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JVC RS4500 (native 4K laser projector)

AVSCraig

Re: JVC RS4500 (native 4K laser projector)
« Reply #465 on: February 05, 2017, 03:35:41 AM »
I finished installing a new front panel for the RS4500 today, and moved our seating closer still to the screen ( why not ) !





More tomorrow - it's late !

mark_h

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Re: JVC RS4500 (native 4K laser projector)
« Reply #466 on: February 05, 2017, 04:23:45 AM »
One other item I noticed, which is very similar to Sony units of the past. Previous Sony units like the 1100ES and the other smaller 4K units, have had issues where the Blue panel was out of convergence for the first 15 mins or so, then it would settle in.

I am seeing this exact same thing on the JVC.

This might also improve over time, but if not at least it seems to settle into place as the unit warms up.

One of the things that struck me on first starting up mine was there was no convergence errors at all, nor after some hours of use.  My Sony 1000 was -8 out on blue and converged a little as the projector warmed up.  The Z1 seems stable.  Maybe I struck lucky with mine.

One issue that seems to affect my Z1, as it did my Sony, is that focus seems to drift between sessions, so I shut the unit down with focus spot on, but the projector then starts with focus off.  I then have to check focus each time I start and refocus if necessary.  I had hoped to say goodbye to that particular problem. 
My cinema: The Cave

AVSCraig

Re: JVC RS4500 (native 4K laser projector)
« Reply #467 on: February 05, 2017, 11:20:51 AM »
One of the things that struck me on first starting up mine was there was no convergence errors at all, nor after some hours of use.  My Sony 1000 was -8 out on blue and converged a little as the projector warmed up.  The Z1 seems stable.  Maybe I struck lucky with mine.

One issue that seems to affect my Z1, as it did my Sony, is that focus seems to drift between sessions, so I shut the unit down with focus spot on, but the projector then starts with focus off.  I then have to check focus each time I start and refocus if necessary.  I had hoped to say goodbye to that particular problem.

I will check for that. Maybe focus changes after it warms up ?

mark_h

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Re: JVC RS4500 (native 4K laser projector)
« Reply #468 on: February 05, 2017, 11:49:13 AM »
I will check for that. Maybe focus changes after it warms up ?

I'm thinking it's a heat issue.  When you turn the projector OFF it just sits there and stews in its own heat...   I'm going to experiment with running the cold feed for 30 minutes or so after a session to help cool/evacuate all the heat and see if that helps things.  It's a shame my air feed isn't on the Crestron so that I could automate it.
My cinema: The Cave

Re: JVC RS4500 (native 4K laser projector)
« Reply #469 on: February 05, 2017, 01:13:36 PM »
With the RS4500, I tried the HDR preset, and I also tried BT.2020, which on my sized screen(s) is do-able. I've come to the conclusion that Kris Deering's suggestion to watch 4K Blu Rays using Rec. 709 just looks more natural. You still get the added detail and clean noise free picture thanks to 4K, and Rec 709 using the natural preset is brighter.

How exactly are you handling this? Are you having the UHD BD player send UHD HDR REC2020 to the projector and just putting the JVC in it's REC709 preset mode? Or are you having the color points truncated from REC2020 to REC709?
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Re: JVC RS4500 (native 4K laser projector)
« Reply #470 on: February 05, 2017, 01:24:24 PM »
How exactly are you handling this? Are you having the UHD BD player send UHD HDR REC2020 to the projector and just putting the JVC in it's REC709 preset mode? Or are you having the color points truncated from REC2020 to REC709?

I'm almost certain he is just outputting SDR REC709 from the Bluray player, since there is an exact specification for how the players convert HDR2020 to SDR709.

AVSCraig

Re: JVC RS4500 (native 4K laser projector)
« Reply #471 on: February 05, 2017, 04:49:30 PM »
How exactly are you handling this? Are you having the UHD BD player send UHD HDR REC2020 to the projector and just putting the JVC in it's REC709 preset mode? Or are you having the color points truncated from REC2020 to REC709?

Somebody mentioned that you could do this with the Panasonic UB900, but they never specifically said how to do it. Turns out, you just turn HDR off in the UB900 !

Re: JVC RS4500 (native 4K laser projector)
« Reply #472 on: February 06, 2017, 10:40:30 AM »
I'm almost certain he is just outputting SDR REC709 from the Bluray player, since there is an exact specification for how the players convert HDR2020 to SDR709.

I talked to someone at Oppo about this and learned while converting HDR2020 to SDR709 is in the UHD BD spec, it's still complicated.  I discussed with them how the BD and UHD BD even at rec 709 still have different looking gammas (at least on the Oppo) on several movies I closely compared (running the BD in the 103D and UHD BD in the 203 into different inputs A/Bing the scenes at the same time essentially on my RS500).  I see shadow detail crushed and color still a little off at times on the UHD BD at SDR709.  Sometimes a little too much contrast probably from the gamma conversion.  Basically I was told that a conversion curve is needed to match all the values from an HDR signal into the SDR range.  In theory, the player has the potential to restore the same gamma as the BD, however there isn't a "perfect" algorithm for converting an absolute luminance into the relative luminance yet.  So there is going to be some variance and probably some tweaks to optimize this.
« Last Edit: February 06, 2017, 10:52:33 AM by DavidHir »

mark_h

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Re: JVC RS4500 (native 4K laser projector)
« Reply #473 on: February 06, 2017, 10:54:27 AM »
Which is why the Lumagen process looks exiting.  They hold the 3D cube for your display so can map the HDR into it.  Should be the best possible way to convert HDR.
My cinema: The Cave

AVSCraig

Re: JVC RS4500 (native 4K laser projector)
« Reply #474 on: February 06, 2017, 11:27:11 AM »
I talked to someone at Oppo about this and learned while converting HDR2020 to SDR709 is in the UHD BD spec, it's still complicated.  I discussed with them how the BD and UHD BD even at rec 709 still have different looking gammas (at least on the Oppo) on several movies I closely compared (running the BD in the 103D and UHD BD in the 203 into different inputs A/Bing the scenes at the same time essentially on my RS500).  I see shadow detail crushed and color still a little off at times on the UHD BD at SDR709.  Sometimes a little too much contrast probably from the gamma conversion.  Basically I was told that a conversion curve is needed to match all the values from an HDR signal into the SDR range.  In theory, the player has the potential to restore the same gamma as the BD, however there isn't a "perfect" algorithm for converting an absolute luminance into the relative luminance yet.  So there is going to be some variance and probably some tweaks to optimize this.

On my RS4500 I'm seeing more shadow detail for sure than on my RS600. I'm finding that with the HDR preset I have to really open up the manual iris quite a bit for the picture to look as bright as when watching with Rec.709. Anyway, it can look good either way ! Watched " Enders Game " on 4K BR last night ( guests movie choice since they help me install the projector Friday ). Amazing amount of detail - the last 1/3 where they attack the Formic's home planet was especially impressive !

mark_h

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Re: JVC RS4500 (native 4K laser projector)
« Reply #475 on: February 06, 2017, 12:05:16 PM »
On my RS4500 I'm seeing more shadow detail for sure than on my RS600.

I'd be inclined to say this is a calibration issue...   with proper calibration, especially a 3D LUT, both should display the same shadow detail.
My cinema: The Cave

AVSCraig

Re: JVC RS4500 (native 4K laser projector)
« Reply #476 on: February 06, 2017, 12:48:44 PM »
I'd be inclined to say this is a calibration issue...   with proper calibration, especially a 3D LUT, both should display the same shadow detail.

I had some black crush on the RS600 - no doubt.

mark_h

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Re: JVC RS4500 (native 4K laser projector)
« Reply #477 on: February 06, 2017, 01:13:14 PM »
I had some black crush on the RS600 - no doubt.

Have you considered switching to a 3D LUT?  This pretty much resolves all such issues...

My cinema: The Cave

Re: JVC RS4500 (native 4K laser projector)
« Reply #478 on: February 06, 2017, 02:40:00 PM »
I had some black crush on the RS600 - no doubt.

That is only a calibration issue, actually the RS600 will show better shadow detail when calibrated to to the same gamma with perfect brightness due to its far superior on/off contrast. :)
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Andreas                                                           

Calibration software: Lightspace and Calman. TPG: Murideo Fresco SIX-G
Meters: Klein K-10 A and Jeti 1501. THX II certified.

AVSMike

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Re: JVC RS4500 (native 4K laser projector)
« Reply #479 on: February 06, 2017, 11:26:45 PM »
RS4500 arrived. :)
« Last Edit: February 06, 2017, 11:28:27 PM by AVSMike »
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