paulkaye wrote in post #12986330
Hi - I have an 85mm 1.8 which is a great lens in many ways - except for one thing; purple/green fringing on out-of-focus highlights (LoCA/bokeh fringing). I use both Bibble and Photoshop/ACR and have yet to find a satisfactory way of getting rid of it. Does anyone have any tips/tricks?
LoCA's can be very difficult to handle. The defringe setting might help a little, but the sliders are unlikely to be much use. If the issue is really bothersome you can try desaturation. Either globally desaturate if your image allows for it, or you can get down and dirty with layers/masking in Photoshop.
Hardcore wrote in post #12986363
Maybe the CA isn't as bad on the Sigma 85mm but I usually go manual corrections, then go down to CA and put "defringe" to All edges or highlight edges and play with the sliders to reduce the CA. Works well enough for me. For sure there would be better ways in photoshop but I haven't bothered with it.
The Sigma is pretty bad in the LoCA department (like most ultra-fast lenses). If you shoot wide open or close to it with high contrast items in the foreground and/or background the problem should be pretty obvious. You will see magenta fringing in front of the focal plane and green fringing behind it. The CA sliders won't do much since they are designed to handle lateral CA's.