Shooting toward a projector

Eric Wenocur


I'm hoping people here might have some insights for a peculiar situation I'm trying to work out...

Imagine a large room, say 40ft wide x 30ft long x 20ft high. There is a video projector out in the
room, aimed at one wall creating an image about 25ft wide x 14ft high (roughly 16x9), starting at
the floor. It's 6-10ft from the wall, and bright enough to allow ambient light in the room (so not
a movie theater).

Assume that the projector is mounted from the ceiling, and offset vertically so it's at about the
top of the 14ft high image. It has a short-throw lens, so it's creating a light "cone" or
rectangle, that has a steep slope heading down to the floor.

There's a camera shooting into the room, about 4ft off the floor and backed against the wall that
has the projected image. The camera has a large imager, and a short focal length lens so it can
pick up a pretty wide scene, also in 16x9.

So it's like shooting a scene with a very bright directional light about 10ft away and 10ft above
the camera height. The camera isn't looking at the projector straight on, but will certainly get
hit with some amount of light. Is there a way to determine how bad the spill will be hitting the
camera? For that matter, would some kind of matte box be able to shield the lens from the projected
light coming down at a steep angle? Or is it a case where if the camera is within the cone of light
from the projector it's just going to get blasted?

Eric Wenocur
Lab Tech Systems
301-802-5885 cell