Film-Tech Forum ARCHIVE: IMAX Laser anamorphics?

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Posted by Carsten Kurz (Member # 5396) on 02-12-2016, 04:14 PM:

SW7 had a 2min sequence of the Millenium Falcon excaping into space presented in full 'classic' IMAX 1:1.43 aspect ratio. That classic full screen aspect ratio is said to be accomplished using anamorphic lenses, stretching the native 4k/1.89AR image vertically to full screen.

Does someone know how fast these anamorphics are dropped into place? Is it possible to do this at runtime, so that the anamorphics would only be put in place for this 2min sequence?

I doubt this is possible without noticing it (an anamorphic sliding in, no matter at what realistic speed, would create a huge visible image warp on those giant screens). Even if happening within a fraction of a second, this certainly should be visible to the audience. I haven't seen this when watching SW7 in a Laser-IMAX recently.

So, if dynamic anamorphic use is not possible, that would mean SW7 would have to be presented through the anamorphic lenses for most of it's runtime, only to have these 2min of glory during the full format scenes?

That would also mean, during the normal scope footage, the effective vertical imager resolution would be drastically reduced against the native vertical imager resolution of 2160 pixels, because only part of an 1.43 image area and pixel count can be used. In scope, even less... And then, it is only a 3D/2k DCP/Master to start with...

Has anyone seen these IMAX laser anamorphics in real? Does someone know wether they are in place throughout the feature?

- Carsten

Posted by Victor Liorentas (Member # 5272) on 02-12-2016, 06:21 PM:

I saw the movie this way and can't believe any lens was dropped in position for those couple of sequences.
It did fill the traditional vertical Imax height (during the 15/70 sequences)with Liemax laser.
It was great for digital 3d but Imax 15/70mm in 2d is still better ie The Dark Knight Rises type of presentation.

I saw a type of speckling but it was very minimal.

Posted by Bill Brandenstein (Member # 7758) on 02-12-2016, 10:53 PM:

My apologies to any who've seen my complaints elsewhere, but Carsten, I thought the image quality of STFA in laser Imax was poor enough as to significantly erode the value of having it Imax. Don't get me wrong - laser rocks. It's 2K that wrecks it.

So, I totally concur with Victor's assessment. And thus (do the math!) it appears that those who saw it in 15/70 Imax, in spite of the 2K DI source, got slightly better resolution than those of us seeing in laser Imax. (Except that chase scene. Why aren't we hearing more about people noticing the one 15/70 pin-sharp scene? Or wasn't it?)

Posted by Carsten Kurz (Member # 5396) on 02-13-2016, 05:55 AM:

You are certainly right in that SW7 is no reference for IMAX Laser, however, it wasn't THAT bad for a 2k production. Most preshow trailers were worse.

The location I saw SW7 at played an IMAX 3D trailer before the main feature. It was CGI only, but it showed what is possible with regard to sharpness, contrast and 3D separation.

What I don't understand ist that the two german IMAX laser locations still keep the metallized screens. They produce a nagging texture on all bright scenes. Berlin had a silver screen before they installed IMAX laser, and that has been replaced by ANOTHER silver screen between the Laser install and the SW7 start. I have no idea why they do this. Do they still need the high gain, even with the laser projectors, or are they not sure about the Dolby Laser 3D solution and want to keep an option on polarizing 3D? If they had white screens, image quality would improve considerably.

I haven't been impressed by their new sound system. I saw SW7 with ATMOS as well, and for an action flic, ATMOS does the better job in vivid and dynamic surround effects.

- Carsten

Posted by Cameron Glendinning (Member # 3516) on 02-13-2016, 10:15 PM:

When I did the late night test of the Millennium Falcon sequence for the Fan Event, a few weeks before its release that Harrison Ford attended at Sydney IMAX. The xenon digital expanded from scope to 1.9. I was told be a Bad Robot staff member that only the 70mm versions filled the screen. Laser did not. We ran the 70mm version and indeed it did fill the square screen.

The Print looks pretty good, there are a few soft shots mostly with the Rebel scenes using 1970's vintage lens elements.

I'm assuming that the silver screen has stayed so that they can get enough light when using the anamorphic to fill the squareish IMAX screen from its 1.9 DLP native ratio, so that the legacy 15/70mm documentaries can still screened on the replacement technology..

Posted by Carsten Kurz (Member # 5396) on 02-15-2016, 07:21 PM:

They could use higher gain non-silver screens. Silver screens are still more expensive that perlux screens. More expensive to transport and mount as well.

- Carsten

Posted by Bill Brandenstein (Member # 7758) on 02-17-2016, 03:16 PM:

Interesting thoughts, guys. I'm normally so annoyed with silver screen hotspotting that I can't help but to notice it right away. But at AMC Universal Imax, I didn't. Maybe I was just distracted by everything else. Now I'm curious if it's still a silver screen there or if it was replaced during that week it was completely closed before "Spectre."

Posted by Mark Gulbrandsen (Member # 72) on 02-17-2016, 03:45 PM:

quote: Carsten Kurz
More expensive to transport and mount as well.

Perlux and Silver should be treated as though they are one and the same for shipping and installation. They ARE packed the same in this country and Canada. I did one (MDI) gain screen once that came in a box and I can still tell five years later where those folds are from being boxed. Screen companies sales are slow and they may tell you anything that seems reasonable to get a sale. DO NOT BELIEVE THAT!

Spend the extra money and have it rolled and shipped in a tube. How often you gonna be replacing that screen? Ten years, fifteen years or longer is the average.

Now Severtson is saying similar tunes on a screen I just ordered... we can ship it in a box. NO THANK YOU!

Works ok for Matte White IF the screen is immediately installed. Any screen shipped in a box you let sit too long is never going to be right.

Mark

Posted by Gary Lightfoot (Member # 8842) on 02-18-2016, 09:12 AM:

Sorry if I missed it, but how was it done? Only for 70mm presentations, or was the anamorphic lens in place the whole time? If an A lens was used, I too think that it had to be there the whole time and not just dropped in for that particular sequence.

Posted by Carsten Kurz (Member # 5396) on 02-18-2016, 03:42 PM:

We're talking about the use of an anarmorphic lens on IMAX' new laser projection systems. They have a native 1:1.89 aspect ratio, but allow to stretch the image vertically to the classic IMAX 1:1.43 aspect ratio by using an anamorphic lens.

Question was: If they show a mainstream movie with a scope aspect ratio that has 'some' native IMAX scenes in it like SW7, are they able to slide in the lens 'on the fly', or will that lens have to be in place throughout the whole movie, thus compromising the native 1.89/4k projection system quality for the whole movie JUST because there are 2min worth of 1.43 footage in it?

- Carsten

Posted by Gary Lightfoot (Member # 8842) on 02-18-2016, 04:23 PM:

Hi Carsten, thanks for clarifying.

I would have thought it would have been easier just to leave it in place because otherwise moving the lens in and out would be very visible each time (in, then out), but as you say, it does reduce the pixel density through the rest of the movie too, but at least it's constant, and no change in image brightness either.

would be nice to know if that was the case though.

Posted by Bill Brandenstein (Member # 7758) on 02-18-2016, 08:52 PM:

I'm guessing, based on what we saw, that it's in place the whole time.

Posted by Carsten Kurz (Member # 5396) on 02-19-2016, 01:09 PM:

Yes, I think, not matter how fast, you would still see it given the size of the screen. The only way to hide it would be to have a few seconds of black when it slides in or out.

- Carsten

Posted by System Notices (Member # 2357) on 03-07-2017, 02:41 PM:

It has been 382 days since the last post.

Posted by Pat Caldwell (Member # 9903) on 03-07-2017, 02:41 PM:

Interesting suppositions going on here. My perspective? Different. [Smile]

Posted by Bill Brandenstein (Member # 7758) on 03-07-2017, 04:40 PM:

Really? Like what?

(Troll?)