Film-Tech Forum ARCHIVE: Subjective picture quality impression. Lcos.

This is topic Subjective picture quality impression. Lcos. 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=003414

Posted by Alan Gouger (Member # 543) on 08-18-2018, 06:56 AM:

The other night I decided to go see the movie Spy Who Dumped me. the theater was an AMC. The screen was silver, curved over 50 feet wide in scope format. During the screening I could detect texture in the center during bright scenes, not too distracting. The picture was very nice with nice colors, very nice contrast and black level with no pixel structure. Light output was just right for such a large screen, yes it could have been brighter but it was bright enough to avoid eye strain. I was impressed with the image quality. I was trying to figure out if I was watching DLP or Lcos. At one point the movie went all black and then I knew it was Lcos. At the bottom left corner of the screen black had a red shading issue. This was the only time during the movie this was visible. Looking through the portal I could not tell if this was the older 320 or a 515/815 but other than the few seconds of red tint I was impressed with the picture quality. Very analog and film like.
What is the point, I am not trying to start a DLP verses Lcos war I just wanted to post my impression while everything was still fresh in the memory bank. The majority of all movies I see use DLP so for me it was a treat to see Lcos on a large screen.

Posted by Marcel Birgelen (Member # 6801) on 08-18-2018, 05:09 PM:

Both technologies have their advantages and obvious disadvantages.

I'd say that in the general look and feel of the picture, LCoS or SXRD looks a little bit more "film like". Since the space between the individual pixels is smaller, there is also less of a pixel grid.

LCoS in general tends to have better black levels than DLP, which adds to the "film look".

LCoS doesn't pulsate light the way DLP does. In general it's accepted that the pulsation of individual (sub)pixels happens at a frequency which is far above the flicker fusion rate of humans, so it should not be noticeable. Yet you could call the advantage of LCoS that it just needs to adjust the "reflectivity" of the mirror surface and therefore doesn't need to pulse light, it acts more like a light valve for every (sub)pixel, much like LCD does.

One of the biggest issues of LCoS panels is that they behave much like CMOS panels. They need to be constantly calibrated or they'll start to misbehave.

Whereas a modern digital camera automatically "calibrates" themselves after every shot by making a picture with the iris closed, projectors don't have that luxury. So, many LCoS type projectors often never have their panels "gamma calibrated", that's when things start to get out of whack. Sometimes it can even go so far that you see discolored patches on screen.

Posted by Monte L Fullmer (Member # 2797) on 08-21-2018, 06:12 PM:

Bet it was DLP.

For Sony are limited to 4k bulbs and 45 foot wide screen is their limit.

Plus, Sony uses the twin lens setup for 3D and leave both lenses intact for the regular and 3D presentations.

Prob was a Barco unit since they can really get the light out.

You get high contrast on a silver screen.

Plus, silver screens eats light is why you think the pict could be brighter.

Posted by Marcel Birgelen (Member # 6801) on 08-22-2018, 04:27 AM:

You can stack Sony projectors for both 2D and 3D purposes.

Also, I've seen Sony projectors being used in single setup on high-gain screens of roughly 50 ft. width. I doubt it will meet the specs at the end of the cycle of the lamp though...

Posted by Dave Macaulay (Member # 813) on 08-22-2018, 11:42 AM:

From my experience AMC was not too concerned with meeting optimum image quality. Or sound quality... using a somewhat underpowered Sony projector would not surprise me.
I could never understand their affection for Sony cinema equipment. Few cinema processors had worse SR decoders than theirs, and not all features came with SDDS tracks.

Posted by Monte L Fullmer (Member # 2797) on 08-22-2018, 04:19 PM:

quote: Dave Macaulay
I could never understand their affection for Sony cinema equipment.

Sony cut these circuits a horribly huge deal if they ripped out their 35mm stuff and went with them.

Their company techs pleaded otherwise, but the bean counters doesn't think that way - all about the $$$ sign.

Posted by Mark Gulbrandsen (Member # 72) on 08-22-2018, 05:05 PM:

There IS no war on DLP vs LCOS any longer. DLP won out over 12 years ago. The only thing LCOS can do over DLP is absolutely black. But there isn't a theater on the planet that has stray light levels low enough to really take advantage of that absolute black level. Otherwise LCOS strains just to light up a 50 foot wide screen... yours was silver just to give the impression of a decently lit image. The reality of silver screens is dismal at best with hot spotting and poor light distribution. New AMC and Regal builds no longer install Sony, at least not the one they built near me here in Nashville and Salt Lake City. The other still extant issue with LCOS is the chips baking in the heat and turning brown. Watching a movie for one of these projectors is awful to say the least. Then you have the crappy 3-D system...

quote: Marcel Birgelen
You can stack Sony projectors for both 2D and 3D purposes.

Sure! And end up with twice as crappy an image! Sans doing this for 3-D on a giant screen as I have in the past you still get poor convergence of the two images which is inescapable in any dual projector installation.

Mark

Posted by Alan Gouger (Member # 543) on 08-22-2018, 05:21 PM:

This was definitely a Sony projector, the shading issue in the bottom left corner was the give away and was only visible for a few seconds during the entire movie otherwise I was quit impressed with the picture quality. This was one of the few times I experienced Lcos on a large screen as most of my screenings are at DLP driven theaters. As mentioned it was very film like.

Posted by Monte L Fullmer (Member # 2797) on 08-22-2018, 06:20 PM:

quote:
I was quite impressed with the picture quality

Just did a bulb install then if the pix was good.

For Sony's with their horrendous exhaust systems, bulbs are only good for the first 300 hours of their life and then fade to flat afterwards.

Posted by Lyle Romer (Member # 1266) on 08-22-2018, 07:45 PM:

quote: Mark Gulbrandsen
New AMC and Regal builds no longer install Sony, at least not the one they built near me here in Nashville and Salt Lake City.

Regal used to have "Sony 4k Presentation" or something like that on their feature presentation snipe. I can't remember the last time I saw that. I don't think it's been on any of the cheesy "student film" snipes.

Posted by Monte L Fullmer (Member # 2797) on 08-23-2018, 02:25 PM:

quote: Lyle Romer
"Sony 4k Presentation"

For indeed, the Sony SRX-R320 units were 4k projectors.

Just that the content was still 2k ... and the majority of the content, presently, is still 2k content.

Thus, that 4k meant nothing since the image on the screen was still a 2k image being displayed by a 4k projector.

Posted by Carsten Kurz (Member # 5396) on 08-23-2018, 03:45 PM:

Trust me Monte, if you see a 2k feature on a 2k DLP projector vs a 2k feature on a 4k SXRD projector, you will notice the difference. At least as long as you are not just peeking through the port hole.

- Carsten

Posted by Mark Gulbrandsen (Member # 72) on 08-23-2018, 03:57 PM:

quote: Lyle Romer
Regal used to have "Sony 4k Presentation" or something like that on their feature presentation snipe. I can't remember the last time I saw that. I don't think it's been on any of the cheesy "student film" snipes.

Yes, the first time round for both Regal and AMC they installed Sony on all their screens up to about 40' wide and put DLP on screens over that size... for obvious reasons. Why did they install SOny? Because Sony GAVE THEM the projectors and collected the VPF loot.

quote: Carsten Kurz
At least as long as you are not just peeking through the port hole.

In theory, at many theaters, the porthole is the best spot to watch a movie.

Mark

Posted by Monte L Fullmer (Member # 2797) on 08-24-2018, 03:00 PM:

Ive seen 4K through a 4K 320 unit when 4k was first coming out. Total difference - much clearer pict and sharper.

Course, we have to thank the labs on their scanning procedures being the content originated on film.