70-200 2.8L problems with CA

Hey all,

I recently purchased my first L lens and I've been extremely impressed with it but I'm worried my copy might be a little off. Is this amount of CA acceptable wide open under extreme conditions?

80mm f/2.8 iso400 1/500 +1/3ev

Full size:

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dear noname,

the sky looks pretty blown out, i think that's pretty acceptable for those conditions. it's pretty extreme i think but it wouldn't hurt to do a few tests.

holla at your boy

The first shot looks absolutely fine.

The first shot is also the version a person would normally look at.

I've always gotten a kick out of people who are concerned with slight problems at 100% crop. The only time you'll look at a 100% crop is when you're looking for a problem. In my book, if I can't see it when the picture is normal size, I don't worry about it...

The good news is...that shot is just about the best way to show CA, so it won't get much worse than that That's not bad at all, especially when viewed properly. I don't see the CA at all in the first image!

Greetings,
Even the best of lens will exhibits CA under such extreme condition. View at normal size, its very acceptable. So its normal. Enjoy...

Noname I would do more tests on this. As the Jingster said your pic is an extreme case and the CA is clearly aparent for a subject that's so close to the focus point. A good test case would be to photograph a subject with dark leaved trees in the background that are against a blown sky. The OOF leaves (by virute of distance from the focus point) will more than likely display CA but it's just a matter of gauging how much is acceptable.

wow, thanks for the input people.. I will definitely be testing this out some more tomorrow and jing, mind if I compare my copy to yours? :P

@Steve Parr, I agree that if my pictures were only going to be viewed on the internet (@333x500) then the above image would be acceptable

sure thing man, we can start that sooner than you might think

the lens is fine

I don't see any CA in the crop, only fringing from difraction around the hair.

noname wrote:
wow, thanks for the input people.. I will definitely be testing this out some more tomorrow and jing, mind if I compare my copy to yours? :P

@Steve Parr, I agree that if my pictures were only going to be viewed on the internet (@333x500) then the above image would be acceptable

I use the same lens as the one you did for that photo. I've printed as large as 11X14", and CA doesn't seem to be a problem at all. I guess, if I printed a 100% crop at 11X14", that would change. In the meantime, though, I've not seen anything offensive from printing larger photos...

As others have told you. From Photozone:

"Chromatic Aberrations
The lens also showed an very good behavior regarding chromatic aberrations (color shadows at harsh light transitions) peaking at about 0.6 pixels on the average at the image borders - nothing to worry about by most standards."

Yup, there is some CA there, I don't think it's excessive, considering it's at f2.8 and you are shooting strands of black hair up at a cloudy sky, which is usually the worst case scenario to induce CA.

My opinion also... this isn't CA, but the dreaded purple fringing, which is caused by excessive contrast between the dark/light areas, and is peculiar (AFAIK) to digital sensors.

I would say 'nothing to worry about!'