Contrast ratio results for Dell U2717D

Black
Contrast ratio	4541:1
Monitor model	Dell U2717D
Submitted	27 Jan 2018 06:50 CET, by 124.106..
Camera model	Apple iPhone 7
Processing remarks	Warning: image file 1: Underexposed. Please increase the shutter time. Note: image file 1: suggested exposure time: 1.0 s (Set EV to +2.1) Warning: image file 2: exposure time below 1/500 sec is unreliable. Try increasing the EV compensation. image file 2: Note: image seems to be noisy. Try reducing the ISO setting or increasing the exposure time.
Screen photo	[open image]
Luminance	0.29 cd/m2
Luminance spread	0.13 cd/m2 (2 standard deviations)
Exposure value	–4.57 stops (aim for –2 to –3)
Exposure spread	0.68 stops
Area used for calculation	0.404 x 0.404
Camera settings	Exposure time: 1/4 ISO: 160 F-number: 1.8 Focal length: 28 mm (35 mm equivalent) Exposure compensation: 0
White
Screen photo	[open image]
Luminance	1327 cd/m2
Luminance spread	193 cd/m2 (2 standard deviations)
Exposure value	–1.41 stops (aim for –2 to –3)
Exposure spread	0.21 stops
Area used for calculation	0.404 x 0.404
Camera settings	Exposure time: 1/2037 ISO: 160 F-number: 1.8 Focal length: 28 mm (35 mm equivalent) Exposure compensation: 0

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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.