Contrast ratio of IBM Thinkpad T23 (1024x768)

Contrast ratio 139:1 (edge: 168:1)
Monitor model IBM Thinkpad T23 (1024x768)
Submitted 04 Mar 2008 19:12 CET, by 82.139.*.*
Camera model Canon PowerShot A540
Processing remarks

Note: image file 2: suggested exposure time: 1/430 s (Set EV to +0.6)

Black
Screen photo
Luminance 0.79 cd/m2
Luminance spread 1.31 cd/m2 (2 standard deviations)
Exposure value –2.88 stops   (aim for –2 to –3)
Exposure spread 3.46 stops
Area used for calculation 0.495 x 0.495
Camera settings Exposure time: 1/4   ISO: 400   F-number: 2.6
Focal length: 34.3 mm   (35 mm equivalent)
Exposure compensation: 2
White
Screen photo
Luminance 109 cd/m2
Luminance spread 15 cd/m2 (2 standard deviations)
Exposure value –1.07 stops   (aim for –2 to –3)
Exposure spread 0.2 stops
Area used for calculation 0.495 x 0.495
Camera settings Exposure time: 1/159   ISO: 400   F-number: 2.6
Focal length: 34.3 mm   (35 mm equivalent)
Exposure compensation: 2
Black at screen edge
Screen photo
Luminance 0.65 cd/m2
Luminance spread 1.1 cd/m2 (2 standard deviations)
Exposure value –2.89 stops   (aim for –2 to –3)
Exposure spread 3.6 stops
Area used for calculation 0.495 x 0.495
Camera settings Exposure time: 0.3   ISO: 400   F-number: 2.6
Focal length: 34.3 mm   (35 mm equivalent)
Exposure compensation: 2
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The luminance values in cd/m2 are not very reliable, since camera sensitivities can easily differ up to 50% from their nominal value. Typically, the real luminance is 30% lower than this number. The area used for calculation is chosen such that it corresponds to a viewing angle of ±14° horizontally and ±10.5° vertically, which is equivalent to viewing the screen from a distance of about 1.5 times the diagonal size.

Unfortunately, there is a lot of variation in how cameras use EXIF settings. If photos from your camera your produce unusable results, try coming back in a few days. I review submitted pictures regularly and try to fix problems.