I'm not a pro and certainly not a "Wedding photographer" but when friends of mine got stood up by their hired photographer I did my best to bail them out. I'm pleased to say that 2/3rds were keepers (after a bit of Photoshop post-processing, of course), but during the course of the [flash] shooting, I was constantly struggling to "get it right", changing parameters on the fly. One [flash] shot was over-exposed, the next under, etc.
For the most part, I used my Lumiquest Promax diffuser (with white insert) and I would have used it the whole time, but I got caught with a few badly-under-exposed shots which made me resort to:
- changing my 580 EX I's EV to anywhere from +1/3~+1 Stop
- abandoning the diffuser. That is, until I couldn't stand the harsh lighting anymore... sigh.
The other downside of the diffuser is that I didn't even manage to finish the the Church ceremony before my fresh set of AAs (Duracell's ultra line) were red-hot and pretty much useless.
Flash-wise, I had my 580EX I set to E-TTL and the default "zoom" setting for the flash is 50mm when in bounce mode (what shouldn’t make much of a difference due to the diffuser anyways). I prefer to work in Av mode so I set my 50D (via a cFn) to work with a range of 1/60~1/250 in Av mode. Metering was in Evaluative mode [(o)] This pretty much covers the entire frame, but in the sample below, the subject took up the entire frame anyways. Ditto for the "potential" back-lighting issues.
So I'm at a loss here... as you can see, my "pre-test" shot was more or less properly exposed. I did move from a 35mm to 55mm range; I'm not sure what that translates to in terms of physical distance from the subject, but I find it hard to imagine it would have been more than 1~2m difference... . Any educated guesses are welcome with particular emphasis on how to best avoid this (i.e. always FEL, or Ev+1 or use Center-weighted or Partial, etc). also is it the general consensus to keep the 580EX in E-TTL mode when "bouncing" or otherwise diffusing the flash?
Thanks a bunch
p.s. Photoshop is my savior... once again... .