Film-Tech Forum ARCHIVE: Lenticular Silver Screen Does it Reduce Hot Spots?

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Posted by Frank Angel (Member # 248) on 12-18-2005, 08:17 AM:

We are going to put in a new screen in a 400 seat theatre. The seating is arranged so that the isles are no wider than the right and left edges of the screen.

I know that high-gain silver screens have big problems with off-axis seats getting hot spots, and normally there would not be any reason to spec a high gain screen because light levels on the existing matte white are fine. BUT, they are hot on doing dual projector polarized 3D, so a silver screen is mandatory.

My understanding is that lenticular screens reduce the hot-spots and still allow for polarized 3D. Used to be that until recently you lenticular silver screens were no longer manufactured. But now there is a lenticular screen manufactured by MDR (not sure if that's exactly the right name....I am not at the theatre office).

Questions is, would it be wise to spec a lenticular silver screen for use with standard 2D films (the majority of what will be shown in this venue). I wouldn't be too concerned because of the unusually narrow seat arrangement, but I would be happy to hear from anyone who has actually seen a silver screen used for regular movies as to the pros and con, and if anyone has seen one of these lenticular jobs, that would be even more to the point.

Posted by Richard Hamilton (Member # 321) on 12-18-2005, 09:28 AM:

Frank,
It is probably MDI out of Canada. You could talk to Andrew Lee, he has posted on here a few times. I did a big screen 8/70 3d that also shows 35mm. I didn't notice any hotspots during the screenings of the 35mm presentation. The only bitch is focusing the lamp, because from the booth, the middle of the screen looks hot. I ended up watching the light on the dusty porthole to do the lamp focusing [Smile]

.

Later, Rick

Posted by Gordon McLeod (Member # 33) on 12-18-2005, 09:32 AM:

I didn't think anyone made a perforated lenticular any more
I would be interested in how it works out
on silver screens I always use the PSA since the hot spot visable from the booth is usually opposite to what the audience sees

Posted by Louis Bornwasser (Member # 3063) on 12-18-2005, 09:43 AM:

The silver screen will always hot spot.

The question is: in their zeal to do 3D; can they accept a reduction (maybe large, maybe small) in the overall quality of all other films?

Certainly not to be an improvement.

Louis

Posted by Mark Gulbrandsen (Member # 72) on 12-18-2005, 12:34 PM:

Technikote(or Technicrap) made the last true lenticular screen. There may be a foreign manufacturer that makes one but I am not aware of one. The original D-150 screens were lenticuluar but the lenticles varied in size across the width of the screen to improve light diistribution and decrease cross reflection. Harkness has the best equivelent in my experience..... Stewart is not sturdy enough but not sure if they have something close or not anyway..... Hurley has gotten an F on the last couple of screen jobs we did with them.... Lets see if others chime in as to what brand they find works best.

Mark

Posted by Richard Fowler (Member # 893) on 12-18-2005, 01:21 PM:

Tecknikote and Hurley are the only people handling lenticular on a special order basis....we rescreened a D150 house ten years ago and the lenticular was a pain due to the heavy weight of the fabric backing to the screen surface. Andrew Lee is no longer at MDI and the last report has switched over to Franklin Designs.

Posted by Richard Hamilton (Member # 321) on 12-18-2005, 01:55 PM:

quote: Richard Fowler
Andrew Lee is no longer at MDI and the last report has switched over to Franklin Designs.

My bad. Bobby told me this but I forgot [Embarrassed]

Posted by Mark Gulbrandsen (Member # 72) on 12-18-2005, 08:12 PM:

quote: Richard Fowler
Tecknikote and Hurley are the only people handling lenticular on a special order basis....

Richard,

I'm not sure that even Technicote can supply lenticlular any longer. It was about the same time frame... 10 years ago that I talked to them about producing a large Leticular surface for a customers plan for a deep curve screen. I was told back then that they had barely enough to produce the screen I wanted and that after that material was depleted there were no plans to have more produced.... because of lack of orders. 10 years ago theirs was the only really true lenticular surface left on the market. Back then Hurley could not produce one for me at all.

Mark

Posted by Lyle Romer (Member # 1266) on 12-18-2005, 10:10 PM:

Forgive my ignorance but what is a lenticular screen?

Posted by William Hooper (Member # 71) on 12-19-2005, 03:34 AM:

A matte screen throws diffuse reflections, straight back, up, down, left, right, like the splat when you throw a rock in a puddle.

A lenticular screen is designed to minimize off-axis reflictions, thus reflecting light more straight back (but keeping up & down reflections, since the audience is seated below the centerline of the screen). It is usually done by manufactuing the screen with vertical structures like ridges on its surface.

If you're lucky, John Pytlak will add more that will clarify this, & possibly include the extra treat of the word 'specular'.

Posted by Frank Angel (Member # 248) on 12-19-2005, 07:34 AM:

quote: Louis Bornwasser
The silver screen will always hot spot.

The question is: in their zeal to do 3D; can they accept a reduction (maybe large, maybe small) in the overall quality of all other films?

Certainly not to be an improvement.

Well, they really are hot to do dual 3D, but I know the downside here and that's why I want to investigate lenticular. I have no direct experience with this and only know from reading and hearsay that lenticular reduces the hot-spot problem to a minimum. Evidently part of the original CinemaScope package spec-ed a lenticular silver screen, I think Fox dubbed it their Miracle Mirror surface or something like that. Supposedly it eliminated hot spots except for extreme off-axis seats. And of course the helpful thing here is that there are no off-axis seats in this room. I am hoping with the combination of that and whatever attenuation lenticular will give in terms of hot-spots, I can get away with one-screen fits all.

I guess the safest path would be to install a normal flat or medium gain (they do slide presentations and 16mm so some gain is very helpful) and then if they want to do 3D, just hang a silver on the same frame (match the perfs? [Eek!]

). But if we could get a lenticular that will work for both 2D & 3D, it would be really nice. I also love the idea of being able to show 2D shorts and attractions, then switch to 3D in one shot.

First hurdle I guess is finding a manufacturer, although I am almost sure MDI claimed their silver screen was lenticular. Now if only I could get them to lend me one to try out first. Yea right.

[ 12-21-2005, 04:12 AM: Message edited by: Frank Angel ]

Posted by Mark Gulbrandsen (Member # 72) on 12-19-2005, 08:36 AM:

Since you're near Brooklyn (I think) why not go over and see what Technikote has to offer since thats where they're at....... Also the LF silver screen from MDI at Thanksgiving Point is a sprayed screen.... definately not lenticuluar. Most manufacturers will send you a screen surface sample at N\C but you first need to know exactly what a real lenticuluar surface is... so Technikote may be good place to start. If they don't have any large quantities left they might still have a sample swatch of it.

Mark

Posted by Richard Hamilton (Member # 321) on 12-19-2005, 08:40 AM:

Frank, Call Franklin Designs at 1-800-467-0641 and ask for Dianne. I just talked to her and she can give you some input. If she doesn't know, she can get you in touch with the screen manufacturers.

Hope this helps, Rick

Posted by John Pytlak (Member # 331) on 12-19-2005, 09:51 AM:

You need to be very careful when using a lenticular screen with any fixed pixel array digital projection system --- very easy to get into moire pattern problems as the pixel pattern interacts with the vertical ridges of the lenticular screen.

Screen definitions:

http://www.answers.com/topic/silver-screen

quote:
Excellent for use with low-wattage projectors and the early projected monochromatic images, the silver screen, or silver lenticular (vertically ridged) screen, however, provides narrower horizontal/vertical viewing angles in comparison to its more modern counterparts and tends to color-shift to blue when color images are used, in addition to hot-spotting (the tendency of single source projection to over saturate the screen's center, leaving the peripheries darker). Due to these limitations and the continued innovation of screen materials, the manufacture of silver projection screens was generally phased out, though never fully discontinued, while the term "silver screen" itself continues to be used to refer to projection screens in general and motion picture projection screens in particular.

http://www.projectionscreens.com.au/screen_materials.htm

quote:
Silver/Silver lenticular screens also provide a higher gain, however these screens will cause a colour shift to blue, have a smaller viewing angle and can hot spot. These screens are great for old black and white, low power projectors but not suitable for contemporary projectors. However, this material is still the best medium for 3D projection.

Posted by Frank Angel (Member # 248) on 12-20-2005, 05:27 AM:

Thanks guys. This is going to be interesting. I am encouraged by the only time I saw a theatre with a silver screen used for standard 2D was in Kingston NY. We weren't there to see the movie, but to talk to the owner. I was very impressed with the unusually bright image. When I was given a tour of the booth, I asked the projectionist what size xenons were being used given how bright the picture was. It was what I would guess a 30ft width screen. When he told me 1600W, I almost fell over. I asked how that was possible, and he answered they had a silver screen. When I heard that, I looked at it more carefully and was very surprised to see no hot spotting, even as I walked the width of the theatre. And here again, the trick seems to be that the seat rows were much like my theatre, not wider than the screen. If I can get a silver screen to look that good, I would be very happy. We even might have to use those diaphram rings in the projector lenses to drop down the light or defocus the lamps.

Posted by Mitchell Dvoskin (Member # 751) on 12-20-2005, 08:38 AM:

The Lafayette Theatre in Suffern, NY has a 30' wide silver screen, and I have never seen a hot spot.

Posted by John Pytlak (Member # 331) on 12-20-2005, 08:47 AM:

Again, a silver screen acts almost like a mirror, so ideally ray tracing should be done to properly curve it to reflect the projector's light evenly back to the center of the audience. In a relatively narrow theatre (seating area not much wider than the screen), proper screen curve and tilt can usually achieve reasonable light distribution. But wide seating areas are likely to have uniformity issues, especially in the seats closer to the screen that are away from the centerline of the theatre.

Posted by Frank Angel (Member # 248) on 12-21-2005, 04:11 AM:

quote: John Pytlak
You need to be very careful when using a lenticular screen with any fixed pixel array digital projection system --- very easy to get into moire pattern problems as the pixel pattern interacts with the vertical ridges of the lenticular screen.

Digital? We don't have no stinkin digital! [Big Grin]

And Mitchell, I guess it's about time I took a trip out to Suffern to have a look-see.

Posted by Andrew Lee (Member # 1330) on 12-21-2005, 09:59 AM:

Hi All,

I'm baaaack!

As most of you know, I am no longer at MDI. I am now with Franklin Designs. I would love to chat about any aspects of 3D presentation and/or screens and could do so for days on end. Unfortunately I am in a position whereby I can't say anything that relates directly to a company's particular product.

Otherwise I would be most happy to help out with general questions and concerns as they relate to 3D or screen issues. Feel free to e-mail me directly as I don't go to this site as often as I used to. I hope all of you are well and have a very Merry Christmas.

Cheers,

Andrew

Posted by Frank Angel (Member # 248) on 07-02-2006, 11:13 AM:

OK, here's the updated poop. They installed a silver screen at the museum. The woman who was gunghoe about running 3D in this venue, convinced the powers that be, after considering my caution about the possibilities of hot-spots, to go with a silver screen. Screen is now installed; she got another job and left. Unless I can whip up the same enthusiasm I did in her, we may never run a 3D movie in that theatre.

As for the specifics of the real-world use of the silver screen -- I ran my first film and video on the new screen there last night and I must say, I walked all over the theatre, top to bottom, side to side - no descernable hot spotting -- none. I will test it with a light meter as soon as I get the chance, but at least with a picture running, if there is any variance in light, I can't see any and I am sure the average moviegoer sees a perfectly acceptable. The fact that the seating area pretty much is only a few feet wider than the width of the screen and the height of the booth puts the projectors on a very slight angle to the screen, seems to make it an ideal configuration for a silver screen to serve dual purposes of standard and 3D presentation.

That said, the advantage in terms of increasing the brightness of the image is remarkable. I may even have to have cut back the 35mm lamphouse amps or perhaps even go to a smaller wattage bulb. Color saturation is demonstrably improved. As for the improvement in the video projection, well, that's day and night. I would almost bet the video projector will easily reach 16fL and if not, it will be damn close. Video image, except for all that is bad about video images, at least looks as bright as 35mm presentation. It also will bring 16mm up to snuff as well.

Because we switch from one format to another, sometimes back-to- back in the same program, at the very least I will be able to match screen brightness across them all. To bad silverized screens don't work in more situations.

I pitty all those venues that are going to be expected to show 3D when the 2D into 3D craze takes hold, as Lucas, Speilberg et al seem to be salivating over. How much you want to bet most of the theatres will not have the advantage that I lucked in on and they will wind up being stuck using the silver screen for their 2D presentations as well, and then suffering with all its very real disadvantages when used in the wrong configuration.

BTW, MDI claims they are perfecting a new silverizing technology that does NOT produce hot-spots if seating is kept within certain perameters; they are still restrictive to width of seating area and angle of the projectors, but it is claimed that they are significantly broader than other manufacturers' silver screens.

Posted by Louis Bornwasser (Member # 3063) on 07-02-2006, 01:56 PM:

Frank: your theatre was actually engineered. prob. a real architect....most are cookie cuttered with an architect that may have lots of cinemas, but no real idea of what he is doing. My short hand for these guys is "lobby artist." Rarely are the auditoriums proportioned correctly or well; usually just boxes.

The silver screen problems just disappear when the angles are correctly calculated; yours must be right. Louis

Posted by Stephen Furley (Member # 1277) on 07-02-2006, 04:31 PM:

quote: Mitchell Dvoskin
The Lafayette Theatre in Suffern, NY has a 30' wide silver screen, and I have never seen a hot spot.

Neither have I; I've seen for or five films there, and the first time I din't realise that it was a silver screen. This is in stark contrast to many other places where I've seen them.

quote: John Pytlak
In a relatively narrow theatre (seating area not much wider than the screen)

This is the case at the Lafayette. I normally sit towards the front of the rear section of the auditorium, close to the axis, and about two-thirds of the way back.

Frank: do go and see the Lafayette; it's worth a visit. Mention my name to Peter Apruzzese, and he'll probably have you thrown out. Only joking! It's in New York, but only just; a few hundred metres to the South is the border with New Jersey. The classic film shows are on Saturday mornings, and, depending on the date, it's sometimes possible to see one of these, and then catch an afternoon or evening show at the Loew's Jersey.

The Lafayette does run 3-D shows from time to time, but I've never seen one there.

Posted by Bernard Tonks (Member # 809) on 07-06-2006, 09:35 AM:

When I saw a demonstration of digital “Chicken Little 3D" on a MDI screen, the gain was 2.8, compared with about 1.8 for a normal Perlux screen (source Cinema Technology). I never noticed any hot spot or fall-off on a picture size of at least 35 feet in a fairly large auditorium.

Posted by Richard Fowler (Member # 893) on 07-06-2006, 10:58 AM:

I saw Chicken Little in a stadium house of which the brightness varied greatly from top to botom of room and less so from side to side. screen frame was curved but not angled upward toward the audience per SMPTE specs...so some people had a great show and many a fair show. MDI screens vary in gain quality and spray pattern issues to the point I can walk in room that they are installed and I know what is on the frame

Posted by Mark Gulbrandsen (Member # 72) on 07-06-2006, 11:11 PM:

I agree Richard, This can be actually be seen on the USL light meter at the 15/70 CDC system at Thanksgiving Point. I don't think MDI is doing as finely controled a spray job as Harkness does.

Mark