I've a white balance problem - any ideas?
Posted 05/04/2008 - 23:33
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I would urge everyone to read the Wikipedia article, which explains the whole thing rather well, plus gives the appropriate references.
Best regards, John
Posted 06/04/2008 - 12:11
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Quote:
snip . . They should ALL flicker at the same time, since the current changes at the same time for ALL of them.
That is assuming that they are all on the same phase. I would think that in a large hall that the lights may well be on different phases, although a bank of lights would have to all be on the same phase as there are regulations in the UK concerning the distance between two phases.snip . . They should ALL flicker at the same time, since the current changes at the same time for ALL of them.
I'm not sure what it proves but I've just shot the following sequence using my nice new K10D (thanks SRS)
1/2000s at f3.5 / ISO 400 / Manual white balance set to fluorescent light - daylight colours / burst mode - jpeg
To my untrained eye the colour temperatures do appear to change.
Steve
Posted 06/04/2008 - 13:13
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Quote:
I've just been looking at http://en.wikipedia.org/wiki/Fluorescent_tube
Modern tubes with electronic ballast are flicker-free, but notwithstanding that, the article reminds us of the way these tubes work.
The charged gas is in plasma state and releases photons in the UV part of the spectrum. These photons hit and excite the phosphors than line the glass tube. The phosphors fluoresce with visible light, just like a CRT monitor. The colour of the light depends upon the phosphors used, not the nature of the AC power.
There is no mention in the article of changing colour balance and I really don't see how there would be.
Hope that helps!
Wikipedia stated that COMPACT fluorescent WITH electronic ballast are "flicker" free. The standard 4ft and 8ft are NOT flicker free.
I've just been looking at http://en.wikipedia.org/wiki/Fluorescent_tube
Modern tubes with electronic ballast are flicker-free, but notwithstanding that, the article reminds us of the way these tubes work.
The charged gas is in plasma state and releases photons in the UV part of the spectrum. These photons hit and excite the phosphors than line the glass tube. The phosphors fluoresce with visible light, just like a CRT monitor. The colour of the light depends upon the phosphors used, not the nature of the AC power.
There is no mention in the article of changing colour balance and I really don't see how there would be.
Hope that helps!
Posted 07/04/2008 - 10:41
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For processing images with tricky WB in Silkypix, see:
https://www.pentaxuser.com/forum/viewtopic.php?t=7242
This is a tip for using the skin tool, so it's only useful if you're photographing people.
Jonathan
https://www.pentaxuser.com/forum/viewtopic.php?t=7242
This is a tip for using the skin tool, so it's only useful if you're photographing people.
Jonathan
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1603 posts
18 years
North of Montreal,Quebec,
Canada
I was going to quote one post but there are nuggets of truth in many of them.
here's my take:
Fl lights cycle off and on but it is now very unusual for them all to be doing it together, if the pictures were taken in an old building with old lights then maybe this would be the cause. Flourescent lighting is murder, the spectrum is incomplete, to white balance, as Don says manual WB is the way to go but you are never going to get the range of colours you get in daylight.