| Contrast ratio | 770:1 |
|---|---|
| Monitor model | Canon PowerShot A40 |
| Submitted | 21 Mar 2008 08:48 CET, by 75.164.*.* |
| Camera model | Canon PowerShot A40 |
| Processing remarks | Note: image file 1: suggested exposure time: 0.5 s (Set EV to -1.1) |
| Black | |
| Screen photo |
|
| Luminance | 0.62 cd/m2 |
| Luminance spread | 0.11 cd/m2 (2 standard deviations) |
| Exposure value | –1.43 stops (aim for –2 to –3) |
| Exposure spread | 0.25 stops |
| Area used for calculation | 0.504 x 0.504 |
| Camera settings | Exposure time: 1 ISO: 400 F-number: 2.8 Focal length: 34.9 mm (35 mm equivalent) Exposure compensation: 0 |
| White | |
| Screen photo |
|
| Luminance | 479 cd/m2 |
| Luminance spread | 22 cd/m2 (2 standard deviations) |
| Exposure value | –0.5 stops (aim for –2 to –3) |
| Exposure spread | 0.07 stops |
| Area used for calculation | 0.504 x 0.504 |
| Camera settings | Exposure time: 1/403 ISO: 400 F-number: 2.8 Focal length: 34.9 mm (35 mm equivalent) Exposure compensation: 0 |
![[open image]](upload/cr000/00174a.jpg){kind=link}
![[open image]](upload/cr000/00174b.jpg){kind=link}
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.