Rear Projection Small Throw Distance available

tackytec

Member
Joined
Apr 27, 2012
Location
Austin
I am a high school theatre teacher and I have been researching projectors, projections and specs, but I'm more confused than ever about what I'm looking for.
I would like to purchase a projector to use to create some backdrops for a variety of shows including our Fall musical. I know I'm going to need to make some major lighting adjustments to make that happen. I have plans to adjust for that. What I need help with is what projector might work in our space and if it's possible.

I would like to rear project unto our cyc or scrim. Unfortunately our cyc is 4.5 feet from the back wall of our stage. The cyc is 19' (h), 61' (w). I could definitely build some scenic at the base to lessen the overall height I need to fill and bring in curtains/add scenic to stage left and right to decrease the width as well. Ideally, I'd like to fill as much as possible. I do not have a batten behind the scrim, but I can mount the projector on the back wall if needed.

Do you have any suggestions on where to start shopping for a projector? Is it even possible with only 4.5 feet? I know I want as many lumens as possible and presumably an ultra short throw lens, but that's as far as I've gotten on my own. Any suggestions are greatly appreciated.
 

DrewE

Well-Known Member
Joined
Mar 18, 2019
Location
Vermont
One old trick that might help (especially if you don't need the space behind the cyc for a crossover) is to bounce the projection off of mirrors on the back wall, which roughly doubles the throw you have to work with. These I believe a front-surface mirror would be preferable for image quality, but likely wholly impractical to keep clean and undamaged in a high school theater environment (and indeed most any theater environment).

While you don't need the entire back wall mirrored, this still requires quite large mirrors, costing maybe a few hundred bucks per projector from what I can see with a quick Google check. You do lose some light and some sharpness/image quality to be sure.
 

tackytec

Member
Joined
Apr 27, 2012
Location
Austin
One old trick that might help (especially if you don't need the space behind the cyc for a crossover) is to bounce the projection off of mirrors on the back wall, which roughly doubles the throw you have to work with. These I believe a front-surface mirror would be preferable for image quality, but likely wholly impractical to keep clean and undamaged in a high school theater environment (and indeed most any theater environment).

While you don't need the entire back wall mirrored, this still requires quite large mirrors, costing maybe a few hundred bucks per projector from what I can see with a quick Google check. You do lose some light and some sharpness/image quality to be sure.
That's an interesting idea. I would have to figure out something that is not permanent. Our stage is so shallow that our music groups often perform with the back wall instead of a curtain because they need that extra space.
 

microstar

Well-Known Member
Joined
Jan 19, 2014
Location
Lawton, OK
I am a high school theatre teacher and I have been researching projectors, projections and specs, but I'm more confused than ever about what I'm looking for.
I would like to purchase a projector to use to create some backdrops for a variety of shows including our Fall musical. I know I'm going to need to make some major lighting adjustments to make that happen. I have plans to adjust for that. What I need help with is what projector might work in our space and if it's possible.

I would like to rear project unto our cyc or scrim. Unfortunately our cyc is 4.5 feet from the back wall of our stage. The cyc is 19' (h), 61' (w). I could definitely build some scenic at the base to lessen the overall height I need to fill and bring in curtains/add scenic to stage left and right to decrease the width as well. Ideally, I'd like to fill as much as possible. I do not have a batten behind the scrim, but I can mount the projector on the back wall if needed.

Do you have any suggestions on where to start shopping for a projector? Is it even possible with only 4.5 feet? I know I want as many lumens as possible and presumably an ultra short throw lens, but that's as far as I've gotten on my own. Any suggestions are greatly appreciated.
Is there any possibility of moving the cyc downstage a bit to increase the throw distance? You obviously have some way of clearing it for the music groups.
 

halenono

Member
Joined
Apr 21, 2011
Location
Fox Valley, WI, USA
How important is it that you rear-project? I have done similar things for scenery at the high school I work at. I used two Epson PowerLite 535Ws and front projected them on my cyc from one of my electrics which was about 12-13 feet downstage of the cyc. I was able to get a combined image that was about 55' wide and 15' tall. We didn't have any large set pieces that would go far enough upstage to interfere with the projections, and as long as the actors were downstage 6 or more feet from the cyc there was very little shadowing on the cyc.
If you do stick with rear projection, make sure you test how well it shows up on the surface you use. You could look at ultra-short throw projectors, but I don't know how well they would rear-project through a cyc or scrim. Additionally you need an exceptionally flat surface for ultra-short throw, so you would need something tensioned with a bar or other means.
 

microstar

Well-Known Member
Joined
Jan 19, 2014
Location
Lawton, OK
Also, what is the color and finish of your stage floor? Even if your actors are a reasonable distance downstage of the cyc, the bounce from your acting area lights will also tend to wash out the projected image.
You will probably need far more projection brightness than you realize, especially true if you are rear-projecting on fabric that is not a true rear-projection surface.
The suggestions to try front projection are well worth considering, and will still let you have crossover space upstage of the cyc.
 

gafftaper

Senior Team
Senior Team
Fight Leukemia
Joined
Jan 2, 2006
Location
Seattle, WA
I have 13 feet between my back wall and the point where I want to hang an 18' x 32' rear projection screen. I researched everything and there was just no way to do it. I had Panasonic reps come on site and check it out. We figured with their widest projector and lens combo if I placed the projector at the screen and fired backwards into a mirror it might work. But it was a $50k+ gamble and I would have had to come up with a crazy system for the mirror. After a ton of research I gave up. Start saving for a video screen.
 
  • Like
Reactions: Jay Ashworth

ruinexplorer

Sherpa
CB Mods
Premium Member
Fight Leukemia
Joined
Jul 16, 2005
Location
Las Vegas
Are you going to be creating your own content or renting? If you are renting, you likely will be getting 1080 content (or some other standard format). Your cyc is not going to match that. So, yes, masking some of the cyc will likely be necessary. While it would be possible to rear project on the cyc, you are going to lose a lot of your image as much of it will be reflecting back towards the projector. If you are not using a rear screen material, you lose a lot of the benefit of using rear projection.

If you are going to be creating your own content, that aspect is so far outside of what is standard in any projector, it would require blending of multiple projectors to make it happen. I don't know if that would much benefit your productions. The best bet is to utilize what you can from a single projector. So a 16:9 image would end up being around 34x19. If you want to fill the full width, yes, you would need two projectors. But, do you really need to? Were you renting drops that always filled the back of your stage or did you mask the sides?

As a rule of thumb, I recommend 50-70 lumens per square foot of the projection surface (this helps to balance with ambient light as well as various content on unknown surfaces) to have a decent quality image. For an image to decently stand out at this size, you should be considering at a minimum of 30,000 lumens. Now, this being said, you may put up a projector with 7,000 lumens and be perfectly happy. This ultimately results in what you are happy with (between content and its visibility).

What I try to encourage those who choose to use projection is to first think about what it brings to the production. What will it do to help drive the story? When moving lights became available to more than touring concerts that leased them, everyone wanted to add them to their show. Without knowing how to really use them, they were often used in replacement of a light that would have been much less expensive, or as a flashy object that took away from the production because it was being used to justify having it. Now, as more understanding of how they can be used effectively, there is a nice balance in many productions that use them so that they are a seamless tool that helps to drive the story. They can still be used poorly, but that comes down to expeience.

If you can rent/borrow a projector, even if it isn't "exactly" right, do so and experiment with your space. Look at different positions that you might want to place it for a production to see how the image changes. Project from the rear and from the front (make sure your image is the same size) to see how much light you lose. Project from an off axis position (from a wing) to notice the amount of keystone and what happens when you correct that. Then start to add some stage lights and watch what happens to the quality of your image (note: contrast is equally important as brightness in the quality of the image). Take note of where you might be able to mount your projector. What kind of obstructions are present (including performers)? How will you get signal to the projector? How will you control it?
 

Users who are viewing this thread