nikon would allow you to set a higher Flash Shutter Speed than 1/60th. In fact, that is the main reason you have to use camera Manual mode when shooting indoor flash!

Outdoors, you want the background to be close to the the proper metered exposure. Most of the time in bright light, there is no way to make the background 2 stops dark anyway, because the flash doesn't have enough power. Besides, it would look weird.

That's why, outdoors, you should use TTL-BL with one of the auto modes. It will balance the flash power with the background to make the subject brightness equal to the background brightness. Watch out for camera A mode! The max shutter speed you will have is the Flash Sync Speed, and that is way too slow for daylight. I usually switch to P mode when using TTL-BL outdoors in bright daylight.

Or, I use Auto FP Sync mode and camera A mode. That will allow flash photography at all shutter speeds. This is wonderful for shooting portraits outdoors in bright light, so that you can add fill flash, and still blur the background with a wide aperture. The downside is that you have to be very close to your subject (within 10 feet or so) because the max flash power in FP Sync mode is less than half of regular sync.

I have written several other blogs that cover these things. I invite you to check them all out.

Russ

Redwine said...

Hi Russ,

Thanks for the invite.
Been reading them again and again.
Thoroughly enjoy them.

Cheer !!

Juvenal said...

New Post! Thanks. Your site is extremely helpful

Russ MacDonald said...

Hi Juvenal,

Thanks for the nice feedback!

Russ

Mark said...

Hey Russ,

Thanks for the great information. Im new to flash photography and your site has helped me considerably in understanding the Nikon CLS and flash photography in general. I have purchased several books on lighting and flash photography but none of them has explained it the way you did. Easy to read, laymen's terms. But what I love most about your site is how you actually explain when and why someone should use the various settings on the SB800. Love it. I only wish I found this site earlier and I could have saved all that money I spent on those books. Have you ever thought of putting this info in easy to use spread sheet or quick reference guide that someone carry with them to a shoot.

Thanks again,
Mark

Russ MacDonald said...

Hi Mark,

Thanks for the nice feedback!

I have focused my blogs more on explaining things so you don't need a 'cheat sheet'. My goal is to present enough information to allow you to be able to reason out how to set your camera. That's how all pros do it, and I've always thought that there is no reason the average non-pro photographer cannot learn to do it the same way.

What do you think?

Russ

Chris said...

Hi Russ,

I was shooting a night soccer game and was using flash for the post game 'jube' shots. Had some of the ghosting you refer to (was shooting AP f5.6)

What do you think, OK to apply the same concepts here, for outdoors night shots like this? Should I have shot Manual, etc?

Russ MacDonald said...

Hi Chris,

Absolutely!

Any time you are in low ambient conditions (indoors in low artificial light, outdoors at night, etc) always switch to Camera Manual mode and increase your shutter to 1/80th or higher to control the ghosting.

In fact, I am working on a new blog that addresses exactly your question. It will tell you step by step how to set your camera and flash for any ambient condition.

Russ

Anonymous said...

Russ,

When shooting flash in Manual mode (camera), is there any reason why I shouldn't just leave my flash always in Rear sync?

Thanks for your great site. I'm learning my way around my new SB-900 (with D90) and your posts getting me out of Aperture Priority in to Manual in indoor lowlight ambient have made all the difference. Thanks for also pointing out the difference between Rear Sync in Manual and Aperture priority; now I know why I could never get a proper shot when experimenting with Rear Sync in Aperture Priority.

Quash

Russ MacDonald said...

To Quash,

Thanks for the compliments!

But be aware that everything I write is about the SB-800 or
SB-600, since I don't own an SB-900. I'm not sure about several new modes on the SB900 and new features it has.

As a practical matter, it is perfectly OK to leave Rear Sync turned on all the time when using camera Manual mode.

However, when in Rear Sync the flash has slightly less maximum power, because more of the tail is wasted.

Also, if you leave the camera in Rear Sync mode mode and forget it and switch to camera A mode or P mode, it can set your shutter as slow as 30 sec in an attempt to expose the background.

I usually leave mine in front sync, because I never seem to remember it when switching to camera A mode. That mistake can destroy a lot of images before you catch it.

Russ

geomcs said...

Hi Russ, I happended upon your site and noticed that you are in Richmond Hill. I live in Savannah. Great info! I will be reading more. Thanks,
Mike Schmidt
www.moonriverphoto.com

Russ MacDonald said...

Hi Mike,

Always glad to meet another Savannahite.

Maybe we'll run into each other sometime.

Russ

Mark said...

Hey Russ,

I agree regarding with your comment that it's best to have the knowledge about how and why your flash works the way it does, so that we can set our cameras correctly.
With that in mind I have a question regarding Bounce Flash. Q: Since the flash is pointing in a direction other then towards the subject and the metering system for the flash and camera are, is there any particular mode that the flash and/or camera should be set in when using bounce flash? And what considerations should make when it comes to distance both with the subject and the where the flash points?

Thanks,
Mark

Russ MacDonald said...

Hi Mark,

The brilliance of the iTTL and iTTL-BL systems is that they both compensate automatically when the camera and flash are pointed in different directions!

The way the system works is that the flash fires a monitor preflash and the camera measures the reflected energy from that preflash that bounces off the center portion of the frame (the subject). So, if the flash is pointed at the ceiling, the amount of reflected preflash energy will be much lower than if the flash were aimed directly at the subject. The camera sees this and increases the flash power to make the reflected energy standard.

Therefore it doesn't matter where you point the flash. The system will set the power to get the correct reflected energy off the subject.

Now, with the iTTL-BL system, focal distance from the lens is also used for setting the power. This means the distance from the flash to the subject must be the same as the distance from the camera to the subject. The system still uses the preflashes to determine how much power the flash has to be boosted above normal. This is one reason why iTTL-BL is not available when the flashes are in Remote mode. This also explains why iTTL-BL works best with the flash in the hot shoe and not on a flash cable like the SC-29.

It also doesn't matter whether you add diffusers or umbrellas to the flash . A diffuser or umbrella weakens the reflected preflash energy, so the system automatically increases the flash power to compensate.

Russ

Chris said...

Russ, this nugget caught my eye:
"This also explains why iTTL-BL works best with the flash in the hot shoe and not on a flash cable like the SC-29."

I wasn't aware of this. I thought that turning the dial so that the little 'feet' contacted the flash would allow me to use the infrared receiver in the SB-29, duplicating the functionality of when the flash was in the camera body shoe.

Can you elaborate?

thanks,

Chris

Russ MacDonald said...

Hi Chris,

When you mount the flash in the SC-29, it thinks it is mounted in the hot shoe, and all functions are executed with that assumption.

With TTL, all is fine, because the placement of the flash is not one of the considerations.

With iTTL-BL, the equations that are run to calculate the power use the distance that the lens reports as one of the major factors in flash power. But for this to work right, the flash must be at the same distance from the subject as the camera. If it is closer, the flash will fire hot and if it is farther away it will underexpose.

So, iTTL will work just fine if you put the flash on a bracket that holds it the same distance from the subject as the lens, but if your assistant holds the flash off to the side and behind you, it will underexpose.

Hope that helps,

Russ

Chris said...

ahhh, perfect, thanks. I do have my flash in a bracket above the camera, so it's the same distance from the subject...think I'll be good. Understand now, thanks for clarifying.

Chris

Will said...

*Great info*. Has really helped me understand the love for manual mode in indoor settings. Thanks so much.

Russ MacDonald said...

Hi Will,

You're welcome! I'm glad you find the info useful!

Russ

Ardy said...

Russ
I join with others in amazement and appreciation for the information that you have posted here.

I am a little curious on the following. Is there any way to incorporate a slave flash into what you are suggesting?

For example, suppose your slave flash ignores the pre-flashes and only flashes with the correct flash. And suppose you are doing portrait work and only use the slave to provide a wash of light for the background.

Thx in advance
Ardy

Russ MacDonald said...

Hi Ardy,

Well, there is an easy way incorporate a second flash as a CLS Remote. In that case it has to be a Nikon CLS flash. You can't use a low cost simple flash for this. A Nikon SB600 is the most inexpensive flash you can do this with.

If you do that, then both the on-camera flash and the Remote will work together in iTTL mode and automatically calculate the correct exposure.

Or, if you want the background light to just make a "wash of flash", then you put the Remote in Commander Manual Mode (from the Commander menu on the camera or Commander Flash)), and you can set its power level from the Commander on the camera. I do this for my hair light. I can then dial it up or down in power without ever coming out from behind the camera! Very nice!!

However, if you want to use a traditional optical Slave that is not CLS compatible, then you have to turn CLS (iTTL) completely off and put all flashes on full Manual mode. Then, you have to make sure your slave flash has an opitcal trigger to fire it when the Master flash fires.

This is because the CLS mode always makes a preflash that will fire any simple slaves early. I have not found any simple slave that will reliably ignore the preflashes, but there may be one out there I don't know about.

Nothing is automatic when you do this. You have to set your flashes manually at the flash heads and measure their strength with a meter to get your f/ stop, just like with a monolight strobe.

Hope that helps,

Russ

filipe m. said...

Oops,

I guess this answers my comment on the other post...

Thanks!

Russ MacDonald said...

Hi Filipe,

No problem.

Russ

Raymond said...

Hi Russ,

Another wonderful piece of article (btw, it's fun how your facial expression looked the same in those shots!! :P)

After reading it (and most of the comments that follow) I do have some questions in mind:
Q1. Why do u recommend to underexpose the ambients by 2 or 3 stops?
Q2. The other night I was shooting snapshots of friends in a wedding banquet (indoor function room with dim lighting). I shot in manual mode with f4.5, 1/60, SB-800 on hot-shoe (bounce) with my D70s. I noticed that the subject (in center) was correctly exposed but the background seemed a bit darker than my liking... what settings would you recommend if I'd prefer a slighter brighter background in those shots? Please excuse me if the question sounds dumb, I'm still learning flash photography!! :)

Thanks a lot!!

Russ MacDonald said...

Hi again Raymond,

Q1 A: I recommend that you underexpose the ambient by 2 or 3 stops so that it will make your flash photography easier. If you allow the ambient to contribute significantly to the subject, it will add to the regular TTL flash exposure and you can easily get overexposure. Then, you have to adjust the flash EC to reduce the flash power manually. If you underexpose the ambient by 2 to 3 stops, it will not contribute significantly to the subject exposure and the regular TTL flash power will be more likely to be correct. Of course, when you underexpose the ambient by 2 to 3 stops, the background becomes darker.

Q2 A: Yes, that is normal. The goal in party photography is to expose the subject correctly and expose the background darker but still easily visible. You can increase the brightness of the background by slowing the shutter, but 1/60th is already pretty slow. 1/30th would allow lots of ghosting and possibly overexposure of the subjects. You didn't mention the ISO you were using, but, for example, increasing from ISO 400 to ISO 800 will also brighten the background by one stop. Of course, that may also add some noise, especially with older cameras.

Another thing I didn't mention about brightening the background is that usually the ambient light is a different color than the flash. So, as you slow the shutter, the ambient begins to add to the exposure of the subject, and in addition to overexposure, you start to get unnatural color shifts that cannot be corrected.

In any case, the slower you make the shutter, the more difficult it becomes to make good flash pictures, and some of the time it becomes impossible (like the mixed lighting situation).

For all these reasons, that's why I recommend keeping the shutter high enough to underexpose the ambient contribution on the subject by 2 to 3 stops.

Hope that helps.

Russ

JEB said...

fantastic just what i needed.

Tom said...

Thanks a lot for this post.
I have just another question:

To make the position 2 to 3 steps darker (in M mode).
Should I make a shoerter Shutter or a closer aperture?

I ask because of this.
With the shutter I would really freeze the blur.
and with the aperture I would increase the sharpness of the background.

but when using flash in i-ttl (and I think I should)
to close the aperture would darken the background but the flash would make the subject brighter.
so what should I do?

In M mode make the relation of shparpnes between background and subjekct (with the aperture) make the shutter that short that there is no blur and let the flash do the rest?

But which effect does the aperture and the shutter have else?

it is different to manual flash light. (there the aperture regulates the relation of bachground and subject and the shutter just the lever of the background. is this right?

Thanks a lot

Russ MacDonald said...

Hi Tom,

Your comment is correct.

The iTTL system regulates the power of the flash to keep the brightness of the subject constant.

This means that as you change aperture, the flash power will change power to keep the subject at the same brightness.

On the other hand, the shutter never affects flash power (when using normal flash sync), because the duration of the longest flash pulse is only 1/1000th sec (1.0 millisecond). In regular flash sync, the highest shutter speed that can be selected is the flash sync speed. This is is (1/250th (4 ms)or 1/200th (5 ms), depending on which camera you use. So, you can see that the shutter is always open for the entire flash pulse no matter what shutter speed you select. Obviously, if the whole flash pulse is always captured, the shutter speed can have no effect on the flash power or the flash contribution to the image.

The thing that is confusing is that both shutter and aperture affect the ambient contribution to the image. So, to darken the image by 2 to 3 stops as I have suggested, either the aperture or the shutter can be used to accomplish that. The reason I recommend using only the shutter is that if you darken the background with the aperture, the flash has to fire at a higher power to maintain constant brightness on the subject, and when this happens, it counteracts some of the background darkening as the flash also brightens the background a small amount. Also, if the flash increases too far in value, it will become maximum, and then further closing down of the aperture will begin to darken the subject as well as the background, because the flash can no longer increase in power to compensate.

So, the best approach is to darken the background with the shutter only, to avoid all these problems.

Hope that helps,

Russ

Tom said...

Thank you.
So make the shutter shorter till the 1/250. And then the aperture.
Or I have to use FP. (Which has the effect that the flash will probably not be strong enough to be the main light. right?

Russ MacDonald said...

Hi again Tom,

Yes, you are exactly right.

This is why I recommend to use P mode when shooting fill in bright light. It will do exactly what you just wrote. First it runs up the shutter until it gets to 1/250th, and then it closes down the aperture to control the exposure after that.

Or for outdoor portraits you can switch to FP mode and use camera A mode with a wide aperture to blur the background. Then, the shutter will run up to whatever necessary to control the exposure, but the subject has to be pretty close (under 15 feet) to get any significant fill due to the reduced maximum flash power maximum flash power.

Tom said...

thank you!
But it does not make sense to deactivate de FP.
Or is there a situation you could have problems when activated?

Russ MacDonald said...

Hi Tom,

Again, you are right!

As long as a photographer understands fully what he is doing, it's perfectly OK to leave Auto FP High Speed Sync selected, since the camera only uses FP when the shutter goes above flash sync speed.

However, for new photographers who are not 100% sure of what FP is and how it gets activated, I recommend keeping the camera in normal flash sync, because it prevents long strings of bad images if mistakes are made.

Russ

George said...

Very interesting thank you for your Articels.
I Have a question too.
I am owner of a D300(s) and there are 2 FP Times 1/250 and 1/320.

Is there a reason to use the 1/250?
Because with 1/320 I would have the full poer of the Flash in the shortest possible time (before FP starts to work and reduce the flash power)
But in a Book and browsing the web i read using 1/320 reduced the Flashpower too.
How could this be?

Thanks you for answering my question.

Boris said...

Hi Russ,

Thanks for a fantastic blog. I just bought a SB-600 for my D200 and ramping up on flash photography.

I have two questions:

1) In this post, you specifically recommend using higher shutter speed to shoot people at low ambient light, yet on a different page you advise (and show wonderful results) in using low shutter speed to balance background and subject. There, you claim that it's OK to use low shutter speed, as it's the fast flash that "freezes" the subject. Can you comment on the difference?

2) What metering do you recommend for indoor flash photography (eg: party)? I'd have thought Matrix, but my impression is that you're using Center-weighted. Why?

Many thanks!!

Russ MacDonald said...

Hi Boris,

There is no right or wrong when it comes to flash. The problem is fully understanding what is going on to be able to get a proper exposure.

When you use a higher shutter speed, it reduces the ambient contribution to the image, and that makes it easier to hit the right exposure.

It is perfectly OK to use a slow shutter speed to allow more background to show. However, as soon as you do that, you have to start using negative flash compensation, because the flash adds to the ambient, and if you have lots of ambient and you don't turn down the flash, you will get overexposure.

So, the reason I talk here about keeping the shutter speed high is to keep the ambient light low enough that you don't have to use negative flash compensation.

Also, as soon as you allow lots of ambient into your exposure, you have to worry about other things like ghosting when there is motion, and white balance problems when the flash doesn't match the ambient.

So, the high shutter is just to make things easier to get a proper exposure.

Russ

Russ MacDonald said...

Hi again Boris,

I forgot to answer your question on metering.

If you read all my blogs, you'll find out that the camera meter has absolutely no effect on the TTL flash. All the meter does is measure the ambient light, so if you keep the ambient down low, by using a fast enough shutter, the camera meter doesn't do anything. You can use spot or matrix or center weighted and you will get exactly the same results - just as long as the ambient is not significantly contributing, which it shouldn't ON THE SUBJECT.

Your comment about center weighted has me wondering if you really understand that the flash has its own metering system, completely separate from the camera, and that system is center weighted.

This is why you can shoot a flash picture in complete darkness, and it will be exposed perfectly. The flash exposure metering controls it.

Now, be careful to read my blogs carefully. When you use TTL-BL mode, then the camera metering DOES AFFECT THE FLASH POWER. Then, it does make a difference which metering mode you use on the camera. For all of this blog, I have been ONLY TALKING ABOUT REGULAR iTTL. Then, the camera meter has no effect on the flash power.

Russ

Boris said...

Russ,

Thanks for clarifying things and for putting together such a helpful collection of articles. All the best,

Boris

eggstatic! said...

Hi Russ!

having always loved shooting in analogue, I'm now trying to get my head around digital!

Im currently shooting on a D70 with an SB-600. I want to use my flash off camera and have done this sucessfully before using two hotshoe adaptors and a cable but for some reason today this did not work! I was shooting outdoors on manual mode and was using the flash on a stand with an umbrella to create some fill in flash for my subject. The flash works as when I test fire it works. I believe I might have touched a setting on my camera and cannot figure out what (or maybe the adaptors are faulty - however have only had them for a couple of weeks).

Any suggestions would be greatly appreciated!

Cheers Russ... and well done on a great blog!

Emma

Russ MacDonald said...

Hi Emma,

Thanks for the nice feedback!

It's hard to say what might have been wrong, but it is very common for PC Sync cables to not make good contact. I always carry a small pair of pliers in my bag to squeeze the shell of the PC connectors so they fit more tightly.

Russ

ENID said...

The settings on the camera are not critical when shooting flash in dim ambient using camera Manual mode. Just set f/2.8 to f/4.0, ISO 400, and 1/80th to 1/120th and shoot. The flash metering will automatically expose the subject properly.

Does this apply to the D70s as well as the D200?

Russ MacDonald said...

Hi Enid,

Yes! Everything applies equally to the D70 and the D200 and all newer CLS cameras.

One thing to be aware of, however, is that there are improvements to each generation of new cameras. Especially the TTL and TTL-BL algorithms are better in today's cameras than in the D70. The newer cameras are more forgiving of errors with the flash. For instance, if you use TTL-BL on a D300 indoors, it has new programming to recognize that it is being misused, so it copmpensates and goes into a pseudo-TTL mode to try to fix your error. Sometimes it works great - other times not so well.

So, in the D70 generation, you have to pay strict attention to what I wrote to get excellent flash images.

Hope that helps,

Russ

Александр Козиев said...

Russ,
I don't know how to count all the times I said "thank you" as I read your articals!
I have a quastion. I used to always use my d90 in a commander mode to control sb800/600 as a remote. I tried to use sb800 as a master but I turnd off sb600, leaving sb800 in ttl/master and noticed that it underexposes compared to the regular(not master)TTL mode.

Russ MacDonald said...

Hi there (I can't read your name in Russian alphabet),

Whenever you use wireless CLS, the system assumes you will be using more than one flash, and where the flashes overlap they will add. Consequently, each flash will underexpose slightly.

So, when you use the SB-800 in Commander mode with only the Master turned on, it will always underexpose slightly to give a proper exposure when you have additional Remote flashes.

Hope that helps,

Russ

Alexander said...
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Alexander said...
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Alexander said...

Yes, my name is Alexander, thank you very much. At least, there is nothing wrong with the settings or the flash. However it is kind of strange, ispecially after using built-in flash as a commander, where it doesn't do that even if you turn on remote flashes in the camera commander settings... well, if it's the way things are.. I wonder, if it can be fixed by power compensation in the master flash wich will work for every shot, or it's something that has to be set manually every time?

Alexander said...

Sorry about the mess. It appeared that my post wouldn't get through, so I kept posting the same one. Hope you can remove it, including this one.
:-)

Olu said...

wow..this is good information, thank you, better than the books I have bought. You should write a book on this :)
Just a quick question, when you use Gary Fong LightSphere, do you use it with the inverted dome?
Many thanks.

Russ MacDonald said...

Hi Olu,

Thanks for the nice feedback! But writing a book a way too much like work!

Sometimes I use the inverted dome with the Gary Fong Light Sphere, and sometimes I do not. You have to understand the purpose of the dome to understand when to use it.

The inverted dome reduces the amount of light going up, so it reduces the bounce off the ceiling. This also increases the light that goes forward as well as out the sides, which increases the direct light on the subject as well as the bounce off the walls.

So, in a small room with light neutral colored walls and ceiling, you will get the softest and best distribution of light with the dome installed.

In a room with a very high ceiling that is still within reach of the flash, removing the dome will often allow a ceiling bounce which almost always improves the image.

Outdoors, the dome should remain installed, since there is nothing above you from which to bounce.

For fill flash on a bright day, point the LS with the dome installed directly at the subject and use TTL-BL flash mode for great results.

Hope that helps,

Russ

Olu said...

Thank you Russ for the prompt response, it sure helps. I often shoot in my local church events which has dark high ceiling, so I guess using the inverted dome makes sense here. Would it make any difference if I use the dome in a 'concave' or 'convex' way/position? Would it also make any difference for outdoor use using it either way?

Blakar said...

Russ,

I just had a great idea to simplify things then realising it's probably not possible :)

I figured that if I dialed in -3EV on the camera that I could walk around in varying low light conditions on a party and shoot flash creating an automatic 3 stop difference between flash and ambient. I then realised it wouldn't work because I probably need to go into matrix metering to get the correct reading while I'd need the flash to be in TTL, not TTL-BL. And that's not possible for my D7000/SB700 combination.

On the other hand I'd suspect that in general the subject (not wearing black for ease of thought) is as lit as the environment. So if I just do not put it into matrix metering I'd get about what I'd want.

Do you think this will work (I'll try it for sure) or am I just trying to make things too easy? :)

Russ MacDonald said...

Hi Blakar,

The only time the metering mode on the camera affects the power of the flash is when using TTL-BL.

In regular TTL mode, you can select any camera metering mode you want to, and it has no effect on flash power.

Also, dialing in -3ev has no effect on the camera exposure when the camera is in Manual mode. It will affect the meter display, but normally you do not use the meter for regular TTL flash.

Blakar said...

I did some quick tests. While I need to do some more testing I do think I can get it to work.

What I wanted to achieve:
You have indicated in the cookbook that we need 3 stops to make the flash primary over ambient. So what I wanted to know was whether I could get the camera to do this for me for example while being in Aperture Priority. This because light may vary if you move around and you may not always want to start working out things yourself.

What I planned to do was to tell the camera to underexpose by 3 stops. This didn't exactly do what I wanted cause I didn't think off the fact that -3EV in the camera also means it tells the flash to underexpose as much. Though this was fixed quite easily by dialing in +3EV on the flash.

So what I did:
- Put camera in spot-metering (see also below)
- Aperture priority mode on camera
- -3EV on camera
- +3EV on flash
- shoot in conditions where ambient would not be overpowered at 1/60th shutter with ISO fixed so that only shutter can be adjusted

What happens:
The camera adjusts the shutter to get its desired -3EV exposure and the flash still fires to get a normal exposure (as the +3EV cancels out the cameras -3EV).

Some notes on the D7000/SB700 combination:
- The SB700 switches to TTL-BL when the camera is in matrix metering
- The SB700 switches to TTL-BL when the camera is in center weighted (though I must check if this varies depending on the center weighted size which is adjustable)

Russ MacDonald said...

Hi Blakar,

What you say might work, but I wouldn't do it that way, because if you take a series of pictures, the background brightness will be varying, and that isn't normally acceptable. You want the background to stay at one brightness, and let the flash adjust its power to keep the subject always at the same brightness. Using camera Manual mode at one shutter speed and aperture keeps the background at the same brightness.

Also, it's not quite correct to say that the flash switches to TTL-BL when matrix metering is selected. That only occurs if the flash is set to TTL-BL to start with. If you set the flash to regular TTL while in Matrix metering, you can switch the metering to whatever you want and the flash will stay in regular TTL.

The only time TTL-BL can work is when a large portion of the frame is metered by the camera. That can only occur in Matrix or CW metering, and this measurement is used as a proxy for the ambient brightness that TTL-BL needs to balance with. In Spot metering, the only thing that is metered is the subject, so TTL-BL can't work, because there is no metered value of the ambient light to balance with.

Also, in camera A mode, the shutter is limited to a default minimum of 1/60th sec (Flash Shutter Speed). Therefore, the camera may not always be -3ev. It could often be much more.

Russ

Blakar said...

Russ,

I actually tried it out extensively and I do think it works (for me).

My main goals:
- Minimise pitch black backgrounds
- Overpower the ambient light
- No need to change settings while walking from area to area and room to room

I do understand your concerns but I think there's quite a bit of mitigation already in my scenario.

Changing backgrounds: True, if you have multiple photographs of multiple subjects on the same background or even the same subject with a different focus point it may come out a little different. Though in general I'm on the move so picture to picture background comparison is not that important. Even in M-mode I'd face this issue as ambient light changes from area to area and room to room so keeping it at the same level would require a lot of work altering settings in M-mode.

Default flash shutter at 1/60th:
Indeed you're right here but this is easily fixed. As the settings assure you'll have a 3 stop difference between camera and flash you don't need to be afraid of changing this. While shooting more tests I had mine at 1/15th and I altered sync flash speed to 1/250 (to improve my top end a little bit). As a result my range in which I can assure I'll overpower ambient is from 1/15 to about 1/240 so 4 stops. And the camera will help me reach the goals set out above without me doing any changes. In M-mode change from one room to the other with a change of 3 stops in ambient light would certainly require me to alter settings.

For the TTL-BL part: as I had actually already read in one of the comments here the SB-700 picks the mode itself. The manual confirms this:
"Either the i-TTL balanced fill-flash mode or the standard i-TTL mode option is available depending on the camera settings. The SB-700
does not have i-TTL mode type selection."

Obviously as an amateur I'm taking the pragmatic approach. And I try to think outside the box in order to get great pictures with at least effort as possible. Off course I didn't invent the magic bullet and not all shots came out great. But thanks to the guideliness in your posts I did go from buying an SB700 to shooting with a special workflow in only 5 days. And the pictures are quite a bit better than what I could get out of my old D100/SB28DX combo (but that wasn't really known as easy to work with)

Russ MacDonald said...

Hi Blakar,

First, none of the Nikon cameras have a setting for TTL-BL or TTL (for an external flash). That setting is always on the external Flash.

If a book says that the camera picks TTL or TTL-BL automatically, the book is wrong. I already explained it, but I will explain it again.

If you have the flash in regular TTL mode, then the metering on the camera has no effect on flash power. If you have the flash in TTL-BL mode, it will switch to regular TTL mode if you select spot metering. This is because TTL-BL requires a background ambient measurement and spot doesn't give you that.

If your method works for you that is great!

filipe m. said...

Russ,

I'm not sure if you're aware that the SB-700 doesn't have a TTL / TTL-BL mode selector like the previous 600 and 800 before it. I'm assuming the book Blakar is talking about is saying that the change based on camera settings is exactly the change you've described (TTL for Spot Metering, TTL-BL for CW and Matrix), precisely because it's now the only way of selecting between the two modes on the SB-700.
Just a different way of looking at the same thing, I guess, but potentially misleading for anyone who uses both the old SB-600 / 800 and the new SB-700. I can't comment on the 900/910 as I've never used one.

Blakar:

I'd say that if you're using Spot Metering to force the flash into TTL mode, the only reasons why your backgrounds are coming up as you want them is because your subjects are pretty damn similar in tone and near middle grey...

I'd hazard a guess that if you were to shoot a very light or white subject everything would come out underexposed, and conversely shooting something dark would yeld an overexposed photo (and this might be one of the bits that's causing you to say not every photo comes out perfect). Essentially what you are doing with your method is forcing the camera to spot meter on your subject, turning it into 18% grey and go from there exposure wise. It might not even be metering the background at all, so you're literally metering for the light that's falling on your subject, and hoping this reflects the current lighting conditions.

I can see why this method could work indoors, under pretty constant ambient light inside each given room. With various degrees of exposure compensation / flash exposure compensation according to subject tone it can work, but outdoors it's a potential nightmare...

As Russ said, if it works for your shooting style, then that's great, but like every other "workflow", the more aware of its shortcomings you are, the better you'll be able to deal with them and avoid the "not so perfect" pictures. If you're using TTL / TTL-BL and semi-auto exposure modes, you really have to think like the camera.

Hope this helps a bit!

Blakar said...

Russ,

the book is the SB-700 manual, free for download and created by Nikon ;-) Furthermore seeing is believing, the flash happily displays TTL or TTL-BL depending on how you alter the camera's metering. Some would call it progress though I must admit there are most certainly issues with it, when it switches to TTL-BL it's good to read your docs here cause at least then one understand why the pictures are sometimes not what was needed.

I've the impression that flash and camera communicate quite a bit today cause the camera knows damn well what I'm doing. If I dial in -3EV on camera and +3EV on flash then this ends up as being -3EV camera and 0EV flash in the exif. So even for backreference I can see what I did.



Felipe,

I did indeed intend to use this in common ambient light which generally spreads pretty equally. Obviously any situation that calls for TTL-BL isn't what I'd be looking for when using this. Nor are other situation where some of the background lights are very pronounced. Off course for the picture to be blown it requires the spot meter to measure something that is over 3 stops less than the background, otherwise the background won't blow out. Note that the primary reason that I used this rule was because Russ showed how it affected ghosting. I want to photograph people in natural positions, not posed. As such I do not control movement and wanted to assure that the metering assures the 3 stops difference for the subject in order to avoid ghosting.
I also think you're underestimating the RGB meters capabilities a bit when going for the 18% gray assumption.

As to what works and doesn't: it only works well if I bounce the flash and do not attempt to bounce too much of the light directly to the subject. Pulling out the reflector immediately gives an undesirable effect. Maybe it's just because I don't like the way it looks but it sure is as if avoiding direct light from the flash works better. Because I did not have to fiddle with the settings I mostly spend my time triangulating the best angle for the SB700 head ;-)

It's not spectacular what I did but I'm pretty happy. I bought the SB700 on saturday knowing I'd be using it at a party on thursday. The whole workflow was tested in non-similar conditions and for 5 shots only due to limited time. So if the pictures turn out to be pretty good after that that surely is a win :)

Russ MacDonald said...

filipe and Blakar,

My mistake! You are absolutely correct. I assumed the SB-700 was like its predecessors, which was wrong. Thank you for pointing that out. That will teach me to assume anything! I do have the manual - just didn't notice that little fact.

That makes the SB-700 like the SB-400, which also does not have a TTL/TTL-BL mode switch.

I will delete this and the other incorrect comments in a day or so to avoid confusion for future readers of these Q&A.

I will address more comments to this topic in a separate post.

Russ

Russ MacDonald said...

Hi Blakar,

The communication between the camera and the SB-700 is exactly the same with the SB-800. In fact, you can make the SB-800 simulate the way the SB-700 works by putting it in TTL-BL mode and then using the settings on the camera to change its mode.

When the flash is in regular TTL mode, there is no metering information exchanged between the camera and the flash at all.

That's why it's best to use camera Manual mode when using regular TTL. You set the camera to expose the background the way you want it (usually two to three stops underexposed), and then the flash sets itself to expose the subject correctly.

Of course, you still have the issue with the flash underexposing when there is a lot of white in the frame, and overexposing when there is a lot of black.

One way to control this is to zoom in on the subject's face, and press FV-Lock. Then zoom back out and take the shot. With the subject's face filling the frame, ususally the flash metering is accurate.

There is more communication between the camera and the flash when in TTL-BL mode, because the camera uses either matrix or CW metering to measure the brightness of the ambient and sends this info to the flash. The flash then sets its power to match the brightness of the ambient. Thus you get 'fill' flash.

However, there is one caviat when in the TTL-BL mode: proper fill flash will only be generated when the camera meter is zeroed. If you use the camera in one of the auto modes, the meter will be zeroed automatically. If you use the camera in manual mode, you have to make sure the meter is zeroed by hand. In bright ambient (like daylight) camera P mode is usually the best mode for shooting fill flash, so you won't run into the maximum shutter speed called 'flash sync speed' and end up with severe overexposure.

So, if you are indoors, you should always select spot metering to force the flash into regular TTL mode. Then, if you want to select camera A mode and -3ev it should work OK as long as you don't care about varying background brightness from shot to shot.

Don't use Matrix or CW metering or the flash will go into TTL-BL mode, and your subjects will usually come out too dark.

Dave Bennett said...

Hi Russ,

Your series has been very helpful to me as I use my SB's, both on- and off-camera.

In a couple of weeks I will be shooting a horse show in a covered arena. It will be too dark to get the shutter speed up and capture the action of the moving horses without using flash. Trying to use TTL-BL to get fill flash would not work very well at all. I have been thinking through this and would like to get your thoughts...

I have an SB-910, an SB-600, and light stands, along with Pocket Wizards to communicate between the camera and the strobes. Camera will probably be my D700.

Most show photographers shoot from near the center of the arena to capture images of horses moving along a relatively short section of the ringside to get "standard" horse show shots. I plan to do the same. I should be able to use M- camera mode, TTL-flash and then just FV-lock. Or I could just use manual flash and leave it at one setting because the flash exposure should stay essentially the same.

There is an island in the center where the announcers, organ, and show facilities stay. I could put a lightstand on each long side of the oval and just outside of the island with the flash pointed at the section of the rail toward which I would be shooting. That would get the flash source higher and not quite as close to the moving horses. So, it would not be as intrusive as an on-camera flash.

The alternative to this would be to use one of the SB's on a camera bracket. The photographers that I have observed seem to do it this way. But they have been using the same method for years without trying remotely-triggered flash.

Does this sound reasonable? Suggestions?

Thanks!
Dave

Russ MacDonald said...

Hi Dave,

One reason many pros use a light bar, and keep the flashes on-camera, is to minimize flash shadows.

When the flash is on-camera the shadows fall behind the subjects where you can't see them.

If you set up light stands, you may get better light, but you will have to be very careful to frame your shots so that the flash shadow is not included in your image.

Also, when using wireless CLS, you have to make sure the small round red IR window on the flash is pointed towards the commander. Otherwise, the Remote may not fire (or it may fire incorrectly).

If you don't have a multiple flash bracket, I think you should use your stands, but keep them very close to the camera, so the flash shadows will be minimized.

James Clark said...

Hi Russ,

I just came across your blog today after doing a search. I had been frustrated with my SB-700 on my D7000. I want to thank you for providing such detailed information. It will be a great help for me! One thing that I didn't see addressed was Shutter Priority. Could I use it instead of Manual? I just bring up my shutter high enough to coincide with whatever focal length I'm using. I look in the finder to see that I've underexposed by 2 to 3 stops and fire the flash. I suppose Manual would be just as easy to use but just courious if it would be okay to use the S mode as well. Thank you, James

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