Color temperature changing during video shot (7D)

[ri_baptista]

Hello!

Yesterday I shot some videos with my 7D and after downloading the videos to my laptop I noticed every movie starts with the correct color temperature and after a few seconds the colors seem a lot hotter.

Does somebody knows why this happens and how can I prevent that?

Here are some facts:

* I was using Live View so I could trigger movie recording remotely from my laptop (I was shooting alone).

* I recorded SEVERAL takes within a period of 4 hours, each take lasting about 2 minutes, and waiting about 1 or 2 minutes before starting recording the next take (sometimes I started immediately). I kept just the very last ones, so I don't know if this issue was happening during the first takes. Could this problem be related to camera sensor working for hours straight, even taking a break of 1 or 2 minutes between each take?

* Light sources remained constant during the entire recording session.

Below are some screenshots so you can see what I'm talking about:

Thanks!

AT THE START OF THE VIDEO:

AFTER A FEW SECONDS (notice how skin tones changed drastically):

 

[FotosbyMike]

Was your WB set to Auto anything or manual? If it was Auto anything the glare off the guitar appeared too cool(Blue) so it warmed(adding yellow) to the video.

 

[KmH]

What type of light is your light source? Fluorescent? Tungsten? LED?

 

[ri_baptista]

Hi @FotosbyMike

That makes total sense... I've just checked WB is set to Auto on EOS Utility Software. Tonight I'm gonna try to set it to a fixed value (fluorescent).
I didn't know an Auto WB setting would make it dynamic DURING video shooting. I thought it would remain constant after video recording started.

Thanks!

 

[ri_baptista]

Hi @KmH!

It is a fluorescent lamp.

 

[KmH]

As fluorescent lights cycle through the AC voltage range (+60 V to -60 V) their color temperature changes making fluorescent lighting a poor choice for shooting video.
Particularly if you have the White Balance set to AUTO.

The other issue with fluorescent is flicker, again because of the voltage cycle rate - 60 cycles per second in the US.
To shoot video with a DSLR we want to set the shutter speed to 2x our frame rate, which puts us on shutter speeds too close to 60 cycles per second.