Tuesday, April 1, 2008

12 Speedlight Trick #1

One of the situations I run into regularly is that I am fairly far from a subject who is in a dim ambient setting, and there is something closer to me that is affecting the flash metering. This could be a plant, a wall, another person, a wedding cake, or anything that can reflect the preflash pulses back to the camera.

For example, lets say your subject is standing inside a dim room and you want to shoot a picture of her from outside the room through a doorway. If you simply set TTL on the flash and place the subject in the center of the frame and shoot, the reflections from the doorway will make the system think your goal is to shoot the doorway and you will get a great shot of a slightly overexposed doorframe and the subject will be pitch dark. The doorframe will be slightly overexposed, because it is not in the center of the frame, but it will still cause the flash to reduce power drastically leaving the subject dark.

The trick is to first aim the head of the flash forward and remove any diffusers that don't push the little switch on the flash head (so distance information can be used by the flash). Then switch the flash to TTL-BL and frame the shot and hit FV Lock.

Then, the distance to the subject is used in addition to measuring the strength of the reflected preflash pulses from the center of the frame. The flash sees that the distance is much farther away than the doorframe, so it increases its power accordingly. This usually doesn't brighten the subject fully, but it definitely brightens the subject far more than using TTL. Of course, once the subject is brightened to proper exposure, the doorframe will likely be blown out, but that can't be avoided.

The way to make this trick easy to implement is to start with the camera in manual mode and matrix metering and the flash in TTL-BL. Then, switch the camera to spot metering. That will force the flash automatically to TTL which is usually best indoors in dim ambient. Spot metering doesn't do anything to the camera settings since manual mode has been selected. It only affects the flash mode.

Then, when you run across the situation mentioned above, switch the camera metering to matrix, and the flash will automatically switch back to TTL-BL, and the shot will be exposed the best way possible. However, the flash may still need increased compensation to get the exposure on the subject exactly right.

If you don't want to remove the diffuser, another way to do this is to zoom in on the subject and hit FV Lock. The flash metering system will only look at what is in the frame center weighted. Then, zoom back out to include the doorway or whatever is between you and the subject, and take the shot. Of course, the doorway will be blown out, but that's normally OK in this type of shot.

36 comments:

Anonymous said...

Thanks! Keep it up, I've learned lots from you.

Martin, Sweden

Anonymous said...

Thank you so much for taking the time and effort to put these pages together - I think Nikon should get you to write their next flash manual.

Thanks again,

John, UK

Russ MacDonald said...

To Martin & John,

I'm glad you find my blogs helpful! I often wished someone could have written this stuff for me so I didn't have to learn it by trial and error.

Regards,

Russ

JK said...

Hi Russ,

I found your answer to my email is crystal clear and has removed lot of confusion.

For the tip above, could you explain more clearly, eg step by step? I don't get the point why we should switch to spot metering and back to matrix again? only to dial the flash power up?

Thanks,
Jusuf, Indonesia

Russ MacDonald said...

Jusuf,

Yes. The only reason to switch from spot to matrix and back again is that it is easier than changing from TTL to TTL-BL and back again on the flash. You can switch from spot to matrix and back with your thumb without having to take your eye from the viewfinder.

Since most photographers use the camera in Manual mode whenever indoors in dim ambient, switching from matrix to spot and back has no effect on the camera portion of the exposure. I normally set my camera on f/2.8 or f/3.5 and 1/80th sec for indoor dim ambient flash shots.

Again, the reason for switching to TTL-BL is to force the flash metering system to use focal distance as well as reflected light from the preflashes to determine the flash power. In TTL mode, the reflected light from the preflashes is the only thing used to determine flash power. Distance is not used in TTL.

The reason you want distance to be used is that in the situation I described, there is something nearer to the camera (the doorway) than the subject that will reflect light back and cause the flash power to be too low to properly expose the subject.

I should also mention that there are several ways to handle this situation. One that is used most often is to use the flash in Manual mode and set the power where you want it. The reason for this 'trick' is that when you need the picture quickly, and there is no second chance in case you dial the wrong power, TTL-BL will often get it close enough. You can also zoom in, use Flash Lock, zoom out and shoot. You can also set positive flash ev. But using any of these other methods will often require a second shot to get it right, and there may never be a chance for a second shot.

Russ

Remi said...

Russ, you've just opened the window of FV lock for me. Previously if I'm stuck in this situation I will switch to manual flash and most of my fellow photographer will use manual flash all the time. I believe that Nikon flash system has a way to overcome this issue and I've tried to zoom into the subject and press FV lock. Surely my subject is well lit and normally I'll dial down the flash compensation a bit to balance it with the surrounding area. Thanks again. Before I read this article FV lock is just a Nikon gimmick into making simple things look extremely complicated.

Anonymous said...

Hi Russ, I've only just stumbled on your Blog pages. Fantastic! Extremely informative, yet written in a way even I can understand the techniques. Thanks for taking the time and sharing your knowledge. Karen - Cocos

Russ MacDonald said...

Hey Karen,

Thanks so much for the nice feedback!

Russ

Anonymous said...

"Of course, once the subject is brightened to proper exposure, the doorframe will likely be blown out, but that can't be avoided."

Did you try to set manually the flash zoom head? If you are using a WA lens to get the picture including the frame why not to set the zoom head to 85 mm, per example?

O.Cristo

Russ MacDonald said...

O. Cristo,

There are lots of ways to solve this problem. My point was to demonstrate that you can use the automatic distance reporting feature of TTL-BL to set the flash power for you.

You can also leave the flash in TTL and zoom in on the subject so that the door frame is no longr in the picture, hit FV Lock, zoom back out to include the door frame, and take the shot to achieve the same thing.

I've never tried using manual zoom on the flash, but there might be a way to use that as well.

Russ

Kati van Helden said...

Hello Russ,
Are you familiar with
Lowel ID-Light 100 Watt Focus Flood Light for wedding and other low light photography?
At the moment it is very populair with wedding photographers.
thanks , Kati

Russ MacDonald said...

Hi Kati,

Yes, I am familiar with the Lowel 12V Lights. I don't use them, but some of my friends do. I've seen them used to throw a focused beam onto the formal shots, especially to highlight the bride.

I just don't want any more equipment to have to lug around.

Russ

BMC Photo Blog said...

Hey Russ,

First off, have to add to your accolades...your blog has seriously changed the way I work. I'd been using manual flash all the time, then the Hot Shoe Diaries got me thinking about using CLS (since I paid for it already anyway). But I was hopelessly confused. Now, thanks to you, I am using it more and more. Really appreciate your contribution to the photoblogosphero.

I do have a question...I used a D300 but am sure it would be the same on the D200. I use spot metering a good bit (without flash) so I have my FN key set to spot. I have my preview button set to AE-Lock...which I also use a good bit. I shoot in A mode typically, but working toward shooting in manual more and more.

Do I need to give up my spot metering or AE lock button to set up easy access to FV lock? What happens if I set the FN button up to be both AE and FV lock and shoot in manual? AE lock gets overridden by the manual setting and FV will lock my flash exposure? Is that right?

Of course I don't have the camera or manual handy so not even sure the button can be set to store both AE and FV. But seems that it should be one of the options.

Also, if I use your speedlight trick and set my flash to BL and change my metering back to matrix, then I spot meter using the assigned (DOF) button, does that change the flash into BL mode?

Thanks

Russ MacDonald said...

Hi BMC Photo Blog,

Thank you for the compliments!

With my D200, the only way to fire FV Lock is with the FN button.

That's why, on my D200, I suggest switching between Spot and Matrix by using the metering selector switch. It is easy on the D200 to reach up there with your right thumb and change it. Not sure if this is the same on the D300.

I see in the D300 user's manual that the both the depth of field preview button and the AE-L button can be set to fire the FV Lock pulse using Custom Settings f5 and f6.

It sounds to me like you could put your FV Lock on your depth of field preview button and that would leave your Spot selector on your FNC button, and your AE-L button would also stay the same.

To use this trick, you have to be in TTL-Mode and Matrix metering to begin with. Then when you select Spot metering the flash is forced into regular TTL mode.

If you start off with the flash in regular TTL mode, switching between matrix and spot mode has no effect on the flash mode. It stays in regular TTL.

Hope this helps,

Russ

BMC Photo Blog said...

Hey Russ,

Yeah. That helps. I haven't been using the AE Lock button on the back of the camera (been using the DOF for that function). Will make the switch.

One last question, if I set metering to spot and flash to BL, then switch to matrix (and the flash goes to TTL) and am shooting, will the flash revert back to BL if I spot meter by using my FN key, or only if I turn the actual switch on the back of the camera (which on the D300 is a ring around the AE Lock button)?

Russ MacDonald said...

Hi again BMC,

If you are in Spot Metering you cannot put the flash in TTL-BL mode. It won't let you. The only flash mode that is available in Spot metering mode is regular TTL.

The reason for this is that in BL mode, there has to be metering information information from the background for the flash to balance with. In Spot Metering mode the only information from the metering is coming from the subject, so the flash would have nothing to balance with.

Now, if you start in Matrix metering mode and put the flash in TTL-BL mode, and you push the FNC button to switch to Spot metering, the flash will switch temporarilly to regular TTL mode. Then, when you release the FNC button, the camera will go back to Matrix metering, and the flash will go back to BL.

Russ

BMC Photo Blog said...

Thanks Russ. I was asking it backwards of what I meant...but you answered what I meant to ask in the last paragraph. I will get the camera out tomorrow and check it out.

Abe said...

Sorry to shower you with so many questions, I'm just loving this blog/info too much.


>>If you don't want to remove the diffuser, another way to do this is to zoom in on the subject and hit FV Lock. The flash metering system will only look at what is in the frame center weighted. Then, zoom back out to include the doorway or whatever is between you and the subject, and take the shot. Of course, the doorway will be blown out, but that's normally OK in this type of shot.

This method/trick is this in TTL mode or do you still need to switch to TTL-BL? If this is for TTL then this would seem to be a much superior method, why ever both with the first trick?

Russ MacDonald said...

Hi again Abe,

Yes, that's in TTL mode.

I agree that zooming in is best - if you can do it. But what if you are using a fixed lens? Or what if you can't zoom far enough in to get the door frame out of the image. It's always good to have choices!

Russ

John Meyer said...

Great blog!

Anonymous said...

Hi Russ,

so i use matrix mode to set my exposure to optimum dial 0. and then i switch to spot metering so that the flash will switch to TTL-BL and then take the shot. did i get it correct? thank you veyr much for this information.

benjie

Russ MacDonald said...

Hi benjie,

No, not quite.

What I am describing is simply a quick way to switch the flash between TTL-BL and TTL. This is useful when you are shooting in a situation that has backlighting in some areas and not in others. For backlighting, you always want to use TTL-BL, but for other areas, you want to use regular TTL.

When you select spot metering, it de-selects TTL-BL and forces the flash into regular TTL mode.

This is simply a quick and simple way to switch the flash back and forth between TTL-BL and Regular TTL.

Russ

Billy said...

Thanks Russ for sharing so much info and being so unselfish. Appreciated.
Billy(Kingston, Jamaica)

Russ MacDonald said...

Hi Billy,

I appreciate your kind comment!

Thanks!

Russ

Anonymous said...

Russ you are blowing my mind with how awesome your explanations are. ...Nikon flash manuals kinda suck. Thanks you so much for this info!

Russ MacDonald said...

To anonymous,

Your comment is great feedback!

Thanks!

Russ

Arrovel said...

Russ,
I am new to photography but I am a fast learner and avid reader. Your blog is fantastic and I thank you very much for doing it. I have become a daily reader of your blog as well as the Q&A section that is a nice complement to your writtings, and to my developing as amateur photographer.

For this particular section, would it be possible to have some pictures on this topic, so we can have a better graphic explanation of your trick?

Thank you,
Arrovel
Mc Lean, VA

Russ MacDonald said...

Hi Arrovel,

Thanks for the great feedback!

Yes, I will plan to add an example of this technique. Good idea.

Russ

Frank said...

Thanks for your kind reply to my earlier question. I will definetley email you later. But for now, I have a question about FV-lock, as you use it in this blog.

"You can also leave the flash in TTL and zoom in on the subject so that the door frame is no longer in the picture, hit FV Lock, zoom back out to include the door frame, and take the shot to achieve the same thing."

I did so, but it seems to me, that not only the doorframe, but the hole picture is overexposed. (aprox distance to door: 3 feet - to subject/background: 20 feet)

When i compare how the flash sounds when zoomed in (to get free of the doorway) and how it sounds, when its zoom out, its obvious, that it dumps more power, when zoomed out (this is with the fv-lock value from when zoomed in)

Dont really get this. Shouldnt the output be exactly the same when fv-lock is used? Or does the flash power up a bit in order to cover a wider angle - and still try to keep the same flashvalue for the flash-metered area?

(D50, SB900, 1/60, f2.8, ISO 200)

Regards

Frank

Russ MacDonald said...

Hi Frank,

Your wording is a little confusing, so let me try to explain what happens better.

In TTL mode, the flash sets its power by what is included in the viewfinder.

If you take a picture through a doorway of a subject standing in a dark room, the reflected light from the preflashes from the door frame will by much brighter than the reflected light from the person, so the flash power will be set very low and the person will be dark.

When you zoom in so the subject fills the viewfinder, and you press FV Lock, the flash power will be set to what is needed to set the subject to 'standard' brightness. This power will be much higher than when the doorframe was in the viewfinder, because the reflection from the doorframe is no longer metered.

Then, when you zoom back out, the door frame will again be in the viewfinder, but the flash power will remain at whatever value was locked in when FV Lock was pressed.

This will make the subject much brighter and the door frame will blow out.

The flash power should be the same after FV Lock is pushed, regardless of what zoom position is used.

However, you have to remember that the flash also zooms. This spreads the flash pulse out as you zoom back, and this will tend to make the subject a little darker when you zoom back out to include the doorframe.

If the subject is overexposed after zooming back out, this means that the metering was not accurate when you were zoomed in. Several things could cause this: The subject may have been wearing dark clothing, or the background was dark and it was occupying most of the frame, or the FV Lock function on your camera locks in a value that is too high, in which case, the camera and flash needs to be calibrated by Nikon.

Hope that helps,

Russ

Frank said...

Yep, thats excatley the way, I thought it should work. But what I mean is, that the subject in the photo when zoomed out (including the doorframe using fv-lock) is brighter, than it is, when zoomed in and using the same fv-lock value. (not the other way around)

I thought, it may had somthing to do with the close distance to the doorway, but maybe you are right, that there is a problem with my camera.
I will experiment some more with this, and let you know how it turns out.
Have a nice weekend.

Frank

Russ MacDonald said...

Hi Frank,

I understand now.

It is very common for FV Lock to give a different flash power than when shooting without it. On my D200, FV Lock always underexposes by one stop, so I always increase the FEC to +1 ev whenever I use FV Lock.

On my D3 it is right on. I get exactly the same flash power with or without FV Lock, so I leave the FEC alone.

I have never sent in a camera to have this adjusted. I'm not sure if it can be adjusted or not.

Russ

irvin00 said...

A 'bit' late (2 years!) to this discussion, but wouldn't it be much easier to just get the flash off camera?

Great site, full of very useful information!

Russ MacDonald said...

Hi irvin,

When I am shooting an event like a wedding reception, I normally don't have an assistant, and certainly don't have enough time to take the flash off-camera and set it up. Things move way too fast in events like this, and my little trick works quite well.

If I were shooting a model and had plenty of time for the setup, I would definitely get the flash off camera, and I'd use multiple flashes as well.

Thanks for the nice feedback!

Russ

Steve Wood said...

I have just stumbled across this after struggling to understand the Nikon SB900 manual. This is really really well written by any standard, and is light years ahead of Nikon manuals in general and the SB900 in particular. The simple point that the camera and the flash are essentially independent is so useful to know, but is not made - or at least is not properly emphasised - elsewhere. So - thank you very much.

Russ MacDonald said...

Hi Steve,

You are right! Nikon does'nt explain things very well. In fact, that's exactly why I wrote my blogs.

I'm glad you find my articles helpful.

When reading my blogs, be aware that that I wrote about the SB800 speedlight and the SB900 has a few minor differences. One that comes to mind is that the SB900 has additional modes where the preflash sequence can be eliminated. On the SB-800, you had to know how to do it and understand it (and I wrote about it). On the SB900, (which I do not own) it shows you in the display whenever there will be preflashes.

Thanks for the nice feedback!

Russ