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Contrast ratio results for iMac 27" (Late 2012)

Contrast ratio 4572:1 (edge: 4572:1)
Monitor model iMac 27" (Late 2012)
Submitted 26 Mar 2024 08:01 CET, by 73.140.*.*
Camera model Canon EOS REBEL T3i
Processing remarks

Warning: image file 1: Underexposed. Please increase the shutter time.
Note: image file 1: suggested exposure time: 7.4 s (Set EV to +4.9)
Warning: image file 3: Underexposed. Please increase the shutter time.
Note: image file 3: suggested exposure time: 7.4 s (Set EV to +4.9)

Black
Screen photo
[open image]
Luminance 0.08 cd/m2
Luminance spread 0.12 cd/m2 (2 standard deviations)
Exposure value –7.39 stops   (aim for –2 to –3)
Exposure spread 2.69 stops
Area used for calculation 0.524 x 0.589
Camera settings Exposure time: 1/4   ISO: 400   F-number: 4
Focal length: 37.7 mm   (35 mm equivalent)
Exposure compensation: 0
White
Screen photo
[open image]
Luminance 374 cd/m2
Luminance spread 32 cd/m2 (2 standard deviations)
Exposure value –0.85 stops   (aim for –2 to –3)
Exposure spread 0.12 stops
Area used for calculation 0.524 x 0.589
Camera settings Exposure time: 1/197   ISO: 400   F-number: 4
Focal length: 37.7 mm   (35 mm equivalent)
Exposure compensation: 0
Black at screen edge
Screen photo
[open image]
Luminance 0.08 cd/m2
Luminance spread 0.12 cd/m2 (2 standard deviations)
Exposure value –7.39 stops   (aim for –2 to –3)
Exposure spread 2.69 stops
Area used for calculation 0.524 x 0.589
Camera settings Exposure time: 1/4   ISO: 400   F-number: 4
Focal length: 37.7 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.