Low budget alternative RP screen material

[manuallyfocused]

Hi all,

I'm designing the set for a production in June at a summer stock theater and the director and the management of the theater are intent on using projections as part of the design. I have little experience designing for projection, but I've put together a design that they like a lot. However, there is no room in the budget to use Rosco Twin White RP screen, which the projection designer spec'd as his preferred material. My TD has suggested using white Poly Cyc from rose brand as a low-cost alternative, but noone involved has experience using that particular material. I'm concerned about projector hot spots, usable viewing angle, and relative brightness with any alternative material, but have no experience to draw on that could point me in a better direction.

The setup:
We are using two projectors provided by the projection designer, roughly 6000 lumens apiece, to light up two screens on either side of the stage at a 30 degree angle to the audience (the set forms a shallow V- one screen is roughly 12' x 7', the other is roughly 14' x 8'). The screens are mounted behind scrim-covered scenic walls, so that when images are on the screens the walls go transparent, and when the projectors are off the walls go opaque.

Any advice on possible materials to look at would be extremely helpful. Ideally they would be at least 110" wide to allow for seamless screens. Thanks very much in advance for any and all help you can provide!

 

[museav]

Is there a reason you were considering Twin White, which is a front or rear projection material, rather than a straight rear projection material? Although it does provide a very wide 160 degree viewing angle, in rear projection Twin White has a gain of 0.35, meaning only 35% of the light hitting the screen is transmitted and that is without accounting for any further reduction from the scrim in front of the screens that is apparently planned. Compare that to the grey rear projection material with a viewing angle of 120 degrees and a gain of 1.55 and you get a narrower viewing angle but over 4 times the image brightness.

I do not think the poly cyc would work well, maybe for front projection but not for rear projection. Also consider that the price Rose Brand lists for the projection screen materials is with grommets, finished sides, pipe pocket, etc, while I believe the cyc price shown is just for the raw material.

 

[JChenault]

The cheapest approach would be white muslin. You will see a hot spot from the lens, but you can't beat the price. You can pretty easily set up a screen and see if it is bright enough for what you are doing. Can you position the projector so the audience will not see the hot spot through the screen?

If you consider going with the Rosco gray screen as museav suggests, take a close look at your viewing angles. What the 120 degree number means is that the light gets spread up to 180 degrees when it goes through the screen. If your projector is close to the screen, you will likely find that the image near the upstage of the screen may get very dim. ( IE my gut feel, which I can't verify without more information, is that you want a RP with a wider dispersion due to the fact that the screens are not more directly facing the audience.

 

[manuallyfocused]

The projection designer spec'd the twin white as his preferred color, I believe because of the angle of the screens to the audience. Using the grey would concern me because we do have to have a pretty wide angle of view in order to allow most of the audience to see the images clearly. Also, I'm looking at the price on their website, which I believe is just for the raw material. They offer a custom quote option for finished screens with grommets, seams, etc.

We can place the projectors off-axis, either above the sightline or to the side of the main sightlines, which will mitigate the effect of a screen material that allows the source to shine through.

The projectors are not going to be too close to the screens, we have about 16-18' worth of throw distance so we should be okay as far as having relatively even brightness across the screens. I have gotten a pretty negative response from the production team on the poly cyc material, and we are now looking to a material called Tendo, also from Rose Brand, which is a flame retardant stretch fabric that apparently will be superior to muslin for this application. It can be found here: 122" Tendo, <span style='color:red'>IFR</span> from Rose Brand

Does anyone have experience using this material?

The other thought I'm playing with is using semi-opaque white plastic sheeting. I thought this might solve the issue of seeing the source because it doesn't have a weave. I used some in a show a few years ago and it lit beautifully from behind, and it seems like it might work for projection. Any thoughts on this? Flame retardancy apparently isn't an issue for this theater.

Thanks again for all your help and advice!

 

[derekleffew]

... The other thought I'm playing with is using semi-opaque white plastic sheeting. ...

Probably too small for this application, but some members have reported success using shower curtain liners as cheap, down and dirty RP surface.

I've always found it interesting that Rosco's RP material is nothing like that from Da-Lite, Screenworks, Stewart, et al.

 

[herbiethemisfit]

I can second the shower curtain liner as a low budget alternative for rear projection. I'm working on a show now that we spliced 2 of the $3 WHITE (not frost) shower curtain liners from WalMart to create a 10' wide screen. We've only got a 2500 lumen projector about 12' back, but I was very pleasantly surprised to find NO hot spot from the source. We stretched it over 2" PVC frame and that got rid of 90% of the wrinkles. It's not ideal but certainly functional.

I don't know how it will work with a brighter projector - or on an angle for that matter. Nice thing is they are uber-cheap to experiment with. Size could be an issue. The ones from wally-world are only 71"x70", although you can find some larger ones on the interweb. Also, you have to find a way to hide/deal with the stupid little magnet pockets at the bottom.

 

[sk8rsdad]

If your design could accommodate FP instead of RP then you would have a lot more options.

 

[museav]

I've always found it interesting that Rosco's RP material is nothing like that from Da-Lite, Screenworks, Stewart, et al.

Agreed, but they are much more like the flexible rear projection diffusion materials from Draper, Da-Lite, Stewart Filmscreen, Hurley, Harkness Hall, etc. than some of the materials being discussed as alternatives, which actually seem perhaps more appropriate for front projection.

Do you have 16'-18' of throw or of total depth? Even if that is the actual throw distance rather than the overall depth, which with the projector depth would make the throw shorter, a 12' to 14' wide screen with 16' to 18' of throw would seem to be anywhere from a 1.5:1 to 1.14:1 lens. That is not something the standard lens on every 6,000 lumen projector supports. So I would verify the throw distance with the projectors and lenses you have because if you are worried abut the screen cost then the cost for other lenses may be a real problem.

 

[Dionysus]

Once for a show at College we did not have the budget for the V shaped whole-stage projection screening called for in the scenic design so we tested a bunch of alternative materials for RP. We had four projectors as far away backstage as possible, and ended up using a construction material called TYVEK, which we found a supplier that would sell us a large quantity of without any logos or anything printed on it. (it is commonly used to wrap the exteriors of houses, or to make "those paper suits").
There is some texture present however but the surface was far away enough from the audience with bright enough projectors that it was not noticeable.

It was pretty cool. Saved us a LOT of money on the screening.

 

[manuallyfocused]

museav- we have at least 18' of throw distance (from the front of the lens to the screen), depending on where we place the projector. The projectors themselves, along with wideangle lenses if necessary are being provided by the projection designer's parent company, so those are not a budget issue.

Unfortunately, the design really doesn't lend itself to FP, as I've pushed the set as far as possible downstage to bring the action towards the audience, and the theater has a relatively low proscenium and an angled overhang above the apron, making any projection coming from the house have to be at a pretty flat angle, which would potentially create ugly shadows from other scenery and actors onstage.

The tyvek sounds interesting. Any idea who the supplier was or how one might go about finding another one?

Thanks for all the help!

 

[manuallyfocused]

After much wrangling and a few cuts (and a really good quote from rose brand) we're going to be able to afford the Rosco Twinwhite material for the screens. thanks so much to everyone for all your advice!