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LR 5.2RC Introducing CA's that weren't there before

Aug 4, 2013 7:03 AM

Tags: #correction #lens #chromatic #abberations #5.2rc

Hi,

 

At this point in time I beleive that LR RC5.2 is introducing CA's as they now appear where they didn't before.

 

I noticed there were a couple of other threads about Lens Corrections and now I have just noticed that there are CA's (Purple Fringing) appearing in high contrast areas SINCE the 5.2RC. The Camera/Lens is a pretty common combination of the Canon EOS Mark III and the EF24-105mm f4L IS USM lens.

 

Haven't had any previous problems with this lens on either the Mark II or the Mark III but now I can go back and see there is CA's appearing.

 

Please note that I tested these images with other RAW processors and there were no CA's.

 

CAs Introduced.jpg

Don.

 
Replies
  • Currently Being Moderated
    Aug 4, 2013 7:07 AM   in reply to BKKDon

    Lightroom cannot "cause" this to happen. My suspicions are that you are just noticing what was there before, or else Lightroom's display has become more accurate. However, that's just my opinion.

     
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  • Currently Being Moderated
    Aug 4, 2013 11:08 AM   in reply to BKKDon

    The CA you’re talking about, the purple fringing next to blown-out areas, is not something LR corrects with its Auto-CA controls but it might become more or less visible by other things that are happening.  It is what the Defringing controls are designed to help with, although those can do things to other parts of an image that also contain the same purple color.

     

    Can you provide a couple screenshots from LR5.2 RC and LR 5.0 or LR 4.x to show what is different in what you see when viewing the same image?

     

    Can you provide a sample DNG of you raw file with its embedded metadata updated to your current settings, for experimenting with in LR 4.x and LR 5.2RC?

     
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  • Currently Being Moderated
    Aug 5, 2013 12:28 AM   in reply to BKKDon

    The factory default defringe amounts are zero for both products, and the defaults for each product are saved independently of each other.

     

    At some point you saved a new set of defaults for ACR that had a non-zero defringe amount, but have not done so with LR, yet.

     
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  • Currently Being Moderated
    Aug 5, 2013 6:11 AM   in reply to BKKDon

    So your Import preset, with Defringing amounts set to zero, is overriding your non-zero defaults?

     

    Defringing is a manual operation independent of Auto-CA or any associated lens profile.

     
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  • Currently Being Moderated
    Aug 5, 2013 3:00 PM   in reply to BKKDon

    The import preset you’re using sets many things including Defringing-amount values to zero, so I’d expect defringing to be shut off if you used that preset.  You could edit the preset file with a text editor to remove the lines if you don’t want that to happen.

     

    Are you using that same preset in LR 5.0 and LR 5.2RC and you get defringing in one and not the other, or are you only getting defringing set to 0 when you use that preset, which would make sense.

     

    ACR wouldn’t care about LR’s import preset so it would use whatever its current defaults are, which must be +2/22-42.

     

    ACR would only care about LR’s defringing values if you actually updated the DNG with the LR settings, which you can do via a menu option.  Are you writing XMP metadata into your DNGs or not?

     

    Are you converting to DNG upon import or are you exporting a DNG out of LR and then viewing or importing into other things?

     
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  • Currently Being Moderated
    Aug 5, 2013 6:20 PM   in reply to ssprengel

    The factory (Adobe-provided) defaults for the 5D Mark III have Defringe disabled and the Remove Chromatic Aberration checkbox also disabled.

     

    If they are being turned on for new images (with no previous settings), then that is likely because you have previously registered camera model-specific defaults in either ACR or Lr (the settings are shared between the two).  You can reset this in either software.  For example, in Lr, go to Develop module on a given image from this camera and hold down option/alt and press the Reset Defaults button in the right panel.

     
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  • Currently Being Moderated
    Aug 5, 2013 7:56 PM   in reply to BKKDon

    There are two different areas of CA/Defringing that are being confused:

     

    AutoLateralCA does NOT control the manual Defringing that you see set as +2/22-42—those are the manual defringing parameters.

     

    AutoLateralCA controls an automatic, hidden, behind-the-scenes lateral CA detection and removal that tries to resize the R, G and B channels about the computed optical center so the channels coincide with each other and fringes of all colors are removed.   This CA is Lateral because it is more the further you get from the optical center.  The other type is Axial CA that is caused things being out of focus front-to-back and impossible to detect remove by resizing the color channels so may need to be removed by manual defringing.  

     

    The preset parameters labeled as Defringe-something are the manual user-controlled defringing that searches for areas of designated colors near an edge and desaturates them.  These are what you are setting to 0 in your preset in LR 5.2RC and so you’ll see these areas of non-lateral CA.

     
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  • Currently Being Moderated
    Aug 5, 2013 10:02 PM   in reply to BKKDon

    Every setting has a default value if you don’t override it with an import preset.  Most of them are zero from the “factory” when the initial version of LR or PS/ACR is installed, but it is possible to save your current settings as new defaults in both LR and ACR, and perhaps you did that at some point in the forgotten past,

     

    I would expect LR 5.2 RC to act the same as LR 5.0 if you don’t apply an import preset.  Does it?

     

    If not, can you provide a DNG via dropbox.com or similar?

     
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  • Currently Being Moderated
    Aug 5, 2013 11:19 PM   in reply to BKKDon

    BKKDon wrote:

     

    Well what is causing these values to be set in LR5.0, CS6 (ACR 8.1) and CS6(ACR 8.2) on import?

    Theoretically, develop settings like:

     

       DefringePurpleAmount=0,

       DefringePurpleHueLo=30,

       DefringePurpleHueHi=70,

       DefringeGreenAmount=0,

       DefringeGreenHueLo=40,

       DefringeGreenHueHi=60,

     

    Dunno where they'd be coming from, other than the obvious places (default settings, import preset...) - sorry I'm not more help.

     

    R

     
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