Contrast ratio results

Contrast ratio 861:1
Monitor model
Submitted 18 Apr 2009 02:00 CEST, by 24.255.*.*
Camera model Canon PowerShot A470
Processing remarks

Warning: image file 1: automatic white balance can cause inaccuracies.
image file 1: Note: image seems to be noisy. Try reducing the ISO setting or increasing the exposure time.
Warning: image file 1: Underexposed. Please increase the shutter time.
Note: image file 1: suggested exposure time: 7.5 s (Set EV to +1.9)
Warning: image file 2: automatic white balance can cause inaccuracies.
Warning: image file 2: Underexposed. Please increase the shutter time.
Note: image file 2: suggested exposure time: 1/29 s (Set EV to -0.2)
Warning: Image ISO settings are not the same.

Black
Screen photo
Luminance 0.06 cd/m2
Luminance spread 0.03 cd/m2 (2 standard deviations)
Exposure value –6.41 stops   (aim for –2 to –3)
Exposure spread 0.66 stops
Area used for calculation 0.542 x 0.542
Camera settings Exposure time: 0.5   ISO: 320   F-number: 3
Focal length: 37.5 mm   (35 mm equivalent)
Exposure compensation: -2
White
Screen photo
Luminance 49 cd/m2
Luminance spread 4 cd/m2 (2 standard deviations)
Exposure value –4.32 stops   (aim for –2 to –3)
Exposure spread 0.13 stops
Area used for calculation 0.542 x 0.542
Camera settings Exposure time: 1/101   ISO: 80   F-number: 3
Focal length: 37.5 mm   (35 mm equivalent)
Exposure compensation: -2

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.