this problem seldom happen when shoting at high ISO level from 6400 and above. the yellowish gradient appear on the picture. anyone can clarify what problem is this? or faces similar problem like this? shoting in bedroom under just one fluorescent light. i always shot with auto WB.
TQVM for ur response.
#1. "RE: Best guess" | In response to Reply # 0
> shooting in bedroom under just one fluorescent light.
Fluorescents send out regular pulses of different coloured light.
The individual light pulses are too fast for the eye to detect.
With the slight delay between white balance reading and shutter open AWB may have the wrong setting at the moment of exposure.
Also if your exposure is long enough to pick up individual coloured pulses as the shutter travels from top to bottom of the camera in a total time equivalent to around 1/400 of a second different parts (horizontal "slits") of the picture can be exposed to different coloured light.
Photography is a bit like archery. A technically better camera, lens or arrow may not hit the target as often as it could if the photographer or archer does not practice enough.
#2. "RE: Best guess" | In response to Reply # 1
You're right, Len.
This behaviour is also the main reason why professional fluorescent lighting is very often made with a three-phase power system providing a good overlapping of the fluroescent pulsing. Such a system also substantionaly reduces light flickering.
The solution to the issue is to:
1. use the three-phase fluorescent lighting (not very likely to be found in home installations)
2. use long exposure time -- equal to or longer as the 1/50th of the second (1/60th in USA) in order to expose during the whole cycle.
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