01-28-2019 06:17 PM - edited 01-28-2019 06:19 PM
IS has nothing to do with focus. It simply moves the image around on the sensor to compensate for lens movement, as determined by internal aceleration sensors.
CA is a problem anytime you have a non-flat piece of glass. It is the same reason prisms can split light into a spectrum.
01-28-2019 06:21 PM
"The lack of sharp focus makes me think the IS isn't working."
That is really is no indication. IS doesn't make a lens any sharper. It makes you sharper. I believe your only recourse is to have someone, Canon, check it out as you will always think something is wrong even if it isn't.
01-17-2020 05:13 PM
Ive been having alot of purple and I can fix it in PS, although not so great at times, but all its dong r removing those colors from the entire photo. That results in 1.) then I very light(white) halo instead, which isn't the worst, but 2.) removing color from places you dont want. What can be done so it doesn't happen to start with? Seems like its just, not shooting where theres alot of dark to light(possibly more so near the outside) or zooming in. Im using an EOS R, but Ive never had a problem with past cameras, so I thought I may just be photographing badly ):