White Balance Help part II

[peeker]

Here is a better example of the weirdness I saw... notice all of the shots are the same shutter speed, white fluorescent light selected for white balance and six consecutive shots on high speed.

Notice how on the last shot, the color is more corrected, but how it moved around prior to that....

Any help?

[jonney]

I've shot in the same situation with the same result with a 40d. I don't know why the camera does what it does, but I would recommend setting a manual white balance in the room with a gray card or a white balance lens cap. That way your camera doesn't have to do any evaluating while you are shooting.

I have one of these and it's fine: http://www.amazon.com/Mennon-White-b...4811555&sr=8-1

jf

[CaptainTom]

The only explanation I can think of is that these look like sodium vapor type lights, and not true fluorescent lights. Sodium Vapor lights actually strobe at an extremely high rate, which causes them to sometimes get caught between full luminous and less than full luminous cycle if you use a high shutter speed.
I would run into this a lot when shooting on raquetball courts, etc.
Notice that the color balance in the background is fairly even throughout each exposure. The imbalance is isolated to your subject, and you can almost see the strobing effect on her uniform.
Using a slower shutter speed will overcome this phenomenon, but that defeats the need to stop the action.
Solution? Shoot RAW and dial in an arbitrary Kelvin number as your white balance. When processing the RAW files, find something in the image that is representative white and adjust the balance image by image.

or

overcome the lights by using strobes.

[peeker]

There is a part of it that makes sense. Didn't see any sodium lights, although anything could be possible. One thing that I'm thinking is I had my camera set on Av. Later, once I set it to M @ f/ 2.5 and 1/250 - 1/500... the shift went away.

Still baffles me... Now I just have a mess to clean up to make the images sorta match... its a darn good thing I only shoot RAW.

[Dobick]

it is my understanding that all lights have a cycle. Stadium lights are worse than fluorescent (meaning cycle at a slower rate) but fluorescent will cycle as well. If you were to dial in a kelvin temp, and shoot with one particular shutter speed and aperture, you would still notice the shift (especially in highspeed action sequences like you are shooting -- and even more so because the subject is wearing what amounts to a big white card. :) ) The good news in this situation is that
a - it is not your camera
b - they are wearing a big white card, so it should be easy to correct in post!

[bret]

scott,
+1 what Capt. Tom says re: strobes.
and for what is worth... tell the lady to "cock" her striking leg more...results in more speed and snap. learned that from ray mccalum and covert blackledge back in the 80s

[jredman]

Kent, you are correct anytime you shoot ambient light you will not get consistent images, lights do cycle and your camera sees that when your eyes do not. To get over that, you have to strobe and get a stop or two over the ambient light.