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jarau_de
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LR 4.2 D600 deep shadow magenta color cast

Oct 29, 2012 4:18 AM

LR4.2 gives some ugly magenta color cast on deep shadows especially at high iso pictures. Nikon Capture NX2 gives them too, but not  so heavy. If I push the shadows at iso 1600, they are all magenta. Is it related to the beta state of the D600 support? My D700 is at iso 3200 in deep shadows completely black (only luminance noise), even pushed. Is there a possibility to correct that issue with LR (high iso blackpoint correction)? The shadow color tint correction from the calibration option is not really a solution, because it does not only correct the deep shadows, so the other shadows  get a green tint.

 
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  • Currently Being Moderated
    Oct 29, 2012 4:29 AM   in reply to jarau_de

    The following is copied from the release notes for LR 4.2 on the Lightroom Journal website.

     

    "Please note that the support for Nikon D600 is preliminary and there is a minor risk that the appearance of your images may change when the final support for Nikon D600 is available in an upcoming release."

     
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    Oct 29, 2012 7:44 AM   in reply to jarau_de

    I don't see this with files from my D600. Can you show an example? Also, if you want I can send two profiles I created using a colorchecker that give subtly different color rendering from the built-in beta profile.

     
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    Oct 29, 2012 8:20 AM   in reply to jarau_de

    I don't see it neither with my D600 files.

    I shot some images at dusk at ISO 2500, there's quite a bit of noise overall but no magenta in the shadows. WB was set to Auto.

    Even at ISO 12800 there's no magenta in the shadows.

    What WB setting did you use on your D600?

     
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    Oct 30, 2012 2:10 PM   in reply to jarau_de

    i also face this problem...

    _DSC0353.jpg

    _DSC0610.jpg

     
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    Nov 2, 2012 7:01 AM   in reply to jarau_de

    The purple is indeed amp glow - infrared photons generated by the electronics exciting pixels on the sensor. This can be fixed by a black level adjustment indeed. Lightroom still has this and it can be done most efficiently with the curves adjust. Just move the left bottom point slightly to the right. You can also do this in the DNG profile editor and generate a profile that does it. This is one thing that LR3 had better control over with a specific black slider. I personally see a lot less glow than the above images so perhaps there is per body variation on this. I also wouldn't be surprised if the final, non-beta profiles are better at this.

     
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    Nov 5, 2012 6:47 AM   in reply to jarau_de

    Commenting on the two example images:

     

    Amp glow, caused by warm internal components adding electrons to various areas through heat, is a given in astrophotography and is removed, along with other pattern noise using dark-frame subtraction, which doubles the exposure time, and is usually available as some type of high-ISO noise-reduction in the camera settings.  Is there a reason this form of in-camera noise-reduction was not used in the night-time exposure, shown? 

     

    Adobe’s raw processing doesn’t have the capability to subtract a synthetic dark-frame the may have been created by Adobe through profiling of a camera, but why should they, when the camera, itself, can do this, and be more accurate as well.

     

    DXO does do things differently than Lightroom, so if you need what it does, isn’t it possible to create linear-DNGs and process those, further, in LR?

     
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    Nov 5, 2012 9:54 AM   in reply to DdeGannes

    DdeGannes wrote:

     

    The following is copied from the release notes for LR 4.2 on the Lightroom Journal website.

     

    "Please note that the support for Nikon D600 is preliminary and there is a minor risk that the appearance of your images may change when the final support for Nikon D600 is available in an upcoming release."

     

    Please note what is said above, as it is likely at least a portion of the issue.

     
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    Nov 13, 2012 12:30 PM   in reply to jarau_de

    I believe Adobe only profiles noise overall for an ISO range, not by regions of the sensor, which DxO may do.  Maybe in a few releases they’ll do something like this, but not for now.

     
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    Nov 13, 2012 1:20 PM   in reply to Astrowheat

    Astrowheat wrote:

     

    i also face this problem...

    _DSC0353.jpg

    _DSC0610.jpg

     

    It appears the magenta shdow area in the above shot is confined to the bottom edge of the image.  I just discussed this on a similar post concering a Canon 5D MKII with the same issue in the bottom corners of the image. I suspect it may be due to light entering the viewfinder and leaking into the mirror box:

     

    http://forums.adobe.com/message/4843206#4843206

     

    It's simple enough to try similar shots with the viewfinder blocked. When I shoot images on a tripod I always make it a point to block the viewfinder with the Canon strap mounted blind, a hat, or even my hand to keep direct light from entering the viewfinder. The only thing between your viewfinder and the image sensor is the foam seal that the mirror rests on in the up shooting position. At high ISO even the tiniest light leak could cause fogging of the image, and it will be most visible in the image bottom edge or corners (i.e. image is upside down on the sensor).

     
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    Nov 13, 2012 1:28 PM   in reply to trshaner

    trshaner,

    your post triggered a thougt: Nikon recommends that the viewfinder of the D600 be covered with the supplied viewfinder cap when shoting in Live View.

    I don't know if the OPs picture was taken in Live View.

     
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    Nov 13, 2012 1:55 PM   in reply to web-weaver

    Live view and high ISO is also a bad combination, since it causes sensor heating and significantly raises both Chroma and Luminance noise levels.

     
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