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cmjohnson
Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s
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| Posted: Mon Feb 15, 2016 2:41 am Post subject: Marquee, lowest tolerable scan rate? |
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What, in your opinion, is the lowest tolerable (progressive) scan rate on a Marquee?
At what point does flicker become objectionable to you?
The reason I'm asking is to try to figure out the minimum bandwidth required for higher than 1080P resolutions.
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gjaky
Joined: 05 Jun 2010
Posts: 2802
Location: Budapest, Hungary
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| Posted: Mon Feb 15, 2016 6:49 am Post subject: |
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Go interlaced, there was a thread about this by noos@xp37+
_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB, VIM-DB
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barclay66
Joined: 27 Jun 2011
Posts: 1304
Location: Germany
TV/Projector: Marquee 9500 Ultra
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| Posted: Mon Feb 15, 2016 8:14 am Post subject: |
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Hi,
As I see it, the sensitivity to flicker is different from person to person.
Maybe You should collect opinions from several people using a standardized scheme.
So You would be able to create some statistics. Here's an example using my tolerance levels:
Resolution - Flicker
>70p - Invisible
70p - Invisible
60p - Noticeable
50p - Tolerable
48p - Tolerable
30p - Annoying
<30p - Annoying
Key:
Invisible - No flicker percepted, perfect
Noticeable - Some flicker in peripheral areas, still good
Tolerable - Flicker visible when focusing on it, still OK
Annoying - Predominance of flicker makes it unwatchable
Regards,
barclay66
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tschaeikaei
Joined: 08 Apr 2013
Posts: 490
Location: Germany/Saarland
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| Posted: Mon Feb 15, 2016 8:51 am Post subject: |
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Good morning,
interesting you notice flicker at 60Hz. I think you talk about your Marquee using a P22 HKA green.
I always thought my fast P43 green makes me see flicker at 60Hz and i don't notice anything at 72Hz. Never tried 70Hz.
I think many people run their projectors at 60Hz. So do you think you are very sensitive to flicker?
By the way i never noticed flicker on my 9PG on 60Hz, but i did not watch out for it.
If i would try 4k interlaced today, i would maybe start with 48Hz. Barclay and i would surely not like it, but may be that you are less sensitive.
But even if you have to go up all the way to 96i (to avoid motion blur), you'd still end up with a
bandwidth equal to 48p.
So, yes i think interlaced is the way to go. There is a thread where two people fought each other with some numbers about 4k bandwidth (and pixel clock  ).
Changed U17 and U20, now beeing about to try if the board does it again. Would have been more elegant to measure voltages and waveforms
while running, but no chance to reach the location. I knew troubleshooting would be a pain in the ass when the pj is on the ceiling.
Regards, Julian
_________________
Marquee 9500U edgeblend P43 | NEC 9PG
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barclay66
Joined: 27 Jun 2011
Posts: 1304
Location: Germany
TV/Projector: Marquee 9500 Ultra
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| Posted: Mon Feb 15, 2016 2:00 pm Post subject: |
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| tschaeikaei wrote: | Good morning,
interesting you notice flicker at 60Hz. I think you talk about your Marquee using a P22 HKA green.
I always thought my fast P43 green makes me see flicker at 60Hz and i don't notice anything at 72Hz. Never tried 70Hz.
I think many people run their projectors at 60Hz. So do you think you are very sensitive to flicker? |
Hi,
For watching I only use conventional LCPs at the moment but I'm sure that a faster phosphor would make flicker much more noticeable. Still I can make it out at 60p if I look at the center of the screen and at the same time concentrate on its edge. This is what wikipedia has to say about it:
"The exact refresh rate necessary to prevent the perception of flicker varies greatly based on the viewing environment. In a completely dark room, a sufficiently dim display can run as low as 30 Hz without visible flicker. At normal room and TV brightness this same display rate would produce flicker so severe as to be unwatchable.
Chewing something crunchy such as Doritos or granola can induce flicker perception due to the vibrations from chewing synchronizing with the flicker rate of the display.
Another factor in detecting flicker is peripheral vision. The human eye is most sensitive to flicker at the edges of human field of view, and least sensitive at the center of gaze (the area being focused on). As a result, the greater the portion of our field of view that is occupied by a display, the greater is the need for high refresh rates. This is why computer monitor CRTs usually run at 70 to 90 Hz, while TVs, which are viewed from further away, are seen as acceptable at 60 or 50 Hz."
The different behaviour of the peripheral vision is part of our evolutionary process. When living in the wild it was an advantage to be able to notice even small and fast movements at the edges of the field of view as those could represent a threat...
Regards,
barclay66
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gjaky
Joined: 05 Jun 2010
Posts: 2802
Location: Budapest, Hungary
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cmjohnson
Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s
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| Posted: Mon Feb 15, 2016 10:12 pm Post subject: |
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For the moment I'm going to set 48 Hz as the absolute minimum requirement, in the long-shot hopes that there might be some way to get 4K running on my Marquee after suitable mods. (Which include a phenomenally rare set of special tubes made for the HR project, which are designed to be sharper than LUGs but have a slower phosphor like LCPs, apparently.)
Even if I don't get FULL 4K, then I am at least hoping for downsampled 4K giving me something between 4K and 2K. Maybe 3, or 3.5K might at least be possible.
The tough part will be finding a way to get the HDMI 2.0 signal to cough up an RGB signal. Without that, this egg will never hatch.
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Spanky Ham
Joined: 22 Mar 2006
Posts: 5643
Location: Comedy Central
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| Posted: Tue Feb 16, 2016 1:49 am Post subject: |
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Good idea barclay about standard.
Chris Stephens recommends using the lowest refresh rate you can tolerate for the best image.
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