Originally posted by Lowell Goudge The photo seems impossible. There is a combination of longitudinal CA but it cannot go purple, then green then back to purple.
Where does the image come from
It's from the PCMAG review
Pentax D FA 100mm F2.8 Macro WR Digital Cameras - Review 2016 - PCMag UK
For those interested the youtube link shows rather similar full on purple on some tree branches. I agree that the pcmag image is probably with a largish aperture but unfortunately there's no telling. I don't mind if ca is like that wide open but it's important that it goes away when stopping down.
Originally posted by stevebrot Yep...the difference is subject distance. It is not unusual for macro lenses to have mild LoCA at other than close focus that translates to alarming purple fringing (PF) with some sensors in high contrast light. One has to go to an apochromatic design such as the Cosina/Voigtlander 125mm Apo-Lanthar to be completely free of PF ($$$).
That's an interesting observation. All macro shots look near perfect, some of the longer distance ones less so.
It seems most of those who love it, and show excellent examples, (thanks norm etc) shoot the lens as it's intended. Macro or at least close up.
With a telephoto lens you can quite easily avoid sky in your photographs without making an effort. Hence never noticing the issue. For my use of the lens, compressed perspectives and details of architecture I'm very likely to have dark things against sky. I'm looking for a ff da70ltd replacement and the 100mm dfa looked like just the thing. Fringe away below f4 but clean up after.
I'll have to search for more samples
This ephotozine image from here
Pentax-D FA 100mm f/2.8 Macro WR Lens Review | ePHOTOzine follow link to see full size image. Looks ok at f6.3 some fringing around the frames but minor enough.