Flash exposure compensation (350d)

Janice

Janice

Suspended / Banned
Messages
11,626
Name
Janice
Edit My Images
Yes
Can anyone tell me if I put the FEC (flash exosure compensation) down to -2 in the camera settings................ and I put external flash at a minus setting also, does it double up, or does one override the other?

Also., my conservatory is so well lit with natural light on 2 sides and has a white upvc wall on the third side, and an opaque polycarbonate roof . When I take a photo without flash it has a virtually identical histogram as when I use the sigma flash. Do I really need to use the flash then? or would it just be a case of using the flash to get a catchlight in the eyes (i havent checked yet what the windows do to the catchlights).

Any help would be appreciated.

Janice
 
AFAIK the flash setting overrides the camera setting.

Using fill flash will help bring out the shadows a bit but if there enough light for a good exposure the flash power will be knocked right back. Try shooting in manual mode and set the exposure for -1, -2/3, -1/3 and you'll see the effect the flash is having.
 
It doubles up Janice, although thats the wrong way to think about it...both settings on the camera and flash will take effect.

To be using exposure compensation in the camera then you must be using an auto mode anyway - AV SP or P? The whole point of ETTL exposure is that it attempts to balance the flash with the ambient light. If you set exp comp of -1 stop (for example) in the camera for the prevailing light, when you switch on the flash all the exposure info, including your exp comp setting in the camera is fed into the flashgun automatically, so the flash 'knows' that you require less exposure and will reduce it's output according to your camera settings. It may or may not get it right, but assuming your ambient light exposure is correct but you're still over-flashed, then you can add compensation on the flashgun to get the balance right.

You can easily prove this to yourself by taking a few test shots and alternately adding exposure compensation to the camera and the flashgun and by seeing the shots get darker each time.

None of this applies of course if you're using the flash as the main or only source of illumination.

It gets a bit cerebral sometimes. :D

It sounds like you can get away without flash at all if the conservatory is that well lit, but take some test shots. If all you need the flash for is catchlights then you should be able to dial the power right down so it has no visible effect on your shots but will be picked up in the eyes to provide those catchlights.
 
Thanks CT...I was actually talking about FEC in the camera not exposure compensation.

I do use manual mode on the camera but i was wondering if I dialed -2 into the FEC...then -2 in the sigma flashgun would it come out like -4?
 
Ah! I must read more thoroughly. :D

Good question. Hang on. ;)
 
It seems the flash overrides the camera. I've just taken a couple of shots, one with -2 stops FE comp on the camera and none on the flash, then one with -2 FE stops on the camera and on the flash. Both identical. :)

Personally I prefer to make the flash compensation on the flashgun and the ambient compensation in the camera.
 
Yes, PxL8............just what YOU said!!! ;)
 
Hmm, I 'll tack this onto the bottom of this thread rather then starting a new one, being a lazy ol git :)

Janice, you say you use your conservatory for studio shooting, but of course you cant bounce light of the ceiling cos its clear polycarbonate, well :thinking:

I'm about to have the same problem, plus I find in the winter it costs a fortune to heat the dam place and of course in the summer it's like an oven, answere:

http://www.smartpoly.co.uk/

Using the silver strips I figure I will have this great big reflector in the ceiling, plus of course cheaper heating :woot:
 
You must log in or register to reply here.
Back
Top