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Contrast ratio of Canon PowerShot A40

Contrast ratio 793:1
Monitor model Canon PowerShot A40
Submitted 21 Mar 2008 08:51 CET, by 75.164.*.*
Camera model Canon PowerShot A40
Processing remarks


Black
Screen photo
[open image]
Luminance 0.59 cd/m2
Luminance spread 0.13 cd/m2 (2 standard deviations)
Exposure value –2.52 stops   (aim for –2 to –3)
Exposure spread 0.32 stops
Area used for calculation 0.504 x 0.504
Camera settings Exposure time: 0.5   ISO: 400   F-number: 2.8
Focal length: 34.9 mm   (35 mm equivalent)
Exposure compensation: 0
White
Screen photo
[open image]
Luminance 465 cd/m2
Luminance spread 32 cd/m2 (2 standard deviations)
Exposure value –0.85 stops   (aim for –2 to –3)
Exposure spread 0.1 stops
Area used for calculation 0.504 x 0.504
Camera settings Exposure time: 1/501   ISO: 400   F-number: 2.8
Focal length: 34.9 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.