The blue cast in
@Feitelijk's video is indeed a problem that has been seen before in certain other cameras. For example, similar problems existed in early iterations of the Mobius 1 firmware which also sometimes manifested as a Red - Green shift. If you drove by a large red brick building or a bright red vehicle would cross your path the footage would go greenish/cyan for awhile until it recovered.
The problem is related to the RGB (RED-GREEN-BLUE) additive color model used in digital cameras, computers, etc. (as opposed to the CMYK (CYAN-MAGENTA-YELLOW-BLACK) subtractive color model used in pigment based printing and chemical based analogue photographic color printing)
On the RGB color wheel Yellow and Blue are
exactly opposite one another. (as are RED & GREEN) Notice how in
@Feitelijk's examples the image goes from a mostly YELLOW environment to excessively BLUE. This is because the camera is attempting to achieve proper color balance by
adding BLUE in order to compensate for the abundance of YELLOW in the scene but it is overcompensating and the camera has difficulty returning to normal once it sees a normal color environment again.
So, as I've said,
YELLOW and BLUE are
opposite each other on the
RGB color wheel chart.
Notice that the center of the chart is
WHITE.
When
RED-GREEN & BLUE are in proper balance in the
RGB model you get pure
WHITE.
This is what the familiar term "White Balance" is referring to.
Feitelijk's camera is overshooting the white balance point and then slowly returning to normal.
Understanding this concept is the key to resolving this problem in the firmware.
Mobius addressed this problem relatively quickly once they became aware of it.
Feitelijk has been reporting this problem for quite some time now but it has yet to be addressed. This is reminiscent of my dissatisfaction regarding the blooming and blown out upper tonal range issue that went on for a year and half or more from the time I first reported it until it finally received some level of firmware remedy.
For a long time now I've been wondering why a highly rated camera such as the SG9665GC is still on "beta" firmware more than two years after its introduction. Updates, sure that's pretty normal, but I can't think of another digital product I've ever owned that is still on "beta" firmware more than two years after coming to the market. I suppose whatever you call these updates, "beta" or otherwise doesn't really matter as long as major issues get the attention they require but for some reason issues like this seem to linger for a very long time on the GC until they finally get that attention. I do understand that it can take awhile to sort things out but a problem like this does seem to still be a "beta" kind of thing two years in. Like I've mentioned, Mobius got right on it. Then again, maybe this color balance problem hasn't gotten any firmware attention because it hasn't been reported all that often?
Interestingly, now that I think about it the dynamic range/high contrast issue that went on for so long was also a matter of the camera taking far too long to recover to a normal state after an exposure compensation event. Seeing the camera overcompensating for color balance and then taking too long to recover feels in some ways like a similar phenomenon. Perhaps there is something challenging along these lines inherent in this DSP/sensor hardware combination?
For whatever it is worth, I have not personally noticed any color balance or color shift issues whatsoever with my SG9665GC. Since re-calibrating the camera and re-flashing beta 27 results have been quite good except for some occasions when the footage is too dark for the general lighting scenario. Happily this has been less severe than previously and therefore less of a concern. Come to think of it, FWIW, the "too dark" footage thing also seems to be an overcompensation exposure issue.
The only recent problem I've had was discovered just this morning upon reviewing some footage from yesterday. Apparently the last file on the memory card is corrupted and unplayable. Hopefully, this is some sort of one-off and not a harbinger of some other brewing problem. Yesterday morning it was - 4 degrees below zero Fahrenheit when I woke up in the morning and the camera was out in my truck all night but I have no idea if that could have anything to do with the bad file. If it happens again I'll try a fresh memory card and go from there.