BLUE flares

Though I know a few individuals on this board that will argue with me, but I have found that in situations where the color temperature is very high (such as you have here - likely 8000 K or above) the blue CCD channel can exhibit a non-linear response in highly exposed situations. The fix that I have found to work is to use a warming filter (85b) and then color balance the camera with a white (but not over exposed) reference.

My initial assumption was that there could be a peak in the UV region, but investigation using an industrial UV source didn't show any correlation. The cause for these "flares", at least the one that currently appears to be most plausible, is that there is a non-linear response in the blue CCD. I do intend to fully investigate this at some point in time, but the fix that seems to always work is to use a warming filter.
 
I am curious, does this just happen at one part of the lens range, like telephoto (45mm) or everywhere in the zoom range.

Thank you

Bill Turner
Schneider Optics
Century Division
 
hmmm. K check this out then... I was filming with my matte box with my
16:9 lens. I had a 4x4 ND grad # 6 filter on. As u can see a bit of the
corner of the matte box is showing. You can see the BLUE flare thing ma
jig on the left side. There was no high expose area for this shot... It happens everywhere in the zoom range.

http://www.ozanbiron.com/sky.jpg
 
Ozan, I'm having the exact same problem with my 100e. My theory is that it has to do with head wear, as I'm looking at some old footage from my camera (when it was owned by a professional music video producer), the blue jig thing is there, but much less significant.

I'm getting my camera back from cleaning in exactly 24hrs, hoping to see some improvements.
 
I don't think that "headwear" has anything to do with it as I have seen the same thing capturing directly to a computer.

I haven't seen any correlation between the phenomena and zoom setting.

The image posted by Ozan_Biron is interesting as it isn't highly exposed, but still fits the high color temperature condition. Could this have been a very localized flare off the mattebox just at the edge? If this was the case, then it would fit both criteria nicely (high color temperature and hot exposure).

Has anyone else used the 85b (or any warming filter) fix?
 
One more question,

does it happen with and without the anamorphic? Since the Panasonic Anamorphic is just two elements, it is not well corrected for color and blue is the hardest to correct.

We have hand issues with blue flare in the telephoto range of a number of camcorders by different manufacturers and did experiment with "warming type" filters as they cut off the blue to varying degrees (depending on the design and strength of the filter) tending to minimize of eliminate the problem depending on the degree of the problem and how much of the blue one is willing to "throw away".

Bill Turner
Schneider Optics
Century Division
 
Most likely what you are experiencing is related to CineGamma and clipping. CineGamma has no protection against overexposure "blowouts", and can lead to the situations you're describing.

Try shooting the same shot in Normal gamma, and then in CineGamma, and see if the blue goes away in the normal gamma shot. It should.

The moral of the story is, you can't let CineGamma overexpose and clip the highlights, or you run the risk of this happening.

The stuff on the left edge of the frame is totally unrelated -- that happens all the time. Some cameras put up a black bar to cover up that vertical column of pixels, the DVX doesn't. But all cameras do that at the edge of the frame.
 
I've had a similar thing while shooting during the day, but I had a Canon polarizer filter on it. So it had a purple haze on it. The thing is, I later switched to a higher ND-filter on the camera and the purple haze was gone. Similar conditions, similar shot and angle. So my guess is that is has something to do with the amount of light entering the camera. Although I am not sure whether it is exactly the same problem. My camera is brand new so it has nothing to do with wear on the camera.
 
You must log in or register to reply here.
Back
Top