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Tim in Phoenix
Joined: 21 Oct 2006
Posts: 4409
Location: Phoenix
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| Posted: Tue May 29, 2012 3:31 pm Post subject: |
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| mp20748 wrote: | | Tim in Phoenix wrote: | Guys
For edge blending and displaying 1920 pixels with a 20% overlap, each projector need only resolve 60% of the 1920 pixels or 1152 pixels; a seven inch CRT can manage that.
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You're right Tim. But 1151X1050 when going at 72hz, the bandwidth requirements are far beyond what any 7" projector will do, with only the 8" Marquee almost having enough bandwidth to properly display the finer detail.
The discussion deals primarily with Bandwidth requirements. |
I am sure you are right Mike; but I watch movies on my system, not single pixel on-off test patterns. Using seven inch projectors for blending is not suggested, but you would likely have a watchable image, better than one seven inch projector.
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mp20748
Joined: 12 Sep 2006
Posts: 5689
Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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| Posted: Tue May 29, 2012 3:36 pm Post subject: |
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| Boilermaker wrote: |
| Quote: | | Who said anything about lower scan rates? You still want 1080p; the requirement for 1920 is reduced |
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Exactly! Thanks Tim. Nuff said.
Bob |
The math is 100% correct. And since your system should and without a doubt 100% resolve 1920X1080P, then it would far exceed any CRT projection setup. And it would also project the finest detailed image of any CRT projector out there, because it would be able to NOT have the bandwidth limitations of native 1080P HD.
Meaning a blending dual 8" CRT projector setup should have the sharpest and most defined image out there, because it is properly resolving 1920X1080P correct?
Once more, either you or Nash, produce a screenshot showing this resolution being properly resolved.
Show me a screenshot that shows this level of sharpness and detail and I'll agree..
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VideoGrabber
Joined: 09 Apr 2006
Posts: 933
Location: Michigan
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| Posted: Tue May 29, 2012 4:06 pm Post subject: |
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| Boilermaker wrote: | | Not only can it do it, it is actually much easier to do than running 1080P on a single projector. There are two reasons for this. |
Thanks, Bob. I appreciate the followup, and explanations.
| Quote: | | First, because (in the case of 1920X1600) each projector only "sees" 1064X1600, the bandwidth requirement is substantially lower than 1920X1080. |
I agree. About 20% less, in fact. However, that makes the assumption that the original 8" PJ was capable of handling 1920x1080px72 in the first place. Other than a few tweaked out by MP, I wasn't aware they existed in the wild.
| Quote: | | At 1064X800, the video frequency is less than conventional 1080i!!! |
Yes, that's true. Though not too surprising. But we were discussing 1600p. So correspondingly, at 1064x1600, the video frequency is less than 1080p. But if the PJ couldn't handle 1080p in the first place, there's no guarantee that 1600p would be a piece of cake.  Even dropping the BW required by 20%.
| Quote: | | Secondly, in a conventional setup when you are watching a 2.40 source, you are using less than 1/2 the height of the tube face available. |
Yes, I know. Which is why I suggested (back in the A-forum, perhaps 7-8 years ago) a possible solution for CRTers wanting to do CIH would be to shift their raster up, use half the tube face, then shift it down and use the other half. I think someone suggested I was crazy.  [It would have required tilting the PJ off the horizontal.]
| Quote: | | In a blend, you are using the entire (or as close to the edge as you want to take it) height. Also, you are only recreating 1064 pixels across the width in comparison to 1920. An 8" projector can handle this easily. |
It can certainly handle 1064 horizontal pixels easily, under normal conditions. I'm just not so sure about at the 120 kHz scanrates required for 1600p at 72 Hz. Which is why I asked.
| Quote: | | ...since a blend gets to use the entire tube, running just 1080P there are visible scan lines everywhere on the screen. |
I hadn't thought about that, but yes, that could be true. Depending on beam-spot size and % of tube face utilized (how you define full).
| Quote: | | Try watching a 2.4 movie, and adjust your vertical gain until it fills the tube face and you will see it for yourself. |
Well, that would be stretching 800 lines to fill the vertical, not 1080.
| Quote: | | The projectors are just loafing at these rates which is one reason why the picture looks so good. |
Yes, I agree that the picture they create can look phenomenally good. Especially when you don't push too hard on any one parameter, but create a balance. One characteristic I've noted on Barcos (the only CRTs I've ever owned) is the inverse relationship between scanrate and image quality (just talking in broad terms). I.e., as the scan rate goes up, the IQ starts to drop. In other words, there's a tradeoff.
Running any PJ at it max scanrate never seemed like a great idea to me, which is why I inquired about your comment on doing 120 kHz being easy on a 8" PJ. I know it was neither easy nor desirable on my BG808.
_________________
- Tim
Last edited by VideoGrabber on Tue May 29, 2012 4:09 pm; edited 1 time in total
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Boilermaker
Joined: 21 May 2006
Posts: 527
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| Posted: Tue May 29, 2012 4:06 pm Post subject: |
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| Quote: | | You're right Tim. But 1151X1050 when going at 72hz, the bandwidth requirements are far beyond what any 7" projector will do, with only the 8" Marquee almost having enough bandwidth to properly display the finer detail. |
Wrong again - The bandwidth requirement for displaying 1151X1050@72 is only 27% higher than what is required for simple 1080I.
There are numerous 7" projectors that can do a fine job of this.
| Quote: | | Show me a screenshot that shows this level of sharpness and detail and I'll agree.. |
Can't speak for Nash, but I don't give a sh** if you agree.
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VideoGrabber
Joined: 09 Apr 2006
Posts: 933
Location: Michigan
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| Posted: Tue May 29, 2012 4:19 pm Post subject: |
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| Tim in Phoenix wrote: | | For edge blending and displaying 1920 pixels with a 20% overlap, each projector need only resolve 60% of the 1920 pixels or 1152 pixels; a seven inch CRT can manage that. |
Hey, Tim. I don't disagree with that statement, but can it do so with a scanrate at 120 kHz? That's what Bob and I were having a friendly conversation about, but with 8" PJs being the focus.
I'm just trying to wrap my head around how feasible doing 1600p would be, in a pair of blended 8" PJs. Bob indicated it was "easy", and if he's actually doing it, he sure knows a hell of a lot more about it than I do.
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- Tim
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mp20748
Joined: 12 Sep 2006
Posts: 5689
Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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| Posted: Tue May 29, 2012 4:27 pm Post subject: |
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| Boilermaker wrote: | | Quote: | | You're right Tim. But 1151X1050 when going at 72hz, the bandwidth requirements are far beyond what any 7" projector will do, with only the 8" Marquee almost having enough bandwidth to properly display the finer detail. |
Wrong again - The bandwidth requirement for displaying 1151X1050@72 is only 27% higher than what is required for simple 1080I.
There are numerous 7" projectors that can do a fine job of this. |
Really.. what bandwidth calculator are you using?
AMX bandwidth calculator says: 60mhz
And what 7" CRT projector you know of that has that bandwidth rating?
But again and as I said on the previous page, "The discussion deals primarily with Bandwidth requirements"
So to prove a point about low bandwidth 8" projectors being able to handle higher scan rates and vertical rates is not something that going to happen when your goal is to resolve the image and not just display it.
| Quote: | Show me a screenshot that shows this level of sharpness and detail and I'll agree..
Can't speak for Nash, but I don't give a sh** if you agree. |
My my, you mean we won't get to see how well those two projectors can resolve the native image?
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Boilermaker
Joined: 21 May 2006
Posts: 527
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| Posted: Tue May 29, 2012 4:47 pm Post subject: |
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| Quote: | | I agree. About 20% less, in fact. However, that makes the assumption that the original 8" PJ was capable of handling 1920x1080px72 in the first place. |
Point well made. I see two reasons why a good 8" machine would struggle with this rate. First is the frequency of the video signal (which is reduced by the 20% you stated) and second is the physical requirement of squeezing all those horizontal lines in the space used on the tube face. Based on 2.4 AR material, you have twice the space when blended. Admittedly, while 1600 lines using the full tube is roughly equivalent to using the original 800 lines in 1/2 the space with a conventional setup that many people use and are satisfied with, I do not recommend it. As I have stated in previous posts, I run 1200 lines (800 from my DVDO VP50 and then scale to 1200 with my blend boxes). If I had a pair of 9" projectors, I would take it to 1600.
Please note that 1200 is an easy 1.5 multiple of 800, so I see no artifacts. When I use 1280 on 1.78 video sources, I switch to 60Hz refresh and have obvious scan lines everywhere indicating that it has no physical problem at this resolution.
| Quote: | | Which is why I suggested (back in the A-forum, perhaps 7-8 years ago) a possible solution for CRTers wanting to do CIH would be to shift their raster up, use half the tube face, then shift it down and use the other half. I think someone suggested I was crazy. |
I remember your post! I thought it was a good idea, but with a blend it is a non-issue.
| Quote: | | It can certainly handle 1064 horizontal pixels easily, under normal conditions. I'm just not so sure about at the 120 kHz scanrates required for 1600p at 72 Hz. Which is why I asked. |
Can't remember if theMarquee can handle it, but I think it can. I have the135LC's so it is not a problem for me if I were to ever try it.
| Quote: | | One characteristic I've noted on Barcos (the only CRTs I've ever owned) is the inverse relationship between scanrate and image quality (just talking in broad terms). I.e., as the scan rate goes up, the IQ starts to drop. In other words, there's a tradeoff. |
I've never pushed it near my limit, so I have not experienced that. Perhaps if I ever try 3D at 96Hz, it will become an issue. While there are several reasons for the increase in PQ, I would speculate that a good portion of it is because of the greatly reduced video frequency each projector sees. I think that the signal is only down about 1.5 - 2 db at where I am, which is awefully good.
Bob
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mp20748
Joined: 12 Sep 2006
Posts: 5689
Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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| Posted: Tue May 29, 2012 4:51 pm Post subject: |
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I copied a few shots from two years ago that I took of my setup. They are 100% native and un-touched TRUE 1920X1080P @ 72hz coming out of a Radiance Processor into my Moome card that's installed in my Super 9500LC.
The shots show several things at that resolution. 1, what 1920X1080P looks likes at 72hz when properly resolved. 2, when properly resolved, the background with HD should be as distinct as the foregrounds. 3, why I don't need a blend for my room size.
These were taking a few years ago when I had the setup calibrated and also had the Radiance in the video chain...
Sony camera Full 1080P 72hz
Uploaded with ImageShack.us
Uploaded with ImageShack.us
Uploaded with ImageShack.us
Uploaded with ImageShack.us
Uploaded with ImageShack.us
Uploaded with ImageShack.us
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Boilermaker
Joined: 21 May 2006
Posts: 527
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| Posted: Tue May 29, 2012 4:58 pm Post subject: |
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| Quote: | AMX bandwidth calculator says: 60mhz
And what 7" CRT projector you know of that has that bandwidth rating? |
Actually, probably several, but I no longer mess with any 7" as you can get an 8" and sometimes a 9" for free!
| Quote: | | So to prove a point about low bandwidth 8" projectors being able to handle higher scan rates and vertical rates is not something that going to happen when your goal is to resolve the image and not just display it. |
Mike, that makes no sense at all. As you should know, the scan rate capability of 8" Marquee's is exactly the same as the 9".
And, BTW, scan rate is not the same as resolution!!! They are different!!!
Bob
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VideoGrabber
Joined: 09 Apr 2006
Posts: 933
Location: Michigan
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| Posted: Tue May 29, 2012 5:05 pm Post subject: |
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Boilermaker wrote:
> Point well made. I see two reasons why a good 8" machine would struggle with this rate... while 1600 lines using the full tube is roughly equivalent... I do not recommend it. <
Thanks!
> As I have stated in previous posts, <
I will have to apologize here, for not having read them all. I'm still trying to catch up a bit from my 10-month vacation from the CPF.
> I run 1200 lines (800 from my DVDO VP50 and then scale to 1200 with my blend boxes). If I had a pair of 9" projectors, I would take it to 1600. <
Thanks again, Bob. You're basically doing what I would expect, and would do myself. Makes good sense. I have no problem accepting 1200p on 8" PJs (~90 kHz scanrate), or 1600p on 9-inchers. I appreciate the clarification.
_________________
- Tim
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mp20748
Joined: 12 Sep 2006
Posts: 5689
Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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| Posted: Tue May 29, 2012 5:31 pm Post subject: |
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| Boilermaker wrote: |
| Quote: | | So to prove a point about low bandwidth 8" projectors being able to handle higher scan rates and vertical rates is not something that going to happen when your goal is to resolve the image and not just display it. |
Mike, that makes no sense at all. As you should know, the scan rate capability of 8" Marquee's is exactly the same as the 9".
And, BTW, scan rate is not the same as resolution!!! They are different!!!
Bob |
Yeah, but how did you misunderstand this when my discussions was dealing with bandwidth, resolution and scan rate. And since bandwidth is determined by the scan rate (this is why it was mentioned). And if the scan rate and bandwidth don't match... guess what, nor will the resolution.
So to be clear here, my discussions were about resolution capability, and as also previously mentioned by me (above):
"when your goal is to resolve the image and not just display it".
The goal is always to resolve the image. And in doing that you must make sure that bandwidth and scan rate are also considered.
Your NEC can display 1080P, but it can't resolve 1080P. And the reason why it won't resolve 1080P has to do with the scan rate and bandwidth capability of your NEC not agreeing with each other.
Last edited by mp20748 on Tue May 29, 2012 5:37 pm; edited 1 time in total
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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Boilermaker
Joined: 21 May 2006
Posts: 527
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| Posted: Tue May 29, 2012 5:36 pm Post subject: |
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| Quote: | | And the reason why it won't resolve 1080P has to do with the scan rate and bandwidth not agreeing with each other |
And this is proof that you don't understand what either of these two are!
Bob
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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mp20748
Joined: 12 Sep 2006
Posts: 5689
Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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| Posted: Tue May 29, 2012 5:42 pm Post subject: |
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| Nashou66 wrote: | But his blended NEC's will resolve 1080p and more.
Sent from iPhone
Nashou |
Yeah, and technically it will do it 100%. And being able to 100% resolve 1080P, it should produce a very sharp and crystal clear image.....but you and I both know that's not the case.
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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| Posted: Tue May 29, 2012 5:47 pm Post subject: |
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| mp20748 wrote: | | Nashou66 wrote: | But his blended NEC's will resolve 1080p and more.
Sent from iPhone
Nashou |
Yeah, and technically it will do it 100%. And being able to 100% resolve 1080P, it should produce a very sharp and crystal clear image.....but you and I both know that's not the case. |
You are serious aren't you?!?
Oh boy!!
Nashou
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mp20748
Joined: 12 Sep 2006
Posts: 5689
Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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| Posted: Tue May 29, 2012 5:52 pm Post subject: |
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| Boilermaker wrote: | | Quote: | | And the reason why it won't resolve 1080P has to do with the scan rate and bandwidth not agreeing with each other |
And this is proof that you don't understand what either of these two are!
Bob |
Really!
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mp20748
Joined: 12 Sep 2006
Posts: 5689
Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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| Posted: Wed May 30, 2012 1:58 am Post subject: |
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| VideoGrabber wrote: | Boilermaker wrote:
> Point well made. I see two reasons why a good 8" machine would struggle with this rate... while 1600 lines using the full tube is roughly equivalent... I do not recommend it. <
Thanks!
> As I have stated in previous posts, <
I will have to apologize here, for not having read them all. I'm still trying to catch up a bit from my 10-month vacation from the CPF.
> I run 1200 lines (800 from my DVDO VP50 and then scale to 1200 with my blend boxes). If I had a pair of 9" projectors, I would take it to 1600. <
Thanks again, Bob. You're basically doing what I would expect, and would do myself. Makes good sense. I have no problem accepting 1200p on 8" PJs (~90 kHz scanrate), or 1600p on 9-inchers. I appreciate the clarification. |
We'll get back to this tomorrow, and will then show why this is all wrong..
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dvh99
Joined: 25 Dec 2009
Posts: 2158
Location: nederland
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| Posted: Wed May 30, 2012 2:25 am Post subject: |
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and there i thought a crt could never produce an exact square wave (without some rise and fall time no matter how tweaked) so 100% resolving 1080p is never the case let alone resolving it with the limitations optically and a perfect astig.
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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