Film-Tech Forum ARCHIVE: Christie laser projector mis-registered?

This is topic Christie laser projector mis-registered? in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=16;t=003834

Posted by Jonathan Smiles (Member # 926) on 10-23-2019, 09:37 AM:

Is mis-registration easily fixable on Christie laser projectors?

Don't know model of projector but it will be a standard model for a 200 odd seat theater with stadium seating. It's a new plex with all laser projection and laser IMAX.

Images such as white text have a red bottom edge and green top edge and it's visible on high contrast edges such as over actor's shoulder etc.

Can it be fixed remotely as the plex has no projectionists or techs on site?

Posted by David Gibbons (Member # 10887) on 10-23-2019, 10:27 AM:

not sure about laser but it sounds like a convergence issue and that would need to be done onsite

Posted by Sean McKinnon (Member # 612) on 10-23-2019, 12:21 PM:

Christie offers digital convergence but I would definitely call a qualified D-Cinema tech in to manually perform the convergence calibration.

Posted by Marcel Birgelen (Member # 6801) on 10-23-2019, 02:32 PM:

Projector converge can be off, no matter if the light source is Xenon, phosphor-laser or n*3P-laser. It's an easily fixable problem, as long as you let a competent tech do the re-calibration.

If one or more of the 3 DMDs don't properly align, you get a "rainbow shadowing" effect in different colors, depending on the affected colors. Those are especially good to see around hard edges.

Posted by Mark Gulbrandsen (Member # 72) on 10-24-2019, 09:05 AM:

I would definitely call a qualified D-Cinema tech

Posted by Andrew Carr (Member # 9264) on 10-24-2019, 11:00 AM:

Which model is it? Convergence on the newer Christies is really simple. On the Boxers and larger RGB units they give you a test pattern with instructions on screen and there are both tools packaged in a compartment in the body and tool-less adjustment points inside the service door. Very easy to do.

EDIT: Just re-read, you don't know the model. If you can ask someone on site to get you that info, take a look at the manual and determine if you need to hire a tech. It's very hard to mess up though...

Posted by Carsten Kurz (Member # 5396) on 10-24-2019, 11:14 AM:

I think there is a software convergence tool now accessible though the touchscreen. I guess this can be used as a temporary measure, even remotely, if a tech can't make it to the location in time. This per-pixel correction should at least be able to reduce an annoying amount of misconvergence. Of course, given that this machine must be quite new and should have been converged decently from factory and installation, it is also possible that the software convergence is the actual cause of this issue if someone messed with it...

- Carsten

Posted by Jonathan Smiles (Member # 926) on 10-27-2019, 02:55 PM:

Thanks all,

Jonathan
http://www.imdb.com/name/nm1211866/

Posted by Jonathan Smiles (Member # 926) on 11-21-2019, 03:34 PM:

A month after opening and still convergence issues on the non-IMAX screens.

One screen has red bottom and green top borders on the edge of the screen as well as red/green halos on edges, it's like anaglphic 3D (I think I still have my Nightmare on Elm Street 3D glasses somewhere).

Another screen was better with smaller red and green blurred halos.

Most staff are apologetic, a few don't care and one said "most people won't notice".

Posted by Stephan Shelley (Member # 8587) on 11-21-2019, 04:09 PM:

When I was a cinemacon in the Christie demo the image looked out of convergence to me. The red was noticeably off. I spoke to the Christie guys there and they assured me it was converged correctly and it was because I wore glasses and the narrow bandwidth of the laser light and that the red got bent differently than the blue and green and it appeared out of convergence. There may be some of this going on here.

I know that the laser projector I installed a Barco 22L I did see some of that but not as bad as the Christie but the 22L is 6P and the Christie was a series 3 3P. More bandwidth with the 6P?

Posted by Marcel Birgelen (Member # 6801) on 11-21-2019, 04:13 PM:

It's in the numbers. [Wink]

6P -> 6 primaries, 3P -> 3 primaries. So, the 6P machine has twice as many primaries.

@Jonathan: Do you wear glasses or other "seeing aids"?

Not intended as a personal question. [Wink]

Posted by Frank Cox (Member # 6258) on 11-21-2019, 04:15 PM:

Sounds like a good reason not to get one of those projectors if the image doesn't look good to people who wear glasses. Google tells me that about 64% of the population of the USA (and probably similar numbers elsewhere) wear glasses.

Posted by Carsten Kurz (Member # 5396) on 11-21-2019, 04:33 PM:

I guess that also some of the common types of optical coatings for glasses would create different amounts of issues. Wow. Never heard about that problem before. At the same time, it would be very unprobably that multiple auditoriums with brand new installations would all exhibit noticeable misconvergence right from the start.

I think Christie has no phosphor lasers (which shouldn't suffer from that issue). So, this may be a real issue...but then, maybe Jonathan uses a very unusual pair of glasses?

- Carsten

Posted by Stephan Shelley (Member # 8587) on 11-21-2019, 05:12 PM:

I have coated lenses in my glasses to reduce reflections.

Posted by Marcel Birgelen (Member # 6801) on 11-21-2019, 07:34 PM:

I've also never really heard about this problem before, but it at least makes some sense.

Refraction isn't just dependent on material, but also on wavelength, that's how we use prisms to split and combine colors in lamp-based projectors, among countless of other applications...

Now, the technology to use some very narrow primaries to reconstruct something that looks like full-spectrum RGB images hasn't been deployed "en masse" before.

We already know that some people are more sensitive for some wavelengths than others, that can create a considerable shift in perceived colors when using a "low primary" laser based solution, but this might be another problem that comes with the technology. I simply didn't expect it to be really noticeable, since the splitting of the beams occurs so short in front of the retina.

So, it might be worth investigating if this is a real problem or if it's just a bunch of badly converged projectors. I agree with Carsten that it's somehow strange that a new complex would end up with a whole bunch of totally misaligned projectors. While not impossible, it would be a really sloppy job.

quote: Stephan Shelley
I have coated lenses in my glasses to reduce reflections.

I don't think the coating will really make a difference, at least as far as I can think about it. The coating should absorb certain wavelengths better than others, but I don't think it will really have an impact on the refraction index.

Posted by Jonathan Smiles (Member # 926) on 11-22-2019, 12:00 AM:

I do wear glasses, back-surfaced digital varifocal lenses with anti glare and photochromic.
No issues with 6P laser, Xenon DLP etc.

My prescription is +1.00 to +0.75 for distance.

Huge issue if it is glasses related.

I do have a pair of glasses that are basic distance only prescription I use for VR, which I will take with me next time to test.

Posted by Marcel Birgelen (Member # 6801) on 11-22-2019, 07:08 AM:

So, you still plan to return, despite multiple bad experiences? [Smile]

I guess with only +1.00 and +0.75, you should even be able to see the misconverged images without glasses, especially if it's as bad as you described.

So, I guess it would already be an interesting experiment if you just take off your glasses.

Posted by Jonathan Smiles (Member # 926) on 11-22-2019, 08:09 AM:

I have presbyopia (long-sightedness caused by loss of elasticity of the lens of the eye, occurring typically in middle and old age). Otherwise I have perfect color vision.

I find my distance vision is soft without glasses but did lift them for the first screening and it was indeed mis-converged.

I currently believe I am seeing mis-calibrated convergence in the screens with the large convergence errors, however for the screens with blurred red/green halos this could be the glasses issue on a perfectly converged screen.

As for still going, I have a monthly subscription (all you can eat 2D standard screenings, 12 month minimum contract) and was working on the basis it will get fixed.

Fingers crossed that my basic glasses fix the issue for the correctly converged screens.

Posted by Ken Lackner (Member # 1002) on 11-22-2019, 05:13 PM:

I wear glasses and have always had this problem, but it is significantly worse on RGB laser projectors. (Not sure about phosphor, haven't been around as many of them.) I've been installing a bunch of Barco series 4 (SP4K), and convergence will always appear to be off when I tilt my head. Doing convergence on these absolutely requires a spotting scope (really should always use one, but even more critical here) if the installer wears glasses, or one person standing right up at the screen *without* glasses and communicating to the installer in the booth.

That said, content that I've watched on these projectors does look good. I thought the color separation deal would bother me but it really doesn't.

Posted by Stephan Shelley (Member # 8587) on 11-22-2019, 09:27 PM:

I am going to be installing a Christie series 3 RGB laser projector next month and will see how that goes.

Posted by Sean McKinnon (Member # 612) on 11-23-2019, 08:57 AM:

Yes! You are! And we are very much looking forward to it.

Posted by Pete Naples (Member # 761) on 11-23-2019, 12:18 PM:

My £0.02's worth

RGB lasers, the light is extrememly coherent. Lenses by their very nature are imperfect and cannot possibly focus the visible spectrum in the same place.

We noticed on a site whilst adjusting convergence that two different people see it differently, neither of us were spectacle wearers. I would see a red fringe to white text on black, my colleague would see green.

Posted by Stephan Shelley (Member # 8587) on 11-23-2019, 01:53 PM:

I guess with the 6P projectors where you have both long and short wavelength lasers for each primary color it is not as not as noticeable.

I also notice that the speckle thing is less noticeable with 6P lasers in 2D when all lasers are running continuously. However in laser 3D I noticed it more when the laser were pulse mode. Alternating short and long wavelengths in each primary color. To me most noticeable in red.