Contrast ratio results

Black
Contrast ratio	22721:1
Monitor model
Submitted	21 Feb 2016 13:41 CET, by 5.35..
Camera model	Pentax K-r
Processing remarks	Warning: image file 1: Underexposed. Please increase the shutter time. Note: image file 1: suggested exposure time: 437.6 s (Set EV to +16.1) Warning: image file 2: automatic white balance can cause inaccuracies. Warning: Image F-number settings are not the same. Warning: Image focal lengths/zoom levels are not the same.
Screen photo	[open image]
Luminance	0.01 cd/m2
Luminance spread	0.01 cd/m2 (2 standard deviations)
Exposure value	–18.6 stops (aim for –2 to –3)
Exposure spread	4.25 stops
Area used for calculation	0.681 x 0.766
Camera settings	Exposure time: 1/160 ISO: 200 F-number: 6.3 Focal length: 49 mm (35 mm equivalent) Exposure compensation: 0
White
Screen photo	[open image]
Luminance	156 cd/m2
Luminance spread	47 cd/m2 (2 standard deviations)
Exposure value	–3.05 stops (aim for –2 to –3)
Exposure spread	0.44 stops
Area used for calculation	0.722 x 0.812
Camera settings	Exposure time: 1/60 ISO: 200 F-number: 7.1 Focal length: 52 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.