Shifting white balance

F

firestarter

New member
We have an XL2 (this has actually also happened with our XL1 as well) and sometimes when we shoot the white balance will shift on its own from cool to warm over and over. This happened recently when we were shooting inside using halogen lights and the white balance was set to the indoor setting. You could distinctly see a wall turning blue then orange. It doesn't always seem to happen, though.

Any ideas what is causing this?
 
It only seems to happen with certain types of artificial light, but it happens with manual white balance too if the camera is allowed to vary the shutter speed. I'm not sure what the reason is, but if you fix the shutter speed (Tv mode) then the colour doesn't shift.

Richard Hunter
 
it happens with manual white balance too if the camera is allowed to vary the shutter speed. I'm not sure what the reason is said:
The XL2 was in Manual mode, with the gain set to 0 and there were no windows in the room. So the shutter speed shouldn't have changed much throughout the shoot. For example, during the course of a 30 sec. take the white balance would shift from warm to cool twice before it was over.
Click to expand...
 
My experience was that setting the shutter to 1/50s cured the colour shift. Maybe I shouldn't have generalised by saying that any fixed shutter speed would be OK. It sounds like it might be related to the supply frequency. What shutter speeds were you using at the time?

Richard
 
Happens to me all the time with both the XL2 and the DVX100 when in 24P modes and under fluorescant lighting using the 1/48 shutter speed. Changing to 1/60 shutter eliminated this problem entirely. Other speeds (1/75-1/100) just changed the rate at which the color shifts occurred. It has something to do with the phase of the 60hz line interacting with the non 1/60 shutter. I'd guess it is a similar issue with you but with the shutter and hz being different for whatever region you are in.
 
try shooting in cs mode for shutter speed on the xl2 and see if that elminates the problem based on icicle22's theory. I have had this problem in teh past as well (very annoying when trying to chroma key) but i have heard it is probably the light source that is unstable with the color temperatures it outputs. I like icicle's explanation better however.
 
I believe Icicle is right here, since flourescents operate at 60Hz you will need to shoot with a shutter speed of 1/60 to be in sync with them. Shutter speeds of 1/120, 1/240 and so on will work as well as they are multiples of 1/60. However I don't recall if the XL2 is capable of shooting at these speeds.

1/30 will work too, as it is divisible into 1/60.

With any of these fixed shutter speeds you should have no problems, unless the power supply is not operating at 60Hz (shouldn't be a problem in the U.S.).
 
You must log in or register to reply here.
Back
Top