Very low value foot lambert in non-dedicated room - AVS Forum
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post #1 of 6 Old 03-30-2012, 01:48 AM - Thread Starter
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Hello friends.

Let them the following question:

I only managed to obtain a value of 100% IRE white of 8 foot lambert

Why I can not get a higher value to calibrate my projector?

Could it be because the walls and ceiling of my room are white?

In black Batcave could increase this value to 12 or 16 foot lambert

Thank you very much
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post #2 of 6 Old 03-30-2012, 04:31 AM
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Your room conditions aren't going to change the light coming from your projector. If the lights are off and you are only getting 8 foot lamberts on your screen, that is the most you are going to get.

Turning on the lights or white walls/ceiling might raise your foot lamberts as more light is hitting the screen but that is not the light you want. The white walls or ambient light is what hurts ANSI contrast. A bat cave will not raise the foot lamberts but will help ANSI contrast.

Are you using a 100ire window or field pattern for the measurement? It should be a field for this measurement. That can cause a bit of a discrepenancy, depending on the meter you are using.

How big is your screen? What gain? What projector?
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post #3 of 6 Old 03-30-2012, 04:52 AM
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Put your read on continuous and change the meter's aim at the center of the screen until you get the maximum light measurement. Calibrate from there.

The difference in aiming points can be huge.

Buzz
THX Certified Video Calibrator

 

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post #4 of 6 Old 03-30-2012, 05:30 AM
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what tool are you using for measuring?

President, Lion Audio Video Consultants Inc.
Lead THX Video Standards Instructor
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post #5 of 6 Old 03-30-2012, 06:08 AM - Thread Starter
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Quote:
Originally Posted by BobL View Post

Your room conditions aren't going to change the light coming from your projector. If the lights are off and you are only getting 8 foot lamberts on your screen, that is the most you are going to get.

Turning on the lights or white walls/ceiling might raise your foot lamberts as more light is hitting the screen but that is not the light you want. The white walls or ambient light is what hurts ANSI contrast. A bat cave will not raise the foot lamberts but will help ANSI contrast.

Are you using a 100ire window or field pattern for the measurement? It should be a field for this measurement. That can cause a bit of a discrepenancy, depending on the meter you are using.

How big is your screen? What gain? What projector?

Hello

I used a pattern for measurement window 100% white.

Screen 106 ", gain 1.1 and Optoma DLP HD80

Thank you very much.
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post #6 of 6 Old 03-30-2012, 06:13 AM - Thread Starter
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Quote:
Originally Posted by Gregg Loewen View Post

what tool are you using for measuring?

Hello

I use CromaPure and eye one display 2

It is clear that my views are not correct.

Thank you very much
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