Flash exposure

[Syx]

I feel a little shameful asking this simple a question, but I couldn't find the answer via search!

When taking flash photos, I sometimes find that they are overexposed. Indoors I usually have to manually tune down the flash to avoid it being quite so harsh, however the occasional photo will be overexposed - the same photo in the same location moments before/after is fine.

Is ther esomething fundamental I'm missing? Flash photography is not one of my fortes!

 

[ryanyboy]

Are you letting the flash recharge between shots. If you're taking them in quick succession this will cause exposure differences very often.

Also what exposure mode are you using - Apperture priority perhaps? Is auto ISO on?

 

[Syx]

I'm letting the flash recharge - and in any case the fact that the brighter shot can follow a normal one doesn't follow...

ISO is usually at 200 when using the flash, and thinking about it I've only noticed this happening when using Programmed Auto.

 

[HoppyUK]

Are we talking about the pop-up flash used in iTTL mode?

It could be lots of things but having to use a little bit of flash exposure compensation is not uncommon. However, if the subject is off centre, the flash will try to expose for the background resulting in over exposure of the main foreground subject.

There will be a function to control this, Canon calls it Flash Exposure Lock, whereby you frame the pic with the subject in the middle, press the FEL button which fires the pre-flash and locks the setting, then recompose the shot as you want it. Then for the main exposure the flash fires at the right output.

Post a pic with your camera settings and we'll be able to see what the problem is for sure.

 

[Syx]

Thanks Hoppy - I'm talking about with an SB600 with iTTL. Chances are that I've deleted the photos in question during a quick chimping session but if I do have one (or I get another) I'll post it up.
I was using spot metering at the time, which as you've suggested may well be the cause.