I'm Confused....

I am experimenting with flash and flash settings (just got David Zisers book) and I am a bit confused at something. It is recommended to underexpose the ambient by 1 to 2 stops when using flash so that the subject is better exposed than the scene. I shoot in manual mode (camera) and iTTL (flash). I set my camera to matrix metering mode and set the overall exposure so that it is 2 stops underexposed. My question is this: When I turn off my flash, my exposure meter changes by about 1 stop. When I turn it back on it changes back (ie when the flash is turned off the meter reads underexposed by 3 stops...then when I turn it on the meter reads underexposed by 2 stops). Can anyone explain why this happens? Also, when it is recommended to underexpose the scene by 2 stops, is that with the flash on or off?

Thanks in advance.

Stephen Elms said:

I am experimenting with flash and flash settings (just got David Zisers book) and I am a bit confused at something. It is recommended to underexpose the ambient by 1 to 2 stops when using flash so that the subject is better exposed than the scene. I shoot in manual mode (camera) and iTTL (flash). I set my camera to matrix metering mode and set the overall exposure so that it is 2 stops underexposed. My question is this: When I turn off my flash, my exposure meter changes by about 1 stop. When I turn it back on it changes back (ie when the flash is turned off the meter reads underexposed by 3 stops...then when I turn it on the meter reads underexposed by 2 stops). Can anyone explain why this happens? Also, when it is recommended to underexpose the scene by 2 stops, is that with the flash on or off?

Thanks in advance.

Click to expand...

Using iTTL, on-camera Exposure Compensation (not Flash Exposure Compensation), on a Nikon affects both the camera and flash exposure.

So let's say you set your on-camera Exposure Compensation Value to -2, and your Flash Exposure Compensation Value to +1. You would get a balanced exposure of -1. Check your flash settings.

It is also recommended to use center-weighted or spot metering, not matrix.

everything should be in manual mode - camera and flash. you can use the camera meter to get ambient (aka fill) light and then a flash meter to set the flash's exposure.

when you begin to add more flashes you usually use one of them as fill so the camera meter becomes useless as ambient isn't a factor in the exposure anymore.

you need a flash meter to work with flash at anything other than one flash basic stuff. Once you get experienced and skilled you can do a lot without a meter as you get a 'feel' for it. I can get w/i 1/2 stop of exposure (ambient lighting) with no meter at all just from experience but often with flash I use my meter to double check the ratio's and such.
--
If I knew how to take a good picture I'd do it every time.

working VERY well for Stephen, as he has some fantastic shots on his site.

I use TTL when I'm using on-camera only flash. As soon as you start to mix flashes they start to think too much and make their own decisiions. I get inconsistent results - too much output from a flash this shot and too little the next.

You can see this same thing happening in AV mode on your camera in many instances. Walk around a room and take a few exposures. You'll see the exposure change from shot to shot as the camera seeks to make the scene 'middle gray'.

That's exaclty what TTL flash is doing too. You can use FEC to tweak it, but shoot a guy in a white shirt with a black jacket and toss in a rim/hair light that's eTTL and see what wierd things you get. The rim light sees black so it pops off hot. The on-camera or main see the white shirt/skin and pops low. Now have him take off his jacket for a shot or two and things change again. And don't dare put a reflective surface in the line of site (often jewelry will cause issues).

Gimme manual where i can get consistent, predictable results every time.
--
If I knew how to take a good picture I'd do it every time.

With one flash it behaves itself quite nicely, especially if set -2 or -3 to give the barest amount of fill.

With multiples I went wireless manual, as even CLS in manual was hit and miss on triggering the remote flashes.

But whatever flash method Stephen is using, he is getting great results.