Motorised top masking for a Curved Screen? (1 Viewer)

[murrayThompson]

I was a cinema projectionist for over 35+ years and worked in many theatres that had motorised top black masking that were on curved screens. These theatres were usually 70MM and that masking went up for 70MM. Its rather difficult to make movable top masking thats curved, especially in a smaller room where everything is quite close, unlike a real cinema.


I have a curved microperf Stewart ST130 150" scope screen with fixed top and bottom masking and motorised sides setup for 4.3, 1.66, 1.75, 1.85 and scope. I have always wanted to have movable top masking for when I screen 70MM films so the change looks dramatic as it did in the cinema. Has anyone here ever made motorised top masking on a curved screen? Its real easy for a flat screen but harder for curved....

The only way I know of is to have a long metal pole with a curve the same as the screen. The top masking has a pocket in the bottom to hold the curved pole, on the back of the fabric one uses festoon curtain tape with rings and cords to raise the fabric. There is quite a lot of work to do this nicely and motorised with a stop.

My question is has anyone done this a different way for a curved screen and motorised? I would love to know....

 

[nanook]

I'm trying to remember just exactly how it was done in the world of professional theatrical draperies. Obviously, depending on the amount of curvature, it will naturally force the 'backside of the curve' downward. I have to assume the curved pipe was rigged overhead from multiple loft blocks, laid out in a curved pattern mimicking the desired curvature of the pipe and screen. Perhaps as few as three hanging points would do the trick for a 150"-wide screen. And you'd have to run the linesets over to a head block and then down-? to the motor. As you point out, fitting that sort of hardware above your screen 'assembly' may be very tricky, as space may be at a premium. I've never done it myself, and am not being particularly helpful, here - I'm sorry. But I would have to think something along these lines would be needed to produce both repeatable and reliable operation.

(The real fun job is designing movable bottom masking for screens in the 40-60 foot-wide range, and have that operate repeatably and reliably - and being perfectly level. I've seen it done in a couple of venues, and it is a thing of mechanical beauty).

 

[murrayThompson]

Im sure I could make it happen, but would love input from others!

 

[DFurr]

One of the theatres we operated in the mid 90's seated over 400 and had a huge curved screen. It was a constant height screen so the side masking was no problem. The problem IMO was I was never happy with the focus on 2:35:1 pictures. I upgraded the lens but the problem didn't go away. The center could be razor sharp but the sides were soft. Most people didn't even notice it but It drove me crazy until we sold the theatre. It was someone else's problem then!!

 

[Frankie_A]

Ah Murray, a man after my own heart. I too have worked in the movie business (exhibition) since I was 19yrs, and was 13 when they installed CinemaScope, so I too know that fondness for a curved screen. The original CInemaScope spec specified a curved screen as Zanuck at Fox was determined to get the same effect as Cinerama which, at the time was a huge success. CInemaScope was the poor man's Cinerama. Like Cinerama, it had a very wide screen compared to what the world had heretofore been watching movies on (essentially a square screen), it had a curve like Cinerama and it had multichannel stereo too (albeit 4 track rather than 6). For all intents and purposes, it was a spectacular revolution in the way the world would watch movies. The square "Academy" aspect ratio was gone forever. Even films that were shot and in the can in the 4.3 Academy Ratio were shown wide by cropping. SHANE, for example was shot 4.3, but Paramount would rather suffer some copping rather than present it square and no theatre owner who just spent a lot of money to put in a wide 2.356:1 CinemaScope screen was about to show a square movie on it sitting in the middle of the massive expanse of a screen.

And of course, we both know that most theatres back then had CURTAINS! If the reader doesn't know what I am talking about, I applaud your youth, but lament what you missed during the Golden Age of the Movie Palaces. That's when presentation had class. That's when every theatre was unique and had it;s own character and did not look like utilitarian, cookie-cutter, assembly-line, soul-less affairs that will suck the life out of your spirit just walking into one. Even the lowly neighborhood theatres and the Mom and Pop theatre used curtain. The Management Operations Manual in a theatre I worked in in Austin TX had a whole section on "Curtain Protocol." I will always remember the one admonition -- it was like one of the ten commandments -- "The audience must NEVER come into the theatre and see an NAKED SCREEN!" And they were not kidding. It was widely held my the staff that people had been fired for just such an infraction.

So I know what you are looking to do, I know what hardware you are looking for. AND I HAVE such a beast -- a curved curtain track. I have been using it since the 80s when I built a home theatre using an Advent Videobeam as the center piece, then putting masking around it and finally I found this curtain track that could be manually bent. Here is a picture of the track. It was ordinary traverse track that I found in a local hardware store, made of aluminum like standard traverse tracks just like my mom had on every window with cords on the side. Curtains would split from the middle. The only difference with this track and all the other household tracks was that as you can see, the track has multitude cuts in the 2 in width the track that allows you to literally bend it any way you want.

Sorry for the bad focus, but you can see the slits that allow the track to bend. I attached a bicycle chain to in place of the cords and that around a TombThumb curtain track motor. Here you see the curve is very severe on the end of the track, basically needing to pull most of the curtain material toward the wall, but the center of the track was also curved only not as much.

This is what it looked like with the Videobeam and the surround masking.

This was to show the 3DTV system classes, so you don't get a good sense of the curve, but this one is better:

Please ignore the hand & shutter glasses in the picture -- it was to show the components of 3D system (by a company 3DTV) that allowed us to show quite a number of 3D titles way back in the 80s. Shutter glasses with alternating video on SVHS tapes were the way it worked and it worked very well. But the point of this picture is so you can see the obvious curve in the track.

You should be able to adapt masking as well as curtains with this kind of track if it exists anywhere. But, all that said, there is a sad caveat in all this: the sorry fact is that I have been looking to get another one of these tracks for over 15 years with no luck. Since HD has come upon us, I had to put the Videobeam and the screen out to pasture and we also need a new curved track. But I can't find that curved track anywhere. Sure you can get curved theatrical tracks (and I even looked into that, but they are MUCH bigger and they weight a lot more....a LOT more than the track I was using, not to mention a lot more expensive.

I do have to warn you, Murray, while this or any other similar curved track may be good for curtains and/or masking that moves vertically, spitting left to right, rigging top and bottom masking to move up and down in unison is a much trickier task, believe me. I worked in a theatre that had top/bottom masking and the rigging involved a complicated system of pulleys and cables because vertical curtain splits and masking splitting left/right only requires two cables and a pulley on each end. With moving a top and bottom mask up and down, the trick is that you need to move all four points of both the top and bottom masks at exactly the same time and same amount to keep the masking level -- I've seen one in operation and it was fraught with operational issues and lots of downtime. I was finally abandoned and they opted for changing between 70mm and 35mm just by changing the width alone and keeping constant height. Unfortunately and as you pointed out, that diminishes the drama between the two formats.

So if anyone knows of where we can find a curved track let us know. And of course, the ideal would be one that was lightweight and if the stars were aligned correctly, one that is motorized as well!

 

[murrayThompson]

So if anyone knows of where we can find a curved track let us know. And of course, the ideal would be one that was lightweight and if the stars were aligned correctly, one that is motorized as well!

I already have a curved motorised curved side masking and main curtain which is not only curved to match the curved screen but the track curves on the ends at 90 degs and the curtain then hides in side wall pockets. I have a German system and the tracks we bent by the supplier to match the curve of my screen.

Its not curved tracks Im after its motorised top masking to raise up for the 70MM films. I know it can be done with cords and rings sown into the bacl of the velvet but its still very complex to do. Lets say involved.

You can see my tracks and curtains in my HT build. https://www.blu-ray.com/community/gallery.php?member=RapalloAV

 

[Frankie_A]

Wow, Murray -- my mouth is watering. I am blown-away by that incredible beauty and style of your theatre. You are aware that it has my class than most of those multiplex dark, dank, black holes-in-the- wall And we certainly are on the same page with the idea that cinemas today still put surround speakers visible on the side walls. I can understand back in the 50s when stereo with surround was a new and add-on system, it was expedient to just hang speakers where they could, but to keep doing it that way was just architecturally sloppy and unimaginative. There was no reason why once new builds were being made, that surrounds could not be designed to be mounted within the walls, so they are as invisible as are the screen speakers, Internally mounted speakers not only are aesthetically pleasing (clean lines) but any acoustician will tell you, it is better to have speakers mounted flush with the wall where they propagate the soundwave, as you have wisely done, with your screen speakers.

Oh yah, I love the curtain lighting on dimmers and the ability to change hues is a terrific plus.