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Contrast ratio results for IBM Thinkpad T23 (1024x768)

Contrast ratio 161:1 (edge: 289:1)
Monitor model IBM Thinkpad T23 (1024x768)
Submitted 04 Mar 2008 19:08 CET, by 82.139.*.*
Camera model Canon PowerShot A540
Processing remarks

Note: image file 1: suggested exposure time: 0.4 s (Set EV to +1.3)
Warning: image file 3: Underexposed. Please increase the shutter time.
Note: image file 3: suggested exposure time: 0.7 s (Set EV to +1.5)

Black
Screen photo
[open image]
Luminance 0.64 cd/m2
Luminance spread 1.19 cd/m2 (2 standard deviations)
Exposure value –3.76 stops   (aim for –2 to –3)
Exposure spread 4.25 stops
Area used for calculation 0.495 x 0.495
Camera settings Exposure time: 1/6   ISO: 400   F-number: 2.6
Focal length: 34.3 mm   (35 mm equivalent)
Exposure compensation: 0
White
Screen photo
[open image]
Luminance 103 cd/m2
Luminance spread 18 cd/m2 (2 standard deviations)
Exposure value –1.81 stops   (aim for –2 to –3)
Exposure spread 0.25 stops
Area used for calculation 0.495 x 0.495
Camera settings Exposure time: 1/251   ISO: 400   F-number: 2.6
Focal length: 34.3 mm   (35 mm equivalent)
Exposure compensation: 0
Black at screen edge
Screen photo
[open image]
Luminance 0.36 cd/m2
Luminance spread 0.52 cd/m2 (2 standard deviations)
Exposure value –4.02 stops   (aim for –2 to –3)
Exposure spread 2.7 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: 0

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.