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Elaine Benes
Joined: 25 Apr 2006
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Nashou66
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CRT_Ben
Joined: 28 Aug 2006
Posts: 1684
Location: Northern Virginia
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| Posted: Tue Feb 12, 2008 2:29 pm Post subject: |
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I'm skimming through it...good lord, the setup must have been TERRIBLE! The document says that an Electrohome rep set up the machine, but they list ANSI checkerboard contrast as low as 98:1 and full on/off contrast as 11.6fL/5mfL = 2320:1! What the hell, that's terrible LCD territory.
Last edited by CRT_Ben on Tue Feb 12, 2008 3:36 pm; edited 1 time in total
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Clarence
Joined: 08 Mar 2006
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Location: Smith Mtn Lake, VA
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| Posted: Tue Feb 12, 2008 3:18 pm Post subject: |
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Great document.
I've seen Ken do these measurements and the results are always interesting.
But it's hard to put any of the test measurements into perspective unless you compare them to something else... e.g. before and after calibration or compared to another projector.
Notice how the black squares measure worse in correlation with the number of surrounding white squares. Logical.
I'll have to read to see if the room had dark walls. Looks like there might've been a lot of reflected light off that 1.3 gain screen ruining the black levels.
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CRT_Ben
Joined: 28 Aug 2006
Posts: 1684
Location: Northern Virginia
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| Posted: Tue Feb 12, 2008 3:35 pm Post subject: |
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Oops, I misread the MTF table for resolution. Okay, they list MTF as about 18% in the center at 1280x1024, that sounds better.
Still, I'm curious, if I get some time tonight I'll do some measurements of my own. My screen is a hi-power, though, so not exactly uniform...
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Clarence
Joined: 08 Mar 2006
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Location: Smith Mtn Lake, VA
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| Posted: Tue Feb 12, 2008 3:40 pm Post subject: |
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Interesting... I would've measured the halo in the opposite manner. I always think of the green square generated by the ACON. On a air-coupled 8000/8111/8501, the green ACON square clearly creates a soft halo. But on the 9501LC, the halo around the ACON square is much improved.
But maybe it's more complicated to measure on the outside of a square, because then you'd have to decribe parameters for halo effect from a given distance from the lit square.
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Robert A. Hill
Joined: 19 May 2006
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Location: Simpsonville, SC
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Clarence
Joined: 08 Mar 2006
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Location: Smith Mtn Lake, VA
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| Posted: Tue Feb 12, 2008 6:10 pm Post subject: |
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Those extra lumens at the high-IRE offset the poorer black levels...
black gives 0.37FL from the lightvalve 
black=0.005 from the M9501.
Check out how much light output comes from green...
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CRT_Ben
Joined: 28 Aug 2006
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Location: Northern Virginia
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| Posted: Tue Feb 12, 2008 6:22 pm Post subject: |
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Sweet - now we know why CRT ROCKS for smooth, natural looking motion!!
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Clarence
Joined: 08 Mar 2006
Posts: 3827
Location: Smith Mtn Lake, VA
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| Posted: Tue Feb 12, 2008 6:40 pm Post subject: |
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| Clarence wrote: | Those extra lumens at the high-IRE offset the poorer black levels...
black gives 0.37FL from the lightvalve
black=0.005 from the M9501 |
I just noticed that 0 IRE ("black") from the lightvalve (0.3746FL) is brighter than everything below ~35 IRE from the M9501. 
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ecrabb
Forum Moderator
Joined: 13 Mar 2006
Posts: 15909
Location: Utah
TV/Projector: JVC RS40, Epson 5010
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| Posted: Tue Feb 12, 2008 7:27 pm Post subject: |
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Wow, that is some fascinating stuff. Very cool info. God, I'm such a geek.
SC
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Person99
Joined: 09 Mar 2006
Posts: 4899
Location: Flower Mound, TX
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| Posted: Tue Feb 12, 2008 7:44 pm Post subject: |
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| CRT_Ben wrote: | | I'm skimming through it...good lord, the setup must have been TERRIBLE! The document says that an Electrohome rep set up the machine, but they list ANSI checkerboard contrast as low as 98:1 and full on/off contrast as 11.6fL/5mfL = 2320:1! What the hell, that's terrible LCD territory. |
This is not surprising. A CRT is pretty bad at ANSI contrast. It was almost 150:1 at a lower resolution and that is about what you would expect from an LC machine. Thankfully, ANSI contrast doesn't matter that much. 
Everybody here thinks they have great on/off CR. They don't. The average CRT owner is either crushing blacks or has an on/off CR below 5000:1 (much less depending upon how it is tested). I don't think a stock marquee can achieve much better than 3500:1 without crushing blacks.
Also, part of our phenomenal on/off numbers are based upon the super high output of a 10% window. With a 100% full white screen the PJ has to limit the current and the light output is much less. If I had to guess, I would have said the on/off of a stock marquee measured with a full white screen and no black crush was about 1800:1--so these numbers are better than I expected!
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A train station is where the train stops. A bus station is where the bus stops. On my desk, I have a work station....
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CRT_Ben
Joined: 28 Aug 2006
Posts: 1684
Location: Northern Virginia
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| Posted: Tue Feb 12, 2008 8:07 pm Post subject: |
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So, Dave, if our CRTs apparently don't have inky blacks and certainly don't have blinding whites, why do they look so much better and seem to have more dynamic range than POS LCDs?
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kschmit2
Joined: 09 Mar 2006
Posts: 1141
Location: Heidelberg, Germany
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| Posted: Tue Feb 12, 2008 8:53 pm Post subject: |
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The issue with on/off in that test was lack of light reading capability at very low light levels. The lowest reading possible with the equipment used in the testing was 5 mfL, so they just took that number.
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Person99
Joined: 09 Mar 2006
Posts: 4899
Location: Flower Mound, TX
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| Posted: Tue Feb 12, 2008 9:20 pm Post subject: |
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| CRT_Ben wrote: | | So, Dave, if our CRTs apparently don't have inky blacks and certainly don't have blinding whites, why do they look so much better and seem to have more dynamic range than POS LCDs? |
1) CRTs do not have inky blacks on mixed scenes like an ANSI checkboard. But it does not matter. A dark gray dot on a black field looks dark grey. A dark grey dot on a light field looks black. Clarence has posted numerous images that show this. A viewer cannot tell the difference on normal content between a 100:1 and a 400:1 ANSI CR display. This is why the biggest weakness of the CRT does not matter in normal viewing.
2) With regard to on/off, Marquees are pretty bad stock about crushing blacks, so with a stock marquee you either have elevated black levels or crushed blacks. If you want to see all the shadow detail, you are going to have your brighness cranked way up.
3) We can have close to blinding whites if the APL is not super high. Most movie content is closer to the APL of a 10 or 20% window than a full white screen, so the CRT is plenty bright. In fact, on most real movie content, I find my CRT to be brighter than many popular digitals.
4) With gamma correction and proper set up, I think most good CRT PJs may hit over 12,000:1 in a good room and should easily achieve 8000:1. I don't think most people are getting close to that without crushing blacks on their CRTs.
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A train station is where the train stops. A bus station is where the bus stops. On my desk, I have a work station....
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