Am Dell U2715H  Brightness 50/ Contrast 50 
abstand zu kamera 1m

EOS 600D
ISO 800 F5.6.  Kit @55mm
gray eos    ldr /brightmode ldr
0% 1.3s     580/70
10% 0.3s    720/85
20% 1/10    1075/140
30% 1/25    1555/230
40% 1/50    2020/350 
50% 1/80    2410/495
60% 1/125   2735/653
70% 1/200   2950/800
80% 1/250   3140/965
90% 1/400   3295/1130
100% 1/500  3400/1280