fluorescent light, white balance, shutter speed and color cast

So you are shooting an event in fluorescent light conditions and think you got the camera’s white balance right. Right? Still, you end up wit lots of shots that have an ugly, mostly yellowish color cast? I have recently shot a kickboxing training session, and that’s exactly what happened.

Here’s an example of two subsequent  shots (unprocessed originals):

The background in the first picture is yellowish, while in the second it is more neutral. The kickboxers in the foreground, however, have the same color both. Here’s another example:

 

Here both the background (the door and reflection in the mirror, which is behind me) have a cast in the first pic, the second again is more neutral.

So what is it? The camera WB was set to fluorescent, but within a fraction of a second it gives me two different results. While chimping (looking the result on the LCD) I noticed it and was confused at first. I did not bother about it too much, as fixing WB is not such a problem. But then I noticed that in some pics the color cast applies only to a part of the pic, and that’s more tricky. After some more confusion I remembered. Those darn neon lights…

Neon (fluorescent) lights  flicker at about twice the frequency of the current feeding them, meaning that an entire flicker cycle will be between 1/100 and 1/120 second. During such a cycle the light’s intensity and color temperature changes.  Using a shutter speed  faster than that, as I did, then that’s exactly what happens. I was using shutter speeds between 1/400 and 1/800, and in almost every sequence of frames shot in a row (at 9 fps), I have at least one with a color cast.

A possibility to overcome that problem is to shoot with flash at shutter speed slower than 1/100. Here an example shot at 1/20 with bounced flash bounced:

Gilbert Ludwig Sports Photography

 

The other option is that you don’t bother, hoping the good shots have no cast, and if they have, fix them.  Black & white conversion does the job too:

 

 

Gilbert Ludwig Sports Photography

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