Manual shooting with flash

[wibbly]

In Feb I will we taking pictures at a charity ball, of guests. They'll be paying for a print on the spot from a small Canon 6x4 dyesub printer. That part worked fine last time I did it. It was even quick enough. The setting will be a pre-frabricated 'booth' at the event.

I'll have a 20D with a 420EX flash on it, bounced, and supplimenting some fluorescent lighting already there. This did work ok last time too with a LEE 244 PLUS GREEN filter over the flash and the camera set-up to fluorescent white balance. I took a couple of test shots and used fixed shutter speed, auto exposure with a little exposure compensation. I seemed to get away with this with a booth colour that was predominantly white, and a the mix of black/white/coloured clothes. Perhaps at 6x4 on the night it didn't matter too much!

This time I want to do better if I can...

From subject to subject, I will be moving towards/away, and the sujects will be wearing different clothes, of course. Some white and some black!

1. As the "booth" is a controlled environment, presumably taking and using a custom white balance of a grey/white card will help? With the filter on the flash it should be nearer than otherwise to the flourecent lights. It will always be bounced off the same surface, so my presumption is the overall colour balance shouldn't change too much shot to shot. I'm presuming this should be better than the last appoach of nailing it to fluorescent WB anyway.

2. Is it sensible/is ther eany point in setting up for manual exposure in this situation? Can I expect changing subject distance will mess this up (won't the subject get the same exposure given I'm boucing the flash and there are other fixed lights)? How do I set up the 420EX flash to be fully manual and dial in the power (do I need to), or can I only set up flash comp with the flash insisting on auto exposure? What does a 420EX do when the camera's set on M? Should I just follow my previous appoach above?

W

[tim]

1. Yes - CWB is the best choice.
2. Do you mean M on the flash? Not if the subject distance is changing, plus the 420EX doesn't have a manual mode. If you mean M on the camera then yes, since the flash will be your main light that will be best. Instead use FEC, for someone in a light color try FEC+1, for a dark color try FEC-1. For a mix set it to 0 and hope for the best!

I wouldn't be happy providing photos like this. What i'd do is have two flashes in a master slave setup. Put a 550EX or 580EX on the camera, set it to master, put the 420EX on a tripod, pointing into a silver umbrella, and put it a little to one side of the camera. Put the 420 on channel B, set the A:B ratio 1:2. That will get you nicer photos, and you can use flash white ballance instead of relying on horrible fluro bulbs and CWB.