Off-camera flash setup

[gwc1023]

I'm going to try some off-camera flash shots at a wedding reception I'm doing in a couple of weeks. I set up my flashes in the basement just to get a bit of an idea what type of settings I could start with when I set up at the reception hall.

I had the lights off in the basement (there are a couple of little windows) - it metered at 1/5sec f/5.6 at ISO800. I got things set up (two flashes on opposite sides of the room) and adjusted, got a good exposure around 1/125 - 1/200 (still f/5.6, ISO800).

Am I correct in thinking that at that shutter speed the ambient light isn't contributing much to the image and so even if the dance floor at the reception is darker, I won't need to change my settings much?

Thanks.

[Lotto]

You are correct. I would try to adjust the lights and not to use iso800. At f5.6/iso800 some room lights will show up in the images, plus it's bit noisey for your XT at iso800.

What lights are you using?

[gwc1023]

I've got an old Pentax flash which I was firing straight up with a version of the better bounce card on it (it seems way too harsh and bright fired straight on) and then my 580.

If I go down to ISO400, I would need twice as long shutter speed for the same exposure, correct, so 1/60 - 1/100?

[lmulderi]

I think you're right about the shutter speed but you should still be fine at even 1/60th...