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Discussion Starter · #1 ·
Are the Minolta CL-200 and CL-100 suitable for setting greyscale on CRT-projectors?


Gunnar
 

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Most of the time I use a CL-200 to calibrate my XG1100. It works great at the higher IRE levels but isn't sensitive enough at low levels. I usually end up having to place the meter about 1/3 the distance between projector and screen to get a bright enough signal for the meter to give reliable Cx and Cy values.


The thing that bothers me about that is that red. green and blue light received by the meter comes from different angles because of RGB tube placement. The closer to the projector the steeper the angle from red and blue. This means you are becoming more dependent on the accuracy of CL-200's cosine correction capability to get accurate measurements.
 

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Discussion Starter · #4 ·
Thanks!

I think both meters have about the same sensitivity.


Tibia, What do you mean by low levels? 20 IRE? My room has dark colors, and no windows, so it can be made almost completely dark. I guess this is important, though I`m a complete newbie on greyscale calibrating.


Gunnar
 

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Gunnar,


According to CL-200 specifications 5 lux is the lower limit for reliable Cx and Cy measurements. Correlating 5 lux to some IRE level is not possible unless you specify some distance between the meter and projector. At the screen 5 lux will be measured at a higher IRE level than if the meter were closer to the projector where a lower IRE will still measure 5 lux.


In my case I can't go below 30 IRE before the CL-200 displays starts to blink. That is holding the meter about 4 feet from the projector. My projector to screen distance is about 13 feet. My screen is 10 feet wide. My room isn't as dark as yours so everything at the bottom end is pretty iffy for me.
 

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Quote:
Originally Posted by tibia
In my case I can't go below 30 IRE before the CL-200 displays starts to blink. That is holding the meter about 4 feet from the projector.
I would guess that 30ire 4 feet from most PJs would be uncomfortable to look at directly with the naked eye. I've always wondered why it's apparently so difficult and expensive to make a sensor that can read 20ire, which is really not that dim.
 
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