Flash Exposure Compensation

[azpix]

Does Flash Exposure Compensation just lock the flash at a specific level of power? am I off on this?

when would one use Flash Exposure Compensation?

Thanks,

[fi20100]

The FEC (flash exposure compensation) does not lock the flash at a specific level of power, but you can increase or decrease the flash power relative to what the camera meters it to be.

[DavidW]

Flash shots are two exposures in one - an ambient light exposure and a flash exposure, even though sometimes you choose shutter speed, aperture and ISO such that the ambient light exposure is so close to nil as to be ignored. With that understanding, it then makes sense to say that Flash Exposure Compensation (FEC) is to the flash exposure as Exposure Compensation (EC) is to the ambient light exposure.

The classic use for FEC is to set up true fill flash - where you typically have -1 1/3 or -1 2/3 FEC dialled in. However, there are other times you use it - when using my 580EX (rather than my Qflash), I find that if I'm providing most of the light for the shot, I typically have some positive FEC dialled in. Yesterday I was shooting some test shots of some flowers, experimenting with two flashes and a reflector - that needed -2/3 FEC dialled in to avoid blowing out the white petals.



David

[Jim M]

FEC is Flash Exposure Compensation, which does exactly that – it produces a flash that compensates for some unusual condition or the other. It allows the camera's meter to give you more or less flash than it thought you needed. Common examples are using the flash as fill where you only want to lighten the shadows a little rather than overcoming them entirely, or using it when a subject that has primarily dark or light tones that the meter wants to make medium gray, or DavidW's example where most of the scene is normal, dark, or light tones and the actual subject is bright or dark with a normal background or one of the opposite tone. It can also be useful when the subject is normal against a bright or dark background and the camera can't seem to figure it out. The latter doesn't happen very often in my experience, but it sure can.

Without a bunch of experience in the conditions under which you are trying to shoot, the easiest way to tell if you need FEC is to look at the image you just made and see if you need to do something different. The bottom line is that most of the time you won't need FEC unless you shoot a lot of pictures under one of the conditions mentioned.