Flash Comp

[Bob Shaw]

I made a mistake today and lost some pics due to overexposure. It was very cloudy this morning and needed to use fill flash for a quickly developing scene involving 2 turkeys. ;) I believe instead of entering a negative comp at the flash, I should have done it at the camera... a 50D and a 430EX were used. Of course I notice after the first preview that I was a little overexposed, but kept subtracting at the flash, which was making my problem worse I presume. By then it was to late, so I grabbed my backup camera without flash and snapped off a couple shots. I'm downloading now, hopefully I can save something. Any comments will be helpful. Thanks, Bob

[Fabs Forns]

Did you use High Speed Synch on your flash? Otherwise the s/s would be reverted to the synch of the camera, which may be 1/250 of a second, depending on the light, grounds for over-exposing.

[Bob Shaw]

High speed sync was used... I'm not a total doofus, just partial. :-)

[Charles Glatzer]

Bob, it is difficult to say without knowing more details. Was the ambient exposure correct? How small and different in tonality was the subject relative to the background? What metering mode was the camera and flash in?

Best,

Chas

[Bob Shaw]

Even though my ISO was set at 640, camera metering was set for partial and the darkness of the turkey combined with the lack of light, sent my ss down to 1/60... I was very close to the subject with a 300f4. So the camera was trying to bring the exposure back up to where it should have been, thus overexposing the entire pic. Does this make any sense? It was oviously a situation where the operator didn't know what the heck he was doing. Thanks for bringing these other factors up Charles.

[Alfred Forns]

Hi Bob Your were in partial metering (not recommended) but was the camera in Av, Tv, M ?

We need to know as Chas Asked if you had the correct exposure without the flash? Was was the exp compensation for ambient light?

[Bob Shaw]

I'm sorry I didn't give that info before.... I always shoot AV mode and this morning it was set for f6.3 at that time with 0 EV. There was also quite a bit of difference beween the subject and the surroundings. Thanks for all everyones help. Bob

[Alfred Forns]

Maybe Chas can figure it out !!!

With the given settings I would have guessed just like Fabs did with the HS sync ... but it was on.

[Charles Glatzer]

My guess is the partial meter pattern rendered the dark turkey as a mid-tone....lighter than it should have been, thus over-exposing the subject by at least a full stop if not more. Add to that the flash is seeing a very dark subject and over-exposing as well...even at minus 2. It is always best to assess the ambient light first, setting the exposure to render the subject as desired. Thereafter, you can determine if you need flash and how much. Keeping the two exposures seperate makes the process much easier.

See my post near the bottom of this http://www.birdphotographers.net/forums/showthread.php?t=34070

Best,

Chas

[Bob Shaw]

Thank you so much everyone for all your help! And Charles, I'll burn this info into my memory for all my future situations. Bob