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garyfritz
Joined: 08 Apr 2006 Posts: 12026 Location: Fort Collins, CO
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Link Posted: Mon May 12, 2008 6:53 pm Post subject: |
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Well, they measured the DW with a spectrophotometer or something close to that, so I assumed the results were reasonably accurate.
My screen is 85x48, or 28.33 sq ft. The 8500s are rated 225 ANSI lumens. 225 lumens / 28.33 sq ft = 7.94 ftL at 1.0 gain. If my BOC has a gain of 0.85, that says I'd read 6.75 ftL, or 7.14 ftL if the BOC is 0.9. I'm reading 7.0, right in that area.
When displaying a window pattern I would expect more than the ANSI rating, ...?
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Person99
Joined: 09 Mar 2006 Posts: 4901 Location: Flower Mound, TX
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Link Posted: Mon May 12, 2008 7:32 pm Post subject: |
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garyfritz wrote: | Well, they measured the DW with a spectrophotometer or something close to that, so I assumed the results were reasonably accurate. |
I'd never seen a true professional measurement of it. Do you have a link handy?
garyfritz wrote: | My screen is 85x48, or 28.33 sq ft. The 8500s are rated 225 ANSI lumens. 225 lumens / 28.33 sq ft = 7.94 ftL at 1.0 gain. If my BOC has a gain of 0.85, that says I'd read 6.75 ftL, or 7.14 ftL if the BOC is 0.9. I'm reading 7.0, right in that area.
When displaying a window pattern I would expect more than the ANSI rating, ...? |
Actually yeah, a 10% window should be closer to your peak lumen rating than your ANSI lumen rating. But, if you are watching Ice Age, you'll get closer to the ANSI lumen rating.
_________________ Dave
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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garyfritz
Joined: 08 Apr 2006 Posts: 12026 Location: Fort Collins, CO
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Link Posted: Mon May 12, 2008 8:45 pm Post subject: |
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Person99 wrote: | I'd never seen a true professional measurement of it. Do you have a link handy? |
Well, it used to be at http://www.avsforum.com/avs-vb/showthread.php?p=8380263&&#post8380263 -- but all the charts and graphs he posted are missing now. Clarence reformatted the gain data in the next response, which shows the DW has a gain of 1.24 on-axis. Post 226 in that thread lists the equipment they used.
Quote: | Actually yeah, a 10% window should be closer to your peak lumen rating than your ANSI lumen rating. |
And an 8500 has a peak rating of about 1200 lumens, meaning I should be able to see upwards of 7*1200/225=37 ftL on my 10% window!? Not bloody likely...
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garyfritz
Joined: 08 Apr 2006 Posts: 12026 Location: Fort Collins, CO
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Link Posted: Wed May 14, 2008 7:27 pm Post subject: |
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Well this is very interesting. I've always used my SpyderII with the filter OFF, because I was told that was the right way to use it with front projectors. And when I first tested it, that seemed to be true.
But I just dug out the filter and tried it again, comparing it against my Minolta TV2150 colorimeter. I warmed up the projector and both colorimeters for 30 minutes, then ran a grayscale on both of them, both in the same position (about 1' from the screen). I used the 2000 "msec" read time that Kal recommends for the Spyder.
And guess what -- the Spyder looks just fine. If anything it looks better than the Minolta! E.g. the Spyder has more sensible-looking readings at 10-20IRE, which makes sense, since that's below the Minolta's rated range. (Probably below the Spyder's too, but the long exposure probably helps that.) Also, at 100IRE the Spyder shows 10.3 ftL, vs. 6.8 for the Minolta. The lumen calcs above say 7 ftL could be reasonable, but I don't think my screen is THAT dark. An 8500 should be able to throw a lot more than 7 ftL onto an 85" wide screen. I wish I had a known-good standard to compare against...
The pics below show the differences -- Spyder on top, Minolta on bottom. The Spyder doesn't show as much red "hump" as the Minolta -- which makes sense to me, I didn't understand why I'd have a hump in red -- though it indicates I should boost the red Drive a little. The Spyder says my low gamma is a bit low, meaning my luminance is too high there. Guess I should back off on the Moome boost a bit.
So I guess I don't need to throw away my Spyder after all!
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kal Forum Administrator
Joined: 06 Mar 2006 Posts: 17860 Location: Ottawa, Canada
TV/Projector: JVC DLA-NZ7
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GEBrown
Joined: 08 Mar 2006 Posts: 729 Location: Denver
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Link Posted: Thu May 15, 2008 5:58 pm Post subject: |
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Gary said: "So I guess I don't need to throw away my Spyder after all!"
Gary, that's what I hate about this stuff. You have two meters, two readings, and no real way of knowing which is closer to "right". If you do final tweaks to your image with one colorimeter, the other will likely tell you the results are way off spec and vice versa.
Seems like we still need to depend on our eyes as to which is more pleasing and just go with that.
_________________ Member of the Marquee Maniacs Club
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garyfritz
Joined: 08 Apr 2006 Posts: 12026 Location: Fort Collins, CO
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Link Posted: Thu May 15, 2008 6:24 pm Post subject: |
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Well, the fact that the two meters agree very closely (except for ftL levels) is good enough for me. The Minolta is nice for setting grayscale at 30/80% because it reads much faster than the Spyder -- but it doesn't quite agree at 80%. The Spyder is nice for reading the full grayscale since it reads more accurately at low IREs and you don't have to type the numbers in by hand. But it is slooow for setting grayscale.
Since the Spyder (with the filter on) seems to be at least as accurate as the Minolta, I think I'll probably sell the Minolta.
And yes, your eyes are the final judge. But getting something that looks good to your eyes can be mighty difficult if you're doing it by the seat of your pants. Think e.g. of the pic of Jennifer Aniston on Clarence's G90 before & after Terry calibrated it. He thought it looked pretty good beforehand, but it was dramatically better once it was set right. That "getting it set right" really needs calibration tools, unless you've got an incredibly good eye for setting D65.
Plus it's a fun toy to play with.
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kal Forum Administrator
Joined: 06 Mar 2006 Posts: 17860 Location: Ottawa, Canada
TV/Projector: JVC DLA-NZ7
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garyfritz
Joined: 08 Apr 2006 Posts: 12026 Location: Fort Collins, CO
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Link Posted: Thu May 15, 2008 8:22 pm Post subject: |
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A little bitter are we??
Seriously, if you compare my Spyder and Minolta results, you'll see 1) they're close enough that I believe the Spyder is pretty accurate, and 2) it appears to me the Spyder is the more accurate of the two. So the Spyder isn't ALWAYS a POS.
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SYC
Joined: 16 May 2006 Posts: 269
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Link Posted: Wed May 28, 2008 4:13 am Post subject: |
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I own two spyder2 sensors. The inter-sensor accuracy sucks though it has good repeatability and it can get better result than eyes' calibration. Maybe Gary's is the lucky one. But it seems to be a good way to use the correction matrix in HCFR to calibrate Spyer2 because of its good repeatability if you can borrow a preciser meter to do it.
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karmat63
Joined: 19 Dec 2007 Posts: 157 Location: Italy
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Link Posted: Sat Oct 18, 2008 4:48 am Post subject: |
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garyfritz wrote: | No, sharp is at 50, I started out at 47, and I ended up at 59. 9 off is pretty significant for a Marquee. |
Maybe I'm wrong, but I think you're overfocusing passing from 50 to 59, isn't it?
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SYC
Joined: 16 May 2006 Posts: 269
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Link Posted: Mon Jan 05, 2009 9:15 pm Post subject: |
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garyfritz wrote: | I have my Minolta sensor about 4" from the screen. My BOC probably has a gain of 0.9 or so. DW is 1.24, so the higher gain would only bump the reading up to 7.0*1.24/0.9 = 9.6 ftL.
I suspect the Minolta's ftL measurement is off. But could that be off if the color measurement is right (which it seems to be)? Seems unlikely, but... |
I compared the readings between Sencore ColorPro II and Spyder2 for my XG110 months ago. If I remember right, the luminance reading of Spyder2 is almost twice than ColorPro II. The ColorPro II's reading is close to your Minolta's reading, so I believe Spyder is off far away. By the way, my friend's Sypder2 have a close reading with my Spyder2, so I believe is a big problem of Spyder2 and I give it up.
SYC
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