Problem with chromatic aberration with my new Canon EF 85mm f/1.8

[sungkhum]

I just got my new Canon EF 85mm f/1.8 and tested it out. I was dissappointed by the amount of chromatic aberration it produced at f/1.8. Does anyone else have this issue, or did I get a bad lens?


[img]/resized-image.ashx/__size/550x0/__key/CommunityServer-Discussions-Components-Files/8/2664.ca_2D00_85mm3.jpg[/img]


[img]/resized-image.ashx/__size/550x0/__key/CommunityServer-Discussions-Components-Files/8/6082.ca_2D00_85mm.jpg[/img]


[img]/resized-image.ashx/__size/550x0/__key/CommunityServer-Discussions-Components-Files/8/6355.ca_2D00_85mm2.jpg[/img] This is at 100%





I was expecting better, but perhaps that's just the way it is...or perhaps the lens needs to be returned?





Thanks for your help,


Nathan

[thekingb]

I wonder if this is a function of shooting at f/1.8 in broad daylight -- especially with the sun shining on the statue. It's hard to shoot that wide open in broad daylight. I seem to remember reading some review or article about this at some point....


I just scrolled through hundreds and hundreds of photos taken with my 85 f/1.8 at either f/2 or f/1.8 and could find only one with noticeable purple fringing -- a shot of the moon at f/1.8. There's a serious purple ring around the moon, not to mention some flare. But the vast majority of my shots at that wide of an aperture are in lower light conditions.


[img]/resized-image.ashx/__size/800x800/__key/CommunityServer-Discussions-Components-Files/8/0160.IMG_5F00_8329.jpg[/img]

[neuroanatomist]

Hi Nathan,


The Canon 85mm f/1.8 does suffer from a fair bit of longitudinal CA (LoCA). LoCA is the purple-green fringing at high contrast transitions, distinct from lateral CA in that the longitudinal type is evident across the frame, while lateral CA is worse at the borders andred/blue in color. Unfortunately, while lateral CA is pretty easy to correct in post (done automatically by many software packages, including DPP), LoCA is not easy to correct.


Bryan doesn't mention it in his review of this lens, but they show it in the [url="http://www.photozone.de/canon_eos_ff/419-canon_85_18_5d?start=1]photozone.de review of the 85/1.8[/url]. Pretty much all very fast lenses (f/2 and wider) suffer from some degree of LoCA. I'd say what you're seeing is normal.


FWIW, the LoCA is really the only major flaw of the 85mm f/1.8, and as I said, it's a flaw shared by all fast lenses (even [i]much[/i] more expensive ones). IMO, the 85mm f/1.8 is one of the best values in the Canon lineup - great IQ at a great price.


--John


Ps. you can see the LoCA in a test composite I made, comparing the 85mm f/1.2<span style="color: #ff0000;"]L II with the85mm f/1.8 (the 100% crops at the bottom show pretty clearly why LoCA is also called bokeh fringing). It's present with both lenses, slightly less strong with the 85L, but still definitely there.

[wickerprints]

In a nutshell: yes, it is normal for this lens, as well as almost any fast-aperture design (i.e., faster than f/2). It

[sungkhum]

Ok, thanks - very helpful!


I love the lens so far - super sharp!


-Nathan

[M_Six]

It

[sungkhum]

Yeah, I wish Lightroom 3 did a better job with it - but it barely changes anything (though it is a little better when I don