Film-Tech Forum ARCHIVE: The junk called IMAX with Lasers

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Posted by Marcel Birgelen (Member # 6801) on 05-13-2017, 08:18 PM:

I finally had the opportunity to visit an IMAX theater upgraded with their dual-laser projection system and I must say, it was a pretty significant letdown.

I went to see the late night show of Alien: Covenant at the recently reopened IMAX theater in Kinepolis Brussels. It was closed from 2005 until 2016 and before 2016 it didn’t show feature films. It also never got an IMAX 3D upgrade. According to marketing back then, it was the second biggest IMAX screen in the world and according to the marketing now, it’s the largest in Europe. Exactly where it ranks isn’t really that important, but it’s indeed pretty damn huge.

The theater is a traditional 70mm IMAX location, built pretty much according to IMAX specifications. During the recent refurbishment, new seats were installed, the walls got some treatments, a new silver screen was installed and the theater also got the 12 channel IMAX sound system. At the heart of the refurbishment obviously were the new laser projectors. I’m not sure if they also retained their original 70mm projector and if they did, in what shape it is.

Unfortunately, the visit already started on the wrong foot, when I went to the bathroom and they demanded 40 cents for the privilege and my 50 euros were no good, because they didn’t have sufficient amount of change. Yeah, sorry, that’s what the ATM gave me. When I told them I really had to use the bathroom, one of the cleaning ladies actually blocked the entry. I passed her by and went anyway. How can you deny a paying customer bathroom services? What are you thinking? I was greeted by security afterwards, I told them to call the police and tell them they deny people entry to their toilet facilities, which they’re legally required to provide. Maybe they have a right to ask a fee for it, which I think is in itself already customer hostile, but then they also need to be prepared to accept all money considered to be legal tender or provide other means of payment. It ended in two figures barking insults at me, I decided to simply walk away and ignore them. The whole situation was actually quite comical, since it was a whole lot of theater about nothing and I would not let them ruin my evening.

What was more of an impact was the actual presentation, because it was a ton of shit. If this is the kind of quality IMAX believes can replace proper 70mm projection, please count me out.
But let’s start with the sound first. I’m totally aware it’s quite difficult to get sound right in such a large and especially high auditorium. Still, compared to what better Atmos and 7.1 rooms can achieve, this was especially dull and flat. The presentation totally lacked any form of bass. There was no dynamic in the sound and it lacked the punch necessary to leave an impression.

While the sound wasn’t great, it was sufficiently good overall to avoid annoyances. What was annoying was the overall picture quality. I’d say I’ve never seen a picture as bad as this in any digital projection in all those years:

- Laser speckle all over the place. So dramatically visible, it’s like someone threw a bunch of pearlescent beads all over the screen.
- IMAX with Laser uses anamorphic lenses to squeeze the image fill the screen. This results in non-square pixels. Even though the image is supposed to be in 4K, you WILL still see pixels at those screen sizes. The image looks a lot like that on an Apple Lisa, probably one of the few computers in history that featured non-square pixels...
- The non-square pixels result in the necessity to rescale practically all content and it shows. You get FAT and UGLY scaling artifacts EVERYWHERE.
The whole experience is a lot like looking full-screen at an 11-year old YouTube video on a large 4K monitor while pressing your head against it.

So, this is the technology which, according to IMAX (the company), is ready to replace 70mm on GIANT screens? You must be f*cking kidding me. This is just another hack job, to be honest, I even prefer the look of the Digital IMAX with Xenon.

Posted by Carsten Kurz (Member # 5396) on 05-13-2017, 09:22 PM:

I haven't seen the heavy rescaling artifacts you describe, but the speckle visible on those silver screens is indeed horrendous. Why the hell do they actually still need silver screens with the twin laser installations and color separation 3D?

Your loo story is absurd. They should be ashamed.

- Carsten

Posted by Marcel Birgelen (Member # 6801) on 05-14-2017, 03:27 AM:

The new Alien movie is in 2D, but as far as I know, the 3D system uses 3D glasses based on the Infitec/Dolby 3D color seperation technology.

Polarization filters in combination with laser sources seem to be highly inefficient.

Still, they seem to use high-gain silver screens. Maybe because of backward compatibility or because they still need the gain given the size of the screen.

The speckle might be a Barco problem? I have no hands-on experience with any Barco laser projector so it's hard to tell, but AFAIK IMAX uses a modified Barco laser projector setup. The Dolby Cinema Christie dual laser setup barely shows any speckle at all though.

I'm not sure if there were technical problems, but there was a massive amount of aliasing going on. Not only during the movie itself, but also during the IMAX feature trailers, which should be specifically tailored to this system.

Maybe there also were some alignment errors between the two projectors, which could explain the general blurriness of the image.

Compared to Dolby Cinema, this is really a loser on all fronts in my opinion. While Dolby Cinema usually employs smaller screens, they are more fit for your average movie presentation. The image also has more contrast, more brightness and the lack of the necessity of scaling to strange, non-integer proportions ensures an artifact-free image.

I've experienced the 12-channel IMAX sound system at two locations now. It's probably not sufficient experience for a definitive conclusion, but I think a properly configured 7.1 room already outperforms this system in overall quality. Compared to a properly implemented Dolby Cinema setup, it really is no comparison at all.

So, nothing positive? Well, first off all let's give them kudos for reopening this long closed location, which obviously wasn't cheap. Also, let's give them kudos for actually running movie-based themed music in the IMAX lobby.

Now, do us all a favor and get a working film setup, so you can show those movies that are still released in this format the way they're supposed to be seen.

Posted by Mike Schulz (Member # 4297) on 05-14-2017, 05:27 AM:

They must have done something majorly wrong with their setup or installation at that theatre. The IMAX laser presentations I've seen at the Chinese Theatre and the Universal Theatre here in Los Angeles were rock solid. The speckle was barely present so I'm almost positive that is not a Barco technology issue. Maybe they didn't put shakers on the screen or something that helps to eliminate that issue. As for the sound, I can agree with you on that. Even the new 12.0 system they are using doesn't hold a candle to a good Atmos setup. Then again, IMAX sound has always been inferior to everything else out there.

While I think the new IMAX laser presentation is a huge step up from the Xenon setup they were using before, it's still not as good as Dolby Vision. I've gotten in many arguments defending my position and I might be slightly bias since I work at a DV venue, but I can still see the flaws with IMAX laser and with Dolby Vision it is a damn near perfect picture every time.

Posted by Carsten Kurz (Member # 5396) on 05-14-2017, 07:05 AM:

Mike - do you know wether these two locations still use silver screens? I understand they may leave an existing screen in place until it is replaced regularly. But I know one location in germany that had a silver screen when they installed laser-Imax, and received a new silver screen AFTER the system had been operating for a while. The speckle on these silver screens is highly annoying. This speckle alone is the reason I won't visit a laser IMAX theatre again. It's hilarious to attempt to improve major aspects of the audiovisual presentation and then ignore such a major flaw.

I have seen 'standard' Barco Laser presentations locally, and they don't suffer from that issue. While the IMAX laser systems have been built by Barco, I don't know wether they employ the same speckle reduction. The light engines are very different between standard Barco lasers and IMAX lasers.

- Carsten

Posted by Mike Schulz (Member # 4297) on 05-14-2017, 12:15 PM:

Casten - I'm not 100% sure but I believe both sites have the silver screens and they use shakers to help eliminate the speckling problem. I will say that when I first saw "Furious 7" at the Chinese Theatre, I did notice some hot-spotting and minor speckling happening (everyone else I was with claimed I was taking crazy pills, however) but ever since then when I've gone back, I haven't noticed either of those issues so I think they have worked some more kinks out since their first installations.

At the Universal Theatre, I saw "Batman vs. Superman" which was probably the best showcase of the laser technology as it had a lot of 15/70 scenes that filled the whole screen and I was actually quite shocked by how good it looked. In my opinion, Universal is the better venue to see the laser presentations as it is a proper dimensioned real IMAX theatre and the sound is way better there, too.

If I were to take a guess as to why Marcel's theatre looked so bad, I would guess that they hadn't installed the screen shakers yet since the symptoms were hot-spotting and noticeable speckling which is what the shakers eliminate.

Posted by Dave Macaulay (Member # 813) on 05-14-2017, 12:49 PM:

The shakers can't eliminate hotspot but do get rid of speckling. The speckling is quite bad if the shakers are not working. Sometimes that system does fail.
Yes the pixels are slightly rectangular but so what? There's no magic in square pixels.
They are not Barco laser projectors but many components are produced by Barco. The light engine is very different from the Barco laser projector models.
Dolby Vision® is definitely impressive in a properly designed cinema. The extended contrast is usually wasted because of exit aisle lighting to meet local rules... or because someone stumbled and the manager turned the aisle lights up.
The Imax laser system has considerably better contrast than a normal xenon DLP digital cinema projector. Imax tries to keep interior lighting minimal but local codes have to be followed.
Sound quality is subjective, Imax sound is at least consistent as the system runs daily self-checks on all channels to confirm levels and that there are no blown drivers or failed amps. That usually takes a patron's complaint in standard cinemas.
Overall I find Imax laser to be very impressive. Much better than the standard 2K DLP stadium cinemas. Worth the upcharge? For some movies yes.

Posted by Marcel Birgelen (Member # 6801) on 05-14-2017, 05:48 PM:

Hotspotting wasn't really the issue here, we were watching a scope feature on a 1.43 screen, so hotspotting would only be visible in the left and right edges if it would be a problem. Which actually negates the whole idea of such a giant screen, because the effective screen size isn't much bigger than that of a larger, normal auditorium.

For those interrested, they made a small making-of video about the refurbishment.

I'm still wondering, where the screen shakers are placed, if they're present at all and if they work similarly as described in the Dolby patents. If you look at the video, you see there are a bunch of speaker-alike looking cylindrical devices mounted in the frame, are those the screen shakers being used by IMAX? If so, it seems to be an ultrasonic system.

Apparently, Dolby uses screen shakers in their Dolby Cinema venues, although everybody I asked has been a bit sketchy about them, it's like they're some kind of big trade secret. Maybe someone here can shed a light on them, if they're actually being used.

quote: Dave Macaulay
Yes the pixels are slightly rectangular but so what? There's no magic in square pixels.

No, there's indeed no real magic in square pixels, but I guess we've gotten used to them and therefore our brain will more easily "discard" them, if they're visible.

And yes, they are pretty much visible all the time. Also, the ever-present subtitles in both French and Dutch didn't help to make them less visible.

For some reason, my mind was constant telling me: The picture looks vertically stretched. It almost told me to try to find the button to resize it to the proper proportions to make it look "right". Maybe it's a "me" problem, but I really think our mind has been trained, over the years, to accept square pixels as a normal fact of life. So, non-square pixels just look odd, just like a Apple Lisa looks odd, if you happen to find a working model somewhere.

Posted by Dave Macaulay (Member # 813) on 05-14-2017, 07:05 PM:

Yes those cylinders are the screen shaker. I don't know if the system is a "trade secret" - and I'm not going to find out by describing it.

Posted by Carsten Kurz (Member # 5396) on 05-14-2017, 07:59 PM:

Screen shakers are not a trade secret, but projector manufacturers prefer to hide their necessity - because it shows their inability to get rid of speckle on their side.

- Carsten

Posted by Bobby Henderson (Member # 840) on 05-15-2017, 12:10 AM:

Kind of a stupid question, but "screen shakers?" There's something literally shaking the screen to suppress the appearance of speckles? How does this work? This "shaking" taking place, is it rapid vibration or something? Wouldn't this shaking or vibration yield a dramatic, negative hit to image sharpness and resolution?

Posted by Marcel Birgelen (Member # 6801) on 05-15-2017, 02:01 AM:

Well, yes... they shake, vibrate, or how some call it, "massage" the screen.

There seems to be more than one way to do it, one is via mechanical contact to the screen assembly itself and another is via ultrasonic actuation. To me, it looks like that's what IMAX is using.

There might be other implementations, like electromagnetic or even electrostatic actuation. I've seen electromagnetic actuation mentioned in patents, but it wasn't further explained in the ones I read.

The vibrations should not be visible to the naked eye and therefore should not create a noticeable impact on image focus as such.

The general idea is that by shaking the screen, you diffuse the high intensity spots created by laser interference and therefore reduce the visible speckle. In some of the patents, they also describe a special diffusing screen coating in combination with “screen shaking”. Essentially, you rough up the surface in a random fashion, combined with vibrating the screen, this should further eliminate visible speckle.

Since most IMAX locations seem to be using silver screens, the screen shaking itself seems a bit counter-intuitive to me. Since the silver coating on the screen is designed to be less diffusing than normal, white screens.

quote: Dave Macaulay
Yes those cylinders are the screen shaker. I don't know if the system is a "trade secret" - and I'm not going to find out by describing it.

Thanks for pointing out they are the screen shakers.

I'm not sure if you're willing to tell, but I guess they don't actually contact the screen?

Posted by Carsten Kurz (Member # 5396) on 05-15-2017, 04:26 AM:

http://www.google.com/patents/US20130010356

As far as I know, every RGB (3p/6p) laser installation uses screen shakers. The cheaper phosphor conversion lasers do not suffer that much from speckle, so they don't need it.

I'm wondering why they don't use them in our few german laser IMAX installations. Maybe they are installed, but not in operation for some reason?

At the level IMAX is usually driving their audio system, you would think there is no need for dedicated screen shakers...

- Carsten

Posted by Marcel Birgelen (Member # 6801) on 05-15-2017, 07:27 AM:

As you can see in the Brussels installation and confirmed by Dave, they were actually installed.

Yet, there was still a massive amount of speckle visible. So either the result is still pretty meagre or they were simply not operational.

AFAIK there are three IMAX Laser locations in Germany. Berlin, Sinsheim and Karlsruhe. Maybe I'm missing one, but IMAX's presence in Europe always has been a bit of a hit and miss. Many locations closed before feature films became IMAX's new business model.

All of those locations were former 70 mm locations and at least two of them (Berlin and Sinsheim) were former 70 mm IMAX locations, pretty similar in layout to the one in Brussels and comparable screen sizes. I guess, it would be odd if none of them got the "shakers".

Posted by Geoff Jones (Member # 3668) on 05-15-2017, 07:48 AM:

I will readily admit that I barely understand what you guys are talking about, but it sounds asinine to me.

Your new technology looks like shit unless you physically shake or vibrate the screen? Does it get shaken evenly across the entire surface? What effect does shaking the screen have in the long run?

quote: Marcel Birgelen
The Dolby Cinema Christie dual laser setup barely shows any speckle at all though.

quote: Mike Schulz
The IMAX laser presentations I've seen at the Chinese Theatre and the Universal Theatre here in Los Angeles were rock solid. The speckle was barely present.

Is it really okay if there's just a little speckle? That sounds sorta like saying, "Oh, the film was barely scratched."

I haven't seen anything in 2k LieMax except for the Raiders of the Lost Ark re-issue several years ago, and the pixelation and low-res blurriness was terrible from the front third of the auditorium. It sounds like I don't need to bother with SpeckleMax.

Posted by Marcel Birgelen (Member # 6801) on 05-15-2017, 09:07 AM:

quote: Geoff Jones
Is it really okay if there's just a little speckle? That sounds sorta like saying, "Oh, the film was barely scratched."

The Dolby Cinema presentations I've seen, there was, in practically all scenes, no speckle visible at all. Only in extremely bright scenes and if you go looking for it, you will see a tiny bit of speckle is still in there. Most people will probably mistake it for noise if they notice it at all. Only when the camera pans you can identify it as speckle.

The IMAX presentation I've seen looked like a unicorn barfed all over the screen. Pearlescent glitter all around in any bright scene.

None of the current projection technologies is entirely artifact fee, but there's a difference between something you need to go looking for and something that screams in your face almost all the time.

quote: Geoff Jones
Your new technology looks like shit unless you physically shake or vibrate the screen? Does it get shaken evenly across the entire surface? What effect does shaking the screen have in the long run?

Good questions actually. I guess the idea would be to uniformly shake/vibrate the entire screen. What it does to a screen in the long run might also be interesting, especially if you're considering silver screens that do have a fragile, special coating on the surface.

Posted by Dave Macaulay (Member # 813) on 05-15-2017, 11:13 AM:

Laser speckle is created in your eye, it's interference patterns from the coherent light. Oddly, if you move your head side-to-side the speckle might move... one way (can't remember which) means you're nearsighted and the other way means farsighted, not moving means neither. I'm not sure if this is true, but it worked as described for me (nearsighted).
The shakers move the screen in and out a couple of mm in a random pattern: that changes the wavefront reaching your eye and, although the speckle is still there, it's also randomized and your brain filters it out.
Speckle is most visible with green laser light, less with red, hardly at all with blue.
Phosphor lasers use the blue laser light directly for blue - the speckle is pretty much unnoticeable - and hit a phosphor target with another blue laser which emits yellow light, that's split into red and green. The phosphor's yellow fluorescent light is not coherent, it's just like light bulb light, and it doesn't create any speckle. The phosphor is usually on a spinning disc to allow cooling - and the phosphor does wear out eventually.
"True" laser illuminated projectors all need to do speckle reduction somehow. I think there are some systems that use a complicated spinning disc "lens" between the laser and light engine but I haven't seen that.

Posted by Joe Redifer (Member # 3) on 05-15-2017, 04:49 PM:

Are they using nearest-neighbor scaling, thus resulting in non-uniform pixel sizes across the screen? Like, did they just buy a cheap HDMI scaler made in China off of Amazon? You'd think they'd have something that could at least do pixel averaging.

Posted by Geoff Jones (Member # 3668) on 05-15-2017, 07:27 PM:

Thanks for the explanation Dave Macaulay. That's helpful. It reminds me of the "rainbow artifacts" that you get from DLP projectors. Some people are more sensitive to those than others. I see them, but when I was shopping for my first digital projector, I remember thinking that even if I didn't see them, I wouldn't want a projector that might look bad to some of my guests.

Posted by Marcel Birgelen (Member # 6801) on 05-15-2017, 07:43 PM:

quote: Joe Redifer
Are they using nearest-neighbor scaling, thus resulting in non-uniform pixel sizes across the screen? Like, did they just buy a cheap HDMI scaler made in China off of Amazon? You'd think they'd have something that could at least do pixel averaging.

The non-square pixels are a result of their weird setup.

Their projectors use industry-standard TI DLP chips. I'm not sure if they use 4K DCI or 4K UHD chips, but either way, they don't come in the aspect ratio of 1.43:1.

So, in order not to waste too much light, they're using anamorphic lenses to stretch the image vertically, instead of horizontally.

In order to make a normal DCP with "square pixels" fit on screen, you obviously need to rescale it. So, the weird vertically stretched pixels are a result of the anamorphic setup.

The scaling wasn't nearest neighbor scaling, it was obviously a bit more sophisticated bilinear or bicubic affair, but it still resulted in pretty ugly artifacts. Maybe their scaling algorithm didn't properly account for the anamorphic nature of the scaled image.

I'm not sure if Alien: Covenant is a 4K release. Many scenes seem to be shot on the Alexa XT, which isn't a 4K or 4K+ camera. Also, we were watching a pre-release show.

Maybe, we were watching the "ordinary" DCP and not the DCP with "IMAX magic" enabled. Still, that would make no real sense, because I clearly heard the IMAX 12-channel sound system in action. Also, the IMAX feature trailers in front of the actual feature had identical issues.

quote: Geoff Jones
Thanks for the explanation Dave Macaulay. That's helpful. It reminds me of the "rainbow artifacts" that you get from DLP projectors. Some people are more sensitive to those than others. I see them, but when I was shopping for my first digital projector, I remember thinking that even if I didn't see them, I wouldn't want a projector that might look bad to some of my guests.

I think all people are almost equally sensitive to laser speckle, although some might not be sufficiently irritated. My girlfriend called it rainbow dots and she also was pretty irritated by their presence.

The rainbow effect is only present in single-chip DLP projectors with color wheel. It's usually much more pronounced in older models than in modern models and some people apparently cannot see it and others do see it, but don't mind the defect. I personally cannot stand it.

It's the same thing you get when you look at a bright laser pointer on a bright surface. You'll see something that looks like a lot of small dots. Now, imagine this in three colors and then you have an idea how speckle looks like in a 3DLP laser setup.

Posted by Dennis Benjamin (Member # 1137) on 05-15-2017, 09:17 PM:

I will forever question this whole screen shaking thing.

Posted by Tom Bert (Member # 5719) on 06-19-2017, 04:48 AM:

Note that screen vibration as a way to mitigate speckle is closely related to the screen gain, type (white vs silver) and brand.

We have hundreds of RGB laser installs running perfectly on everything from 1.0 white to 2.9 silver. However, some high gain silver screens (typically >2.0) of some brands suffer from visible speckle.

I do not know this for a fact, but Dolby Cinema and IMAX might use these screen types. Or it could be that they just add the screen vibration to improve the overall effect (there is no negative impact)

Posted by Steve Guttag (Member # 268) on 06-19-2017, 07:38 AM:

I'd be surprised if Dolby Cinema used a silver screen or even a very high gain (if any gain at all). With Dolby Cinema one uses Dolby 3D which doesn't need (nor want) silver. Gain screens rarely improve light but often make it worse. Sure you get that bright spot in the middle, to the detriment of everywhere else.

Posted by Frank Angel (Member # 248) on 06-19-2017, 07:52 AM:

I won't question that -- you've seen this shaker system in action, but it just seems so counter-intuitive. The sound system in my car has a hefty Bose subwoofer, and when I kick it up loud enough, the rear-view mirror vibrates. Now, if look just at the frame, it's vibrating so minutely that you can't visibly see the virbation, but look at the image and it is severely distorted; touch it with your finger and it is barely moving, certainly fractions of a millimeter. It just seems hard to believe that vibrating the screen in and out wouldn't cause some degradation of resolution.

Posted by Marcel Birgelen (Member # 6801) on 06-19-2017, 09:26 AM:

You have to account for the scope of it all. A screen that moves just about a millimeter in and out of the focus plane will most likely not leave visible artifacts at normal seating distances, especially given the size of those screens.

So, while it would technically potentially degrade focus, I doubt human vision will be able to resolve it. The potential side-effect of the absence of such a system is also massively more annoying than a slightly weak focus.

quote: Steve Guttag
I'd be surprised if Dolby Cinema used a silver screen or even a very high gain (if any gain at all). With Dolby Cinema one uses Dolby 3D which doesn't need (nor want) silver. Gain screens rarely improve light but often make it worse. Sure you get that bright spot in the middle, to the detriment of everywhere else.

Dolby Cinema doesn't use silver screens. I don't know about the gain factor, but I'm pretty convinced it's close to 1.

Posted by Alan Gouger (Member # 543) on 06-19-2017, 11:31 AM:

quote: Tom Bert
We have hundreds of RGB laser installs running perfectly on everything from 1.0 white to 2.9 silver. However, some high gain silver screens (typically >2.0) of some brands suffer from visible speckle.

Tom are the silvers all using vibrators. Can you mention or PM a Silver screen manufacture that you prefer. Thank you!

Posted by Carsten Kurz (Member # 5396) on 06-19-2017, 06:17 PM:

IMAX screens converted to lasers previously used silver screens for 3D. At first, it seems natural to leave them in, even if the do rebuilding of the front speakers as well, and even if they do not need them for 3D any more (IMAX laser 3D is color separation, not polarization). BUT when you look at the speckle these screens show, it appears as a very bad decision. I can only assume even their dual laser projector setup is not bright enough to use a lower gain screen, so they stick with it. I know one IMAX laser installation that started operation with the pre-existing silver screen, and after some weeks, received a NEW silver screen...nuts...

- Carsten

Posted by Marcel Birgelen (Member # 6801) on 06-20-2017, 06:44 AM:

Installing a new silver screen, to keep the existing 3D setup operational might be a valid reason to keep using a silver screen.

Then again, the Brussels theater never had a 70mm dual-projector setup. The image, despite being a dual laser setup, wasn't overly bright, nothing compared to the Barco 6P and Dolby Cinema setups I've seen until now. So, maybe the silver screen is needed to achieve the necessary brightness.

I can't help it, but to me "IMAX" for motion picture presentations still feels like a hack. The native screen aspect ratio doesn't fit any common movie format very well, the oversized screens and difficult room geometry most likely also introduce all kinds of challenges to get the sound right.

Posted by Jarod Reddig (Member # 6363) on 06-20-2017, 05:54 PM:

Sounds like a terrible movie going experience. Everything from the toilets to the presentation. Do other businesses such as restaurants and gas stations charge their customers for restroom use in that part of the world? Unreal.

My first experience with a Dolby Cinema had an issue too. It was so far out of focus it was almost as if the projectors got bumped cause it wasnt framed correctly either. It was at the Barrywoods AMC Dolby Cinema/Prime room in Kansas City for Inside Outs opening weekend. I complained thru email after and they corrected the issue. Ive been back since and it was a great presentation except for the aisle lights runied the contrast on the bottom corners of the screen by spilling onto the screen.

Posted by Tom Bert (Member # 5719) on 07-24-2017, 08:06 AM:

"are the silvers all using vibrators. Can you mention or PM a Silver screen manufacture that you prefer"

Only a minority uses screen vibration. Sticking to gain 1.7 or 2.0 is usually perfectly OK. However, there are installs with 2.9 gain (and without vibration) that also look great.