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Where are the CA sliders in ACR 6.7 beta?

Apr 10, 2012 9:32 AM

In ACR 6.6, Lens Correction -> Manual -> Chromatic Aberration has sliders to Fix Red/Cyan Fringe, Fix Blue/Yellow Fringe. Those sliders are missing in 6.7 beta.

 

I hope Adobe puts them back.

 
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  • Currently Being Moderated
    Apr 10, 2012 12:20 PM   in reply to Lance Warley

    ACR 6.7 is utilizing the new chromatic aberration control that has been introduced in Lightroom 4, and will be part of the new ACR 7.  It is a single check box at the bottom of the lens correction tab.

     
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  • Currently Being Moderated
    Apr 10, 2012 1:00 PM   in reply to Lance Warley

    Most people that have commented on the new feature seem to agree with Adobe that the new control is much better.  If it isn't for you, then stick with ACR 6.6.  Or alternatively voice your concerns.

     
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  • Currently Being Moderated
    Apr 10, 2012 9:28 PM   in reply to Lance Warley

    I'd actually like it if they put them back (or improve  the function).  I've just finished working in Iraq with lots of backlit subjects and the new tickbox doesn't work well enough (yet?) so I've got to work out how to remove 6.7 and then install 6.6 so I can deliver urgent images to clients.

     
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  • Currently Being Moderated
    Apr 10, 2012 9:51 PM   in reply to MJCRPJ

    MJCRPJ wrote:

     

    I'd actually like it if they put them back (or improve  the function).

     

    Don't be surprised if Adobe adds some new functionality in the near future...

     

    The bottom line is the the current Auto CA works very, VERY well for classic Lateral CA. What a lot of people were using the manual siders for isn't Lateral CA but Longitudinal CA. The difference is critical. Lateral CA is the inability of the lens to render all colors the same size–when you get color lateral CA fringing it's because the lens can't correctly size all three colors of Red, Green and Blue the same actual size. The fringing is caused by the size difference between the colors–that's a bit easier to fix than the other form of CA. Longitudinal CA is the inability of the lens to have all three colors of light in the same critical focus...that is a HUGE difference in purpose and execution.

     

    I suspect that the first solution, Auto CA will be followed up by a solution for longitudinal CA at some point. You gotta know that the ACR/LR team is really hellbent on providing the maximum image quality but, they attack the various image defects in an incremental methods...not everything can be fixed in one fell swoop.

     
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  • Currently Being Moderated
    Apr 10, 2012 10:13 PM   in reply to Jeff Schewe

    Jeff, thanks for the very insightful information,  it took me a while to digest (I haven't slept for a while).  I didn't know that there were two kinds of CA until now.  I'd quiz you further but I think it would be a wee bit off topic.

     

    It's my own fault really, I know the limits of the lenses I'm working with and the exact circumstances under which they produce CA, but yet still downloaded a beta program in the field.  Which lets face it is a tiny bit on the silly side.

     

    Ah, you're right, it does makes sense; if they've only fixed one kind of CA for the other to follow.  I just need to find a way to roll-back to 6.6 (tried a few times to no avail), which is a shame as I do actually like 6.7.

     
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  • Currently Being Moderated
    Apr 11, 2012 5:33 AM   in reply to Jeff Schewe

    Jeff Schewe wrote:

     

    Longitudinal CA is the inability of the lens to have all three colors of light in the same critical focus...that is a HUGE difference in purpose and execution.

     

    I suspect that the first solution, Auto CA will be followed up by a solution for longitudinal CA at some point.

     

    Well, there is a solution for longitudinal CA in ACR and it is called Defringe. Essentially, it desaturates edges where it is most visible (as blue or purple fringing usually - because blue is focused a bit behind colors with longer wavelength on many lenses). Just it only has two options (+ off), so I hope it will be improved during timeline ...

     

    BTW, for my 400D kit lens, worst case scenario is focus a landscape to infinity and have some  trees nearby on the left or right side of the photo with sky as background. There are tons of PF on trees in that case. Focusing a bit close (say to 5-10m) improves this significantly without introducing too much blur, because blue focus point is moved towards the plane of the sensor. Anyone noticed this ?

     
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  • Currently Being Moderated
    Apr 11, 2012 6:10 AM   in reply to Vit Novak

    Vit Novak wrote:

     

    Jeff Schewe wrote:

     

    Longitudinal CA is the inability of the lens to have all three colors of light in the same critical focus...that is a HUGE difference in purpose and execution.

     

    I suspect that the first solution, Auto CA will be followed up by a solution for longitudinal CA at some point.

     

    Well, there is a solution for longitudinal CA in ACR and it is called Defringe. Essentially, it desaturates edges where it is most visible (as blue or purple fringing usually - because blue is focused a bit behind colors with longer wavelength on many lenses). Just it only has two options (+ off), so I hope it will be improved during timeline ...

     

    BTW, for my 400D kit lens, worst case scenario is focus a landscape to infinity and have some  trees nearby on the left or right side of the photo with sky as background. There are tons of PF on trees in that case. Focusing a bit close (say to 5-10m) improves this significantly without introducing too much blur, because blue focus point is moved towards the plane of the sensor. Anyone noticed this ?

    Purple fringing occurs with longitudinal (axial) CA when green (to which the eye and autofocus mechanisms are most sensitive) is in focus, leaving the red and blue components of the image out of focus. This is illustrated by Paul van Walree on his toothwalker website.


    Paul sums up: "Longitudinal and lateral chromatic aberration can both give rise to colored edges, but properties are different. Axial color causes fringes all around objects, whereas lateral color only affects tangential details. Axial color can occur at any position in the image, whereas lateral color is absent in the image center and progressively worsens toward the image corners. Axial color is cured by stopping down the lens, whereas lateral color is present at all apertures."

     

    http://toothwalker.org/optics/chromatic.html

     
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  • Currently Being Moderated
    Apr 11, 2012 6:22 AM   in reply to Bill_Janes

    It's essentially the same

     

    Actually, it's significant simplification. In reality, every wavelength has slightly different focus point and also, light in the middle of the image doesn't have the same focus point as the same wavelength coming from edges. These imperfections of the lenses can be called aberrations, but since they usually depend on wavelength also, word chromatic is added ...

     

    There was some lens design software available on the internet in demo version, I experimented with it several years ago, there were possibilities to draw various diagrams to show these things etc ... where this was much more understandable ...

     

    Figure 3 in above link is showing what I was talking about - amount (and color) of longitudinal CA depends on focus

     
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  • Currently Being Moderated
    Apr 11, 2012 6:22 AM   in reply to Jeff Schewe

    Jeff Schewe wrote:

     

    MJCRPJ wrote:

     

    I'd actually like it if they put them back (or improve  the function).

     

    Don't be surprised if Adobe adds some new functionality in the near future...

     

    I suspect that the first solution, Auto CA will be followed up by a solution for longitudinal CA at some point. You gotta know that the ACR/LR team is really hellbent on providing the maximum image quality but, they attack the various image defects in an incremental methods...not everything can be fixed in one fell swoop.

     

    If ACR adds correction for longitudinal CA to the already implemented automatic correction of lateral CA, the situation would be similar to what already is implemented in Nikon Capture NX2. For  preview of how this might operate, interested readers can look at this post on the Nikon web site.

     

    https://nikoneurope-en.custhelp.com/app/answers/detail/a_id/45733/~/wh at-is-the-difference-between-lateral-and-axial-chromatic-aberration%3F

     
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  • Noel Carboni
    23,488 posts
    Dec 23, 2006
    Currently Being Moderated
    Apr 13, 2012 5:11 AM   in reply to Lance Warley

    Well, I haven't found one single image the newer version hasn't done better than the old one, bar none.  Maybe it's my particular lenses, I don't know, but I haven't craved more control.

     

    Please, some of you with remnant fringing, put up some small crops showing the problem.  I think that would help everyone understand better.

     

    Some kinds of fringing need to be corrected a completely different way...  The blue or purple fringing as Vit noted above...  I have written actions for this.

     

    -Noel

     
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