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Projector Screen, Masking and Mount


Screen



The screen was reasonably simple to build. Took some 1/4" flooring plywood and cut it to just over 48" by just over 85". Then cut 2.5" wide strips of 3/4" mdf to line the outer edges of the plywood. For bracing I stuck in three 7" wide by 1/2" strips of MDF (even with all the MDF the screen was still quite light). Four hand holds where cut into the plywood, two of which do double duty as what the 1/4" mirror hooks hang onto for mounting the screen. The screen itself is plain white blackout fabric. I simply followed the instructions on this page to stretch the fabric (I did cloth side out). Good cheap substitute for canvas pliers are flat nose welding vice grips. Oh and a pnuematic staple gun is a must for this job.



Screen 2



The second screen I built is very similar to the first. The big changes are size and construction method. This new screen is a 2:1 aspect ratio that measures 96"x48". The big difference in construction is a switch from 3/4" MDF to 3/4" laminated pine shelving for the frame. The frame was constructed using 1/4" plywood to fish plate the frame edges together. The finished frame was then mounted on the 1/4" flooring plywood to increase its rigidity and make it easier to handle. The center braces were also eliminated. Because of the masking system it was no longer necessary to use mirror hooks to hang the screen. So the hand holds weren't cut this time, instead velcro was stapled to the back of the frame at the corners.



Masking



The masking is really quite simple. Cut a strip of 3/4" laminated pine to the width of your screen, plus a few inches (so perhaps 100" for a 96" wide screen). Then affix black masking cloth to it. This serves as the bottom mask. Your top mask will be a valance that will house a curtain rod for the vertical masks and a roller for the horizontal mask. The valance and the fixed bottom mask will be attached together using two strips of pine such that they will form a slot your screen will fit into. With the bottom mask acting as a ledge you can get away with using velcro to mount the screen into the masking system.

The valance involves framing out the sides and top, coming out from the wall several inches, also with pine. Within this valance, attach a curtain rod. This curtain rod will connect to, and control, the vertical masking. Attach some blackout curtains to this curtain rod, for use as your side masking. Iíve sewn a piece of straight steel (light, but inflexible) into the inside edges of the curtains to ensure they hang straight and therefore forming nice straight vertical masks. If I was to do this again, I'd weight the bottom of the straight edge slightly and make sure it was the straight edge and not the curtain material that connected to the curtain rod. The last step is to add the horizontal masking; this is where things get a little tricky. The horizontal mask is wound on a roller that feeds out underneath the top curtain rod.

This roller is made of 1 1/4" EMT pipe. Iíve hammered into the ends of the pipe a 1/2" piece of circular plywood, with holes drilled in them to accept 1/4" bolts and T-nuts on the inside. The T-nuts are there to provide something very solid for the bolts to screw into. This essentially creates a roller that I can easily set up to rotate. On the side that will not have the cranking mechanism (the left in my theater), thread a 1/4" bolt (one that isnít threaded all the way to the top) through a hole youíve drilled in the outside of the valance, into the plywood in the end of the roller and finally into the T-nut. Donít forget to put a washer, lock washer and nut on the bolt before you thread it into the plywood in the end of the pipe. Youíll use this to lock the bolt to the roller making it so they turn together. The right side will need a little more hardware. Here I recommend using a 1/4" stove bolt (a bolt that is threaded all the way to the top. Again youíll need to drill a hole in the valance to accept this bolt. On this end though, since the stove bolt is threaded all the way, I mounted a T-nut that was too large for a 1/4" stove bolt to the outside of the valance to prevent the bolt from wearing away the wood. Use the same means as the non crank side to lock this bolt to the roller so they turn together. On the inside of the valance, put two nuts (turn them together tightly so they wonít move) and a washer. These two nuts and a washer server two purposes. The first is to prevent the roller from sliding around much side to side. The second is to provide a support for a wing nut on the outside of the valance to tighten against and stop the roller from turning without popping the wooden plugs in the rollers out in the process. Finally rig a simple hand crank to the stove bolt on the outside of the valance. Wind black masking onto this pipe, and sew another steel piece into the bottom of the masking (I used 3/4" EMT pipe for this purpose).


Gray Screen Test Part 1



Below are some pictures of my painting test. High heat enamel silver from Rustoleum is on the left and high heat enamel aluminum from Tremclad is on the right. I didn't take the same amount of care taking these pictures as I did the ones on my current equipment page. They more or less show what I saw on the screen, just toned down a bit. So in other words although blacks don't look that different in the pictures, blacks were significantly improved in the grey portions. However the grey screens also made bright colors, whites, and especially flesh tones, look like there was a haze in front of them in comparison to the plain black out fabric (which like the significant black level improvement isn't coming through completely in the pictures). So bottom line from my testing, the sacrifice made to colors by the grey screens out weighed the improvement to black levels.


Also note that I recalibrated with Avia to the grey screens, so contrast and brightness are up from the plain black out cloth calibration which explains the plumming you are seeing in a couple of the pictures. My guess as to why I haven't had the same favorable results as others with these grey spray paints is I'm painting on the cloth side of the black out fabric while most of the other grey paint success stories are on smooth hard surfaces.


Grey Screen Test Part 2



Background is my plain blackout cloth screen. On the left is the dDog. Middle is the Vutec GrayDove. Right is the DaLite HCCV. The pictures come pretty close to showing what I saw (well at least on my monitor).



Basically the HCCV least effected colors and whites. dDog sometimes looked like it didn't at all, other times it did something undesireable to me. GrayDove crushed some colors, but with proper projector calibration I'm sure that could be undone.

GrayDove made the biggest difference to blacks. HCCV made almost no difference at all to my eyes (one or two fine shades at most). But none of them were what I would call significantly better than the blackout cloth. Especially considering the price and or effort difference.

The biggest problem I had with all three samples was the sheening effect on really bight scenes. The lines that are showing up in the pictures were not apparent to me while watching, but what the camera isn't showing is how that bit of sheen you see moves making it very annoying (at least to me). Possibly the sheen is these lines moving and the camera of course froze them. HCCV was by far the worst for this. GrayDove and dDog where about the same with the dDog being a little better. No sheening period on the blackout cloth.

Bottom line is for me, overall the plain blackout cloth produced the best picture. My brother knows squat about what the screens are supposed to be doing, I just asked him what he thought was the best and he reached the same conclusion.


Mount



I'm not terribly happy with my projector mount, but it's good enough that I won't build another one just yet. It simply consists of a 1/4" plywood base that the projector is mounted to. The roof has a 3/4" chunk of plywood attached to it. The tube is a box made out of 1/4" plywood. The roof chuck and projector base each have a 3/4" piece of plywood cut to fit inside the tube. The roof's 3/4" chunk is mounted with a bolt that allows rotation while the projector base's 3/4" chunk is glued.

I'd avoid copying me on this part, instead check out this thread. I based mine off his but not closely enough :p. Oh, and hunt down the M4 screws early. I thought they'd be easy to find and started to get pretty ansy when I thought my mounting would be thwarted by 4 screws.



Contact me if you have any questions.
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