Posted by Nappy on 01/14/06 16:10

"William Davis" <davisbill@mac.com> wrote in message
news:davisbill-469360.00141914012006@news.west.cox.net...
>
> Initially I thought I'd need brighter projection to match the inherent
> light loss of rear projection so I went with big powerful projectors -
> 3000-5000 ANSI lumens.
>
> Big mistake at least at the scale I was using. (30 ft diagonal screen.)
> and in a fully light controlled studio.
>
> Turned out the big projector was overkill. I had to light the heck out
> of the foreground talent to balance the images.

Intersting Bill. Was there anyway to limit that output? I noticed you
mentioned ND below for the other projector

>
> Moved to a setup where we stacked a couple of lower output projectors
> 1000 - 1500 ANSI and registered them into a single image. Then, if we
> had a very dark scene that needed more punch we could use both
> projectors and if there was a very bright scene, we could kill one.

Not a bad idea.. did you have to tweak the alignment of the 2nd projector?


>
> We also kept a lot of 1 and 2 stop ND film around to slap in front of
> the projector lenses if I needed a quick fix to dim the background
> image. (the projectors sometimes have rudimentary �brightness� controls
> but they take time and menu shuffling to use and having a bunch of
> pre-cut 4x4 ND squares you can slap in front of the projector lens is
> WAY easier.)
>
> I also found that the GRAY RP screen material we got from Rose Brand
> gave a much more natural video image than their WHITE for what it's
> worth.

Good info.

>
> In all of this the RP looked very dull to the naked eye, but read as
> much, much brighter on video. As always, no substitute for a well-setup
> monitor on set and someone with experienced eyes!
>
> As to projecting Greenscreen, my untested concern is that a rear
> projection setup would be essentially shooting a lot of green light at
> your talent from behind and and I wonder if that would cause
> substantially MORE spill problems than shooting white light at a �matt�
> surface as in done in traditional green screen.

My thought also. I'd like to try it with some control over the screen type
and light. We used to work with 90Ft internally lit blue screens and it was
a trick to balance the screen with the scene. I remember being sick to my
stomach if I didn't wear those amber glasses. :)


>
> You might need MORE opposite color wheel light rimlight for the talent
> to counteract the green spill. Or it might work great. Be an interesting
> experiment.
>
> Let us know how it comes out.


Excellent , valuable information Bill. Thank you for posting. I will forward
this to the crew.

nap.

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