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SL2-s Strange color shift


opera207
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Hello!

Does anyone know this behaviour? When I set the colour temperature to warm light (bulb symbol) in the SL2-S and use a warm light source, colour shifts occur in the camera. Certain yellow tones become magenta-red, which ruins the skin tones. However, this only happens when I shoot directly in JPG. In RAW and the RAW converters, the colours are fine. Although I rarely shoot in JPG, the image appears with the wrong colours in the EVF, which irritates me every time. Unfortunately, this has not changed with the firmwares, but it seems to be only a software problem. I must add that the light source is warm LED light. Maybe this doesn't happen with "real" tungsten light, but I couldn't check that.

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2 hours ago, jaapv said:

LED light is totally impossible, as it has a discontinuous spectrum...

Exactly - and so are other light sources, such as sodium vapor or mercury vapor.

It is also a general principle that white-balancing out yellow (even from old-fashoned hot-tungsten bulbs), removes too much yellow from "shades-of-orange" skin tones, leaving them too pink/red.

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It usually requires a whole separate camera profile ("red hue" shifted towards yellow in the post-processing calibration panel) to shoot under yellow light and get good results.

Every one of the "gaps" in these light-source spectrums, compared to the full-daylight spectrum, are colors that a digital camera (and even some film) can and often will get fouled up. Discontinuous data.

http://www.lamptech.co.uk/Documents/SO Spectral.htm

Now, the in-camera automated processing of jpegs in a couple of seconds can also be screwed up, compared to hand-adjustment on a computer for 30 minutes.

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Added to which, real tungsten which is a continuous light source contains a large amount of IR light which can overwhelm a thin IR filter (*). As some of the skin layers and blood are highly IR reflective this will result in purple blotches on pale skin. 

(*) The SL has a relatively thin filter as it has to be able to accomodate M lenses.

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  • 3 months later...

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Yes I have noticed that myself, I always shoot JPEG. I call it "peach", an orangy pink that looks pretty awful. Its not only on skin tones but it makes a lot of wamer colours look unnatural.  Tungsten is most obvious and tricky to fix but I also see it in daylight. My only work around is always using Manual WB, which I shift towards the blue spectrum until that awful peach hue goes away. As a result a lot of my photos end up being on the cool end of the spectrum. I've owned two SL2-S's and they both did it.

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A better remedy is to use a IR cut filter in such circumstances.
In general, it is better to use the specific colour controls in LR and C1 than to apply a correction that affects all colours. Try pulling down the Magenta.
Shooting raw gives you far more leeway for such corrections. Avoid using jpg unless there is a good reason to use it; you are throwing away half the data that the sensor provides. In any case use jpg and raw to give yourself the chance of fully processing an image that needs it.

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Posted (edited)

I have a Lightroom preset I call 'pink skin reduction', which shifts the red hue towards orange, reduces the red & orange saturation while increasing (lightening) red & orange luminance. It's my quick and dirty fix for pink-blotched skin but it won't stand up to close examination. I found playing with magenta was less effective.

My 'break glass in case of emergency' solution is conversion to monochrome.

Edited by LocalHero1953
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  • 4 months later...
On 5/5/2022 at 2:04 PM, jaapv said:

A better remedy is to use a IR cut filter in such circumstances.
In general, it is better to use the specific colour controls in LR and C1 than to apply a correction that affects all colours. Try pulling down the Magenta.
Shooting raw gives you far more leeway for such corrections. Avoid using jpg unless there is a good reason to use it; you are throwing away half the data that the sensor provides. In any case use jpg and raw to give yourself the chance of fully processing an image that needs it.

Sadly, I've sold my sl2-s, yes the problem can be fixed in picture raw files, but it appears during video shooting too, which is very hard to deal with in the post.

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On 2/3/2022 at 8:30 AM, jaapv said:

Added to which, real tungsten which is a continuous light source contains a large amount of IR light which can overwhelm a thin IR filter (*). As some of the skin layers and blood are highly IR reflective this will result in purple blotches on pale skin. 

(*) The SL has a relatively thin filter as it has to be able to accomodate M lenses.

Yes this may be the cause of the problem.

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