Canon 85mm f/1.8 Purple Fringing

toxic wrote in post #10290227
On very high-contrast edges, PF is normal with the 85/1.8. PF isn't measured in CA measurements, just blue/yellow lateral CA.

Not overexposing helps a lot. If you think it's still too much, try getting it checked out or try another one.

If it does, then apply it to the edges, not the entire image.

The CA removal features in LR 2.X suck. I can never entirely remove it via the Red/Cyan, Blue/Yellow, or Defringe options. Purple desaturation generally works, but I noticed it changes the WB of my images.

Is there a way to confine the desaturation to the edges?

Example photos are shot with apertures of this respective order: 1.8, 2.0, 2.8, 4.0, 5.6. CA is still noticeable at 4.0, and is well controlled, IMO, by 5.6

Mine is fine when stopped down to f/2.8. Otherwise, I wasn't able to figure out the way to get rid of it in PP. CA is a known issue with 85mm lens.
Wait till Sigma is out

Poe wrote in post #10290416
The CA removal features in LR 2.X suck. I can never entirely remove it via the Red/Cyan, Blue/Yellow, or Defringe options. Purple desaturation generally works, but I noticed it changes the WB of my images.

Is there a way to confine the desaturation to the edges?

I'm not that familiar with LR, but in Aperture 3 I use a color adjustment brush. Before that I exported to PS.

That looks like a lot more PF than you should be seeing...

aboss3 wrote in post #10290451
Mine is fine when stopped down to f/2.8. Otherwise, I wasn't able to figure out the way to get rid of it in PP. CA is a known issue with 85mm lens.
Wait till Sigma is out

Right. If the sigma has better control at f/2.8 like mine does at f/5.6, I'll probably get rid of this one and get the Sigma.

Poe wrote in post #10290445
Example photos are shot with apertures of this respective order: 1.8, 2.0, 2.8, 4.0, 5.6. CA is still noticeable at 4.0, and is well controlled, IMO, by 5.6

Yikes, that looks horrid.

Poe wrote in post #10290416
The CA removal features in LR 2.X suck. I can never entirely remove it via the Red/Cyan, Blue/Yellow, or Defringe options.

CA correction in Lr is not meant for LoCA. To properly correct LoCA you would require depth information, which current cameras cannot record. This is another reason why apochromatic lenses where invented.
And unfortunately neither the 85/1.8 nor its bigger brother 85/1.2 are apochromatic. Apo lenses require exotic elements and are very expensive.

tkbslc wrote in post #10290500
Yikes, that looks horrid.

Indeed. Granted that shot is f/1.8, but I expected better reduction by f/2.8 and I don't get it.

I've battled the purple fringe meanie on more than a few occasions

It seems related to focus .. you will see less (if any) PF on shots that are perfectly focused, and frequently a lot of PF in shots that are slightly OOF. So either live with it, fix it in post, be more careful with focus, or get rid of the offending lens. and when you do find an 85 1.8 or 50 1.4 copy with small amounts of PF, keep it

EDIT .. to Poe, that's the worst PF I've ever seen, something is certainly wrong.

CheshireCat wrote in post #10290696
CA correction in Lr is not meant for LoCA. To properly correct LoCA you would require depth information, which current cameras cannot record. This is another reason why apochromatic lenses where invented.
And unfortunately neither the 85/1.8 nor its bigger brother 85/1.2 are apochromatic. Apo lenses require exotic elements and are very expensive.

Interesting. So LoCA(purple fringing) is actually an aberation along the lens axis rather than the sensor plane axes?

mmahoney wrote in post #10290749
It seems related to focus .. you will see less (if any) PF on shots that are perfectly focused, and frequently a lot of PF in shots that are slightly OOF.

It is related to focus. More specifically, you will see magenta fringing when the focus is behind the subject. You will see a (less noticeable) green fringing when focus is in front of the subject. Problem is: in your shot there is not only the subject.
So, even if properly focused, something will be in front or behind the focus point... unless you shoot charts

I have found that converting a RAW file in DPP results in much less purple fringing than if I use Lighroom 2.X. I am not sure if DPP is doing an auto correction, or if lightroom 2.X is just exaggerating the purple fringing somewhat.

This is not LoCA. LoCA is green/purple fringing before and after the focus point. Even if these are not properly focused, they aren't OOF enough to explain all the PF, and LoCA is never that deep of a purple anyway.

mrfixitx wrote in post #10290863
I have found that converting a RAW file in DPP results in much less purple fringing than if I use Lighroom 2.X. I am not sure if DPP is doing an auto correction, or if lightroom 2.X is just exaggerating the purple fringing somewhat.

DPP automatically corrects for vignetting and CA with Canon lenses.

CheshireCat wrote in post #10290829
It is related to focus. More specifically, you will see magenta fringing when the focus is behind the subject. You will see a (less noticeable) green fringing when focus is in front of the subject. Problem is: in your shot there is not only the subject.
So, even if properly focused, something will be in front or behind the focus point... unless you shoot charts

Will the fringing occur not at the exact object distance but within DOF or outside of the DOF entirely?

I haven't done any micro adjustment to this lens. I suppose I should try that as well as shoot a flat surface? (Just printed off an ISO 12233 chart to use).

Poe wrote in post #10290809
Interesting. So LoCA(purple fringing) is actually an aberation along the lens axis rather than the sensor plane axes?

Indeed.
"Lo" stands for Longitudinal. Along the lens axis.