Originally posted by yeedub Hello, I'm gonna take a year end photo for our pharmacy class. Theres around 150 students and we're going to be inside a lecture hall with a capacity for that number of students. The ceiling is quite high up and lined with wood and isnt white, as are the walls. There is a wall at the front of the lecture hall with large white projection screens.
OK, that's all pretty discouraging. ;-)
Quote: What settings do you think would work the best? So far I have 2 ideas in mind:
Lightsphere, pointed up; 16-20mm f3.5, 1/30s taken from the front of the lecture hall with students standing in the aisles and rows
Flash turned to shoot over my shoulder and off the white projection screens, 16-20mm f4, 1/30s
Equipment:
K10D, DA* 16-50mm, Sigma EF-530DG Super. Perhaps a tripod and IR remote as well.
I suspect you're not familiar with the "
inverse square law." Basically, double the distance between flash to subject, and you end up not with half as much power in your flash but ONE QUARTER as much. Forget the math: what it boils down to is, you can't get very far away from your subject if you plan to light it with a normal hot-shoe flash unit. A single flash unit isn't designed to light an entire room with 150 people in it, even when you point the flash directly at the subject. If you BOUNCE the flash, you're cutting the power in the flash very dramatically. And even if you manage to light the folks in the front row well, you're going to have serious problems with the folks in the back row.
I'm assuming there are lights in the room. With any luck, they'll be bright lights. These lights will probably do more for you than the flash. And with your Pentax DA* 16-50, you can open up to f/2.8 and you might be able to take the photo without flash at all. Be sure to shoot raw so you have more latitude to adjust white balance later.
On the other hand, if you're going to use flash, I'd think you'd need more than one. I don't really know, but I my wild guess is, if I were going to try this, I'd use THREE flashes: I'd put my two Pentax 540 FGZ units on stands to the right and left of the camera. I'd point 'em right at the audience, with just a slight turn on each flash to help widen coverage. (In other words, the flash unit on the left would be pointed toward the center of the room, but then repointed a little bit to the left side. The right flash would, in the same way, be aimed at the middle-right of the room.) I'd use my camera's pop-up flash as a MASTER, with its output cranked up +1. I'd remember to take the lens hood off, so it doesn't block the light from the built-in flash. I'd probably try 1/60thsec as a shutter speed. Go much slower and you have to worry about people moving. If you were going to overpower the scene with the flash, then you could count on the flash to freeze the action. But here, you're going to be using flash to complement the available light. Hmm, 1/60th sec, f/2.8 and, well, whatever ISO you need to get the shot. I'm guessing 400 to 800 should do.
I would definitely use a tripod. I usually put the camera on a tripod for portraits, not so much because I could not take the photos by hand, but because I need to be able to look at the subjects and talk to them while I'm shooting - and I trip the shutter using the remote.
But I'm not in that room and don't know that light, so really, I'm babbling here. Matjazz's advice is the best: Go there ahead of time and do some testing. The problem with this is, photographing empty chairs isn't the same as photographing a room full of people. If you could get a couple of friends to help you out, place 'em spread out in the room, somebody in the back row, somebody in the front, somebody in the middle, a couple of folks on the sides.
Will