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Chromatic aberration

C300 Zeiss High Speed

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#1 bogdanovici barbu

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Posted 26 January 2013 - 01:05 PM

Hi guys!

A while ago I shot an advert with my friend's C300 and on a couple of shots the image had a green-ish hue. It wasn't that bad and we were able to fix it rather easily in CC.
A week or so ago, my friend shot a video (using his C300) and he had the same problem only it was 10 times worse. He was shooting in a „golden” room and all that gold turned out to be a pretty sick green, which wasn't that easy to correct.
Both situations were tungsten lit(no color filters, only diffusion), and shot through the same set of old Zeiss High Speed T1.3 lenses.

So.. is it be the camera, or is it the glass - in which case, can chromatic aberration go as far as turning gold into green? Could it be something else??

Any input on the matter will be much appreciated!
Thank you!
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#2 Simon Wyss

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Posted 26 January 2013 - 01:23 PM

It’s the video issue.

The very narrow Green reception band, if bandwidth at all, of the sensors are not favorably counterbalanced by Red and Blue. I presume that you know about Red and Blue fifty-fifty forming Magenta as opposite colour to Green. You can screw out with Red and Blue as much as you want, that stubborn Green channel will not give in. It’s either in or not.

Our much wider ocular colour reception is rather forgiving for Green content, especially on shiny surfaces. So golden reflections can look pretty fine to you while the video camera has its Green tap just bursting. Film is closer to ocular reception based on the sensitivity of chemical compounds, not metal oxide field effect transistors.
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#3 bogdanovici barbu

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Posted 29 January 2013 - 05:54 PM

Thanks a lot Simon. You might be right on this one - meanwhile i've learned that this particular camera having a 4k sensor and 1920:1080 output, the math is basically 4 pixels on the sensor output 1 pixel of image. These 4 pixels are as follows on RED one BLUE and TWO GREEN. So I think this is the main sensor ”feature” which causes the green tint.

Thanks again!
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#4 Mike Lary

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Posted 29 January 2013 - 09:13 PM

meanwhile i've learned that this particular camera having a 4k sensor and 1920:1080 output, the math is basically 4 pixels on the sensor output 1 pixel of image. These 4 pixels are as follows on RED one BLUE and TWO GREEN. So I think this is the main sensor ”feature” which causes the green tint.



What you're describing is a bayer pattern, which is widely. The reason for the additional green pixel is related to luminance, not chromaticity. Your issue is most likely caused by internal processing in the camera. You aren't recording raw data, so your white point is baked in. I would look at the custom white balance settings / matrix settings in-camera and tweak the white balance / dial out the bias.

Edited by Mike Lary, 29 January 2013 - 09:15 PM.

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