Rear Projection

[Jon Majors]

Can someone walk me through what I need to know in order to effective use rear projection onto a scrim? I've never done it before and want to know what I am getting into before I make purchases/rentals. Any photos for inspiration would also help!

 

[TimMc]

A big hot spot right on axis with the projector.

 

[FMEng]

A big hot spot right on axis with the projector.

I never tried it, but it seems like that would be a problem. The other issue will be having enough distance from the scrim, and the correct lens, to get the image size you need.

 

[Jay Ashworth]

A big hot spot right on axis with the projector.

Project at an up-angle, enough that the hotspot isn't wide enough for people to sit in front of?

 

[TimMc]

Project at an up-angle, enough that the hotspot isn't wide enough for people to sit in front of?

"On axis with the projector. " Pointing up / down is an option.

 

[Vince]

I never tried it, but it seems like that would be a problem. The other issue will be having enough distance from the scrim, and the correct lens, to get the image size you need.

I've not done rear projection on a scrim, that said I have some experience with rearprojection on a screen. The hotspot can there be a problem, which can be handled by putting the projector low behind the black curtain (how do you call that?) under the screen so the public can't see the projector.
Distance can be handled in two ways. With a short throw beamer but they tend to be low in lumen.
So when I have to turn our gym into an auditorium for the graduations I use a mirror. The beamer stands below the screen, behind that curtain and points away from the screen into a mirror which puts the picture on the screen. It nearly halfs the needed distance, although still more then a short throw would need.
Two pictures, from our graduations in 2019 and 2022. The hotspot in the latter is part of the picture ;-)