12 Replies Latest reply: Apr 13, 2012 5:11 AM by Noel Carboni RSS

    Where are the CA sliders in ACR 6.7 beta?

    Lance Warley Community Member

      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.

        • 1. Re: Where are the CA sliders in ACR 6.7 beta?
          JimHess MVP

          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.

          • 2. Re: Where are the CA sliders in ACR 6.7 beta?
            Lance Warley Community Member

            It sounds like we lose control if the only option is the automated option.

            • 3. Re: Where are the CA sliders in ACR 6.7 beta?
              JimHess MVP

              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.

              • 4. Re: Where are the CA sliders in ACR 6.7 beta?
                MJCRPJ

                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.

                • 5. Re: Where are the CA sliders in ACR 6.7 beta?
                  Jeff Schewe Community Member

                  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.

                  • 6. Re: Where are the CA sliders in ACR 6.7 beta?
                    MJCRPJ Community Member

                    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.

                    • 7. Re: Where are the CA sliders in ACR 6.7 beta?
                      Lance Warley Community Member

                      Thanks, Jeff. That's far more than I knew about CA.

                       

                      My "simple" goal to is to have no CA, which I think of as "fringing." The fringing is small but noticeable, especially in contrasting areas like a mountain against a sky. Very hard to get rid of.  Very annoying.

                       

                      I use a Canon 5D2 with a Canon 17-40L and a Canon 24-105L. I'm hoping I don't have to spend money on different lenses to avoid this problem.

                      • 8. Re: Where are the CA sliders in ACR 6.7 beta?
                        Vit Novak Community Member

                        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 ?

                        • 9. Re: Where are the CA sliders in ACR 6.7 beta?
                          Bill_Janes Community Member

                          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

                          • 10. Re: Where are the CA sliders in ACR 6.7 beta?
                            Vit Novak Community Member

                            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

                            • 11. Re: Where are the CA sliders in ACR 6.7 beta?
                              Bill_Janes Community Member

                              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/~/what-is-the-difference -between-lateral-and-axial-chromatic-aberration%3F

                              • 12. Re: Where are the CA sliders in ACR 6.7 beta?
                                Noel Carboni Community Member

                                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