One of the very few lenses I've shot with that has virtually no C/A wide open or below 2.8 is the 200 2L and artificial fluorite is a big reason for that. To add that to an 85L the price would probably double but probably fix the problem.
Probably more... real APO lenses are very expensive.
But knowing a few things, we can minimize this issue with "cheaper" achromatic lenses like the 85/1.8 (and 85L/1.2):
- There are two type of fringing, purple and green. Purple being usually the most noticeable for obvious reasons.
- Both purple and green fringing are absent (ZERO) in the focus plane. And they increase linearly with a point's distance from the focus plane.
- Purple fringing affects points before the focus plane.
- Green fringing affects points behind the focus plane.
Now, it is often possible to keep critical subject points (white or specular highlights) in the focus plane. If this is not possible (subject tilted), try keeping them behind the focus plane as green fringing is usually less noticeable.
In the girl example previously posted, focusing on the white headband would have probably solved the problem.
In the train example, waiting for the train light to pass behind the focus plane would have solved the problem.
I must say I am totally happy with my 85L, and i almost always use it wide open. The very few times I see some noticeable fringings, a quick pp session will take care of it
Never tried the 85/1.8 though, so YMMV.