Projector Calibration - AVS Forum
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post #1 of 9 Old 08-22-2010, 07:43 AM - Thread Starter
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Ok... First time ever trying to calibrate the projector. I am having a hell of a time of getting the temp reading. The reading will go the frequency of the chart, below the scale off the scale. It all depends where the meter is, thus how do I know what reading will be correct? Anyone have any pic they can share of the meter position when calibrating a projector?

Thanks!
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post #2 of 9 Old 08-22-2010, 11:13 AM
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read this Thread,

http://www.curtpalme.com/forum/viewtopic.php?t=10457

Athanasios
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post #3 of 9 Old 08-23-2010, 02:42 AM
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The type of meter you use dictates where it should (or can) be placed. Some meters can't be used to take readings off the screen, they have to be aimed at the lens of the projector... which is not ideal. The screen is an integral part of the imaging system and should be included in the calibration meter readings.

In general, the meter should be on the same axis as the viewer's eyes so it "sees" the screen from the same angle as the viewer. And some types of meters need to be some distance from a screen so they measure enough pixels to get a "solid" reading. Some meters get very few pixels when they are placed too close to the screen. So... how you measure a screen/projector combo is very much dependent on your meter.

"Movies is magic..." Van Dyke Parks
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post #4 of 9 Old 08-23-2010, 09:44 AM
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Quote:
Originally Posted by Doug Blackburn View Post

The type of meter you use dictates where it should (or can) be placed. Some meters can't be used to take readings off the screen, they have to be aimed at the lens of the projector... which is not ideal. ....

So... how you measure a screen/projector combo is very much dependent on your meter.

Just for future reference, if one were to be calibrating a DLP PJ with a colorimeter (Display2 or Chroma5,) would one use a direct screen measurment or would a screen offset + lens measure be a more accurate way to go? Specifically, I would be concerned about getting enough light off the screen at low %stim/IRE levels to get an accurate reading.
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post #5 of 9 Old 08-23-2010, 11:54 AM
 
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Often it can be useful to use both to measure the lower percentages out of the lens rather than off the screen. You can measure higher values using both methods to calculate an offset if necessary, then use that to figure the low % that you can't measure off the screen reliably.
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post #6 of 9 Old 08-23-2010, 10:47 PM
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^^^ Makes sense. My calibration experience is limited to CRTs (direct view and RPTV,) so I suppose there's going to be a bit of a learning curve if/when I take the plunge.
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post #7 of 9 Old 08-28-2010, 01:47 AM
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Quote:
Originally Posted by ChrisWiggles View Post

Often it can be useful to use both to measure the lower percentages out of the lens rather than off the screen. You can measure higher values using both methods to calculate an offset if necessary, then use that to figure the low % that you can't measure off the screen reliably.

Chris.. This always puzzled me. Why do you need to calculate an offset, which is based off measuring directly off the lens anyway? Why don't you just measure this directly off the lens even in low%? What's the advantage of creating an offset compared to measuring directly off the lens?
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post #8 of 9 Old 08-28-2010, 03:20 AM
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Quote:
Originally Posted by fight4yu View Post

Chris.. This always puzzled me. Why do you need to calculate an offset, which is based off measuring directly off the lens anyway? Why don't you just measure this directly off the lens even in low%? What's the advantage of creating an offset compared to measuring directly off the lens?

Your screen is a color.
It absorbs some light better than other.

The light you see is the reflected light from the screen.
Your eye does not watch the movie on the lens.

Although you could create the offset then do all the measurements from the lens.

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post #9 of 9 Old 08-28-2010, 11:07 AM
 
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Quote:
Originally Posted by fight4yu View Post

Chris.. This always puzzled me. Why do you need to calculate an offset, which is based off measuring directly off the lens anyway? Why don't you just measure this directly off the lens even in low%? What's the advantage of creating an offset compared to measuring directly off the lens?

As sotti points out the screen impacts color.

And also there can be some methodology issues in measuring off the lens depending on your meter.
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