8mm Forum: Building a Projection Screen w/ Adjustable Masking?

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Posted by Evan Samaras (Member # 5070) on May 28, 2016, 01:48 PM:

I am planning on building a projection screen with adjustable side masking that will allow me to project from 2.35:1 (scope) & 16:9 (for digital projection/TV) down to 4:3 (flat).

I have some ideas but hoped that some brainstorming from those with more experience and maybe even those with a similar set up can contribute to my upcoming project.

I plan to use 4 pieces of 2x4 that I will use as the frame to attach (with an industrial stapler?) the blackout screen. As for the adjustable side masking I was looking into various ideas such as curtain tracks to allow me to adjust between the three sizes. I will need some kind of clip, magnet, or stop to pull the masking to the appropriate mark. Any thoughts or ideas here would be greatly appreciated.

I was also looking into various forms of masking. From my understanding certain velvet fabric may work well, but I am open to suggestion! I would also appreciate any adhesive suggestions, or any types of adhesive that might be best to avoid? Any suggestions of where to buy the fabric?

Lastly, while I have an idea of the screen size I am aiming for, and have measured for the projection distance I have one question for which I could not find a straight answer. While I want to maximize my screen size, I realize that if the screen goes from wall to wall it will probably make for a poor viewing experience. Is there a certain distance I should maintain from end of screen to wall? Maybe a formula that could help me calculate the distance?

Thank you in advance!

Posted by Maurice Leakey (Member # 916) on May 28, 2016, 03:27 PM:

Evan

A screen should occupy no less than 30 degrees of the field of view. The optimum viewing distance is 1.5 times the width of a screen.

As regards masking, it is important to use a non reflective material such as black velvet, preferably suspended from a curtain track. This makes it easy to place in the required format position.

I am not sure what size screen you intend to use. You could, as I do, employ a permanent roll up screen. Mine is a blackout blind, although it's termed "blackout" this is purely that they are thick and exclude all light. I, of course, bought it in white.

It might be preferable to set up your projector and lenses you are going to use and perhaps show it on a wall to get some idea of what you will able to achieve.

Posted by Paul Adsett (Member # 25) on May 28, 2016, 03:41 PM:

Well I can tell you right off the bat that the time and effort it took me to incorporate motorized masking, and screen drapes, has more than paid off in terms of creating a really professional film presentation and home theater ambience. Not that it cost much at all to do it.

1. My screen size is 115ins wide and 49 ins high in the 2.35 scope format

2. This gives me about 2ft on either side for the curtains(pulled back) and (pulled back) masking panels.

3. Both the curtains and masking panels hang from standard sash-cord type curtain rods. There are two sets of rods running the full width of the room, and hidden underneath the pelmet. The rods closest to the screen are of course used for the screen masking panels. The rods furthest out from the screen are used for the burgundy colored drapes.

The masking panels are designed for very light weight, in order to minimize loading on the curtain rods and curtain motors. Each panel is 56 ins high x 18 ins wide, and was made up from a rectangular wooden frame, made from 1/2 ins x 3/4 ins wood strips. The frame was then covered, on the front side only, with matt black velvet cloth, using Scotch double back mounting adhesive tape. This way you can first spray the frame matt black, then on the innermost edge of the frame, mount the cloth right up to the edge of the frame. This way you get the sharp edge of the frame on the inside edge of the projected picture, and the black velvet gives zero reflection- much better than matt black painted wood. The masking panels hang from the curtain rod as follows:

a) The top of the inside edge of the panel is bolted to one of the holes in the traverse rod carrier.

b) The outer edge of the masking panels hangs from one of the plastic eyelet runners in the curtain rod, using a turn-buckle , which can be rotated to get the inside edge of the panel absolutely dead vertical (really handy!)

4) The masking panel curtain rod is powered by a curtain motor. The one I got was only $90.00 and that included an RF remote control! You can adjust the stops built into the motor to get exact 4:3 or 16:9 framing. Works like a charm! One controller can run up to 6 individual motors or light dimmers. The controller can be preset for a hard stop at the 2.35 and 4:3 formats. For 16:9 I just stop it when it gets to the right position.
These curtain motors are. I believe, available in the UK

Posted by Ricky Daniels (Member # 95) on May 29, 2016, 11:09 AM:

Hi Paul,
Fascinating and your screen looks really professional.
Can you tell more about your motors and controller? Links would be good too. I'd like to get my own project going but couldn't find a reasonably priced curtain motor, maybe you have the answer?
Best,
Rick

Posted by Paul Adsett (Member # 25) on May 29, 2016, 12:46 PM:

Rick, the drapery motor and controller is supplied by Smarthome Products in the USA:
http://www.smarthome-products.com/p-283-add-a-motor-80-drapery-controller.aspx

http://www.smarthome-products.com/p-284-add-a-motor-rf-drapery-control-kit.aspx

These are 12v motors operating from a separate 115v transformer(PROVIDED). You would have to provide your own 230v transformer in the UK.

I have 2 motors in my set up, one for the curtains and one for the masking panels. You can program up to six items to be operated from a single RF remote hand set. But you do need a separate RF motor controller for each motor and the remote handset comes with it.
My system is a constant image height set up (CIH)where the image height is the same for all formats from 4:3 out to 2.35 Cinemascope. For wider formats such as 2.55 Cinemascope, and Technirama etc , I have a separate masking panel that rolls down from the top of the screen. My Panasonic AE4000 digital projector has programmable lens memory, so it will automatically zoom, focus, and vertically shift the image to fit the screen for Cinemascope(and up to 8 aspect ratios) at the push of a button.
In fact, this projector can be set to automatically sense Cinemascope films and zoom the lens accordingly.

[ May 29, 2016, 01:52 PM: Message edited by: Paul Adsett ]

Posted by Evan Samaras (Member # 5070) on May 30, 2016, 12:06 AM:

Maurice, thank you for the advice!

Paul, thank you for the detailed instructions! Could I ask you which curtains you used for masking, or what you may suggest? Did you attach a fabric to those curtains/masking?

I have been thinking of using Sy's black plush triple velvet

[ May 30, 2016, 01:44 AM: Message edited by: Evan Samaras ]

Posted by Andrew Woodcock (Member # 3260) on May 30, 2016, 02:56 AM:

Paul's screen assembly here, really is top drawer.
Very very professional indeed! [Wink]

Posted by Paul Adsett (Member # 25) on May 30, 2016, 02:55 PM:

Evan, the curtains are standard 84ins high burgundy drapes that I got from J.C.Penny. In the picture, for some reason, they look black, but they are actually the same color as the window curtains.
The masking panels are covered with matt black cloth from Joanne's Fabrics. Do not use shiny velvet for the masking panels, you must have matt black cloth for total non-reflection.

Andrew, thanks so much for your comment.

Posted by Gary Crawford (Member # 67) on June 01, 2016, 06:57 AM:

I've done the low tech version of masking screen. I took a big piece of plywood....screwed it into the wall. Projected images of various aspect ratios and outlined them. Then I cut pieces of extra wall paneling to make side and bottom masks. My wife put the black felt onto the panels, each of which had holes drilled in them for hanging. Screws with large heads were drilled into the wall for the masks. I painted the plywood with "high hiding white" paint..(now I use Steve Osborne's special screen paint). It has worked great. With the two side masks in, you get the old standard almost square aspect ratio. Remove one of the side masks and you get just about a perfect 1:85 or close to the TV high def aspect. Put the bottom mask on and take both sides off and you get scope. I just lay the masks on the floor against the wall when not in use. Low tech, very cheap, but effective.
Not really good for portable use, of course, but for my screening room, it works great.

Posted by Paul Adsett (Member # 25) on June 01, 2016, 08:01 PM:

That'a a very original idea Gary, and I'm sure. like all masking, that it adds a great deal to the apparent sharpness and contrast of the projected image.
One of the big things I like about powered masking is the very definite WOW factor that you get when the curtains and masking pull out for a Cinemascope film. For that reason I usually show a 4:3 short film first and then power out the masking as the 2.35 Cinmascope logo hits the screen for the feature film.

Posted by Andrew Woodcock (Member # 3260) on June 01, 2016, 08:12 PM:

With that good old 20th Century Fox intro Paul, I can just imagine it! What perfect surroundings you have to watch scope screenings in!

https://www.youtube.com/watch?v=YXWFYPk11GM

sends shivers, don't it? [Wink]

Posted by Evan Samaras (Member # 5070) on June 04, 2016, 02:33 PM:

Paul,

Just to make sure I understand, the fabric that you attained from Joanne's fabrics acts as the masking panel itself. It does not attach to anything, but attaches to the curtains rod and stacks to the sides like a drape when unmasking to 2.35? How does it handle stacking?

Thank you for your help! I am just about ready to finish placing my orders for all the material! Unfortunately I will not have any drapes yet, but being able to switch between ratios will be great enough for me for the time being!

[ June 04, 2016, 03:48 PM: Message edited by: Evan Samaras ]

Posted by Paul Adsett (Member # 25) on June 04, 2016, 05:17 PM:

1. The masking panels and the curtains are mounted separately on two different curtain traks. Masking panels are right in front of the screen, as close as you can get. Curtain tracks are about 5 inches out from the masking track. Masking panels and curtains are powered independently by their own motor and controller.

2. The curtains are standard 84 ins long curtains.

3. The masking panels are open rectangular wooden frames covered with matt black cloth. Thus very light and easy on the support rod and motor. The masking panel is thus a rigid rectangular panel and you need to allow enough extra curtain rod length on either side of the 2.35 screen for it to hide in. My masking panel is 18 inches wide, on either side. The drapes are necessary so that you do not expose unused area of the screen in the 4:3 and 16:9 positions.

4. Using the hand held remote you can run the curtains and masking, so they travel together.

Posted by Evan Samaras (Member # 5070) on June 04, 2016, 05:48 PM:

Thank you for clarifying for me Paul, now that makes sense. From scope down to 4:3 will require 4ft of masking, hence the 2 ft of masking on each side. Thank you again for help! By the way, I forgot to mention that your setup looks great!

Posted by Ken Finch (Member # 2768) on June 05, 2016, 01:39 PM:

Hi Evan. I have adjustable masking in my home cinema which has been in use now for over 14 years. The cinema is actually a 24ftx12ft cedarwood chalet. It is a mini replica of a i930s cinema complete with proscenium coloured screen lighting, and 2 sets of curtains. The scope screen is 9ft 6in. wide and is painted on the back wall of the insulated building with Dulux Brilliant white paint. The curtains and masking run on corded curtain track driven by 12volt car starter motors, obtained from a scrap yard. They are powered via an old battery charger! The actual masks are stripe of black painted hardboard about 7 inches wide. The curtains can be closed and stopped at any point
so that the outer edges of the screen are not seen. The various positions of the masking and curtains are controlled from a switch box and push buttons from the "box" end of the cinema. The circuitry includes "push to break" switches on the curtain tracks and mini solenoids on the motor boards. It all works quite well most of the time besides being so "heath robinson" I found the circuitry in a model engineering magazine to automate the movement of a a lathe cutting tool!! It is quite amazing what you can do if you look in the right places!! Ken Finch.

Posted by Ken Finch (Member # 2768) on June 09, 2016, 04:52 PM:

Hi, I had a "senior moment" with my posting on this topic. I should have stated "windscreen wiper motors" NOT "starter Motors". Ken Finch. [Roll Eyes]

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