I just came back from doing the video projections for Stephen Petronio's
_Not Garden_ in a whole bunch of theaters all over the place, with many
different hanging positions, etc. We were using two Proxima 950's, which
produce 400 ansi lumens, not terribly bright by today's standards, but
plenty bright to project onto a set of dancers who are wearing something at
least mildly reflective. Some thoughts that might be helpful:
1) The projector & mirror combination works well. This is useful for moving
the image around (it distorts, which can be cool), and also useful for
getting a hang position where you couldn't otherwise. For example, you can
hang a mirror down from the grid (what is it that you folks are calling a
grill?) unobtrusively, and put the projector above the grid where it's easy
to focus and isn't a huge mass in the audience's line of sight.
2) You can run video over shielded coax cable pretty far (most I did was
150 meters) around a theater with little signal degradation, even when it's
close to electric lines.
3) Watch out for grounding loops.
4) Projecting onto the floor works well. Onto black dance floor (marley)
works very well. The brightest effect is achieved by getting the correct
angle: if you can project from behind, bounce off the floor so that the
bounced image is right in the audience's face.
5) Brightness of your projected image has a lot to do with how big the
final image is, and not much to do with distance. A smaller image from 100'
away is brighter than a larger image from 30' away.
6) Very steep angles seem to help a lot with getting a brighter image off
of a not-very-reflective surface. For example, we had to project onto a
scrim with lighted dancers behind it. An angle of 35 degrees or more was
optimal for getting the brightest image, where shooting straight onto the
scrim was quite dim. Unfortunately, as you can imagine, you have quite an
issue with keystoning at an angle like that.