What's this and how do I get rid of it

G-Dubs · 2 May 2011 at 15:51

New to the art so please excuse as I guess this is a really obvious one to all you chaps.

I sometimes get a purple (sometimes green) line appearing around the edges of structures in images.

What causes it and how do I stop it?

I'm using a 60D and get it on each lens I have.

In the example below it can be seen on the edge of the plastic water bowl and the metal frame in which it sits.

All help appreciated.

Shadowness · 2 May 2011 at 16:00

Purple fringing, or chromatic aberations.

It's inherent in all lenses, but worse in cheaper ones.

Use photoshop or something similar to remove it.

Stupot_ · 2 May 2011 at 16:03

What he said. It tends to appear on areas of high contrast. What lenses do you have?

Andy90 · 2 May 2011 at 16:12

If you have a Canon 60D, then you should have a disc that came with the Camera. On that disk is a program called Digital Photo Professional. You can reduce the Chromatic Aberration in your photographs in that program.

Also make sure you're shooting in RAW format rather than JPEG. Think of it as the Digital equivilent of a film negative. The RAW file has no preocessing applied to it and you can tweak colour, contrast, noise and aberrations etc., within Digitial Photo Professional before exporting them as Jpegs.

DPP is rather basic, but its a good place to start, once you feel confident with that program you could then move onto more advanced programs such as Lightroom 3 or Photoshop.

You can find a number of DPP Tutorials at

http://www.learn.usa.canon.com/galleries/galleries/tutorials/dpp_tutorials.shtml

Andy90 · 2 May 2011 at 16:14

double post.

D.P. · 2 May 2011 at 16:33

More expensive lenses usually have less CA, even so it is still common in varying amounts.
The CA can be removed, but at a cost of reducing apparent edge sharpness.

feriso · 2 May 2011 at 16:42

D.P. said:
More expensive lenses usually have less CA, even so it is still common in varying amounts.
The CA can be removed, but at a cost of reducing apparent edge sharpness.

Not neccesarily, Raymond's 85/1.2 has quite noticable CA.

Shadowness · 2 May 2011 at 17:08

That's because it has such a large aperture. My Sigma 85mm 1.4 has noticeable CA too.

D.P. · 2 May 2011 at 18:08

feriso said:
Not neccesarily, Raymond's 85/1.2 has quite noticable CA.

Yes, as I said it is usually present in varying amounts.
Cheap kit lenses have the highest CA, a good normal zoom like a 24-70 2.8 has very low CA, as do moderate primes. Wide angle lenses are often worse, and very wide aperture lenses often have high CA due to the design.

HypnoToad · 2 May 2011 at 18:09

is it true that some camera bodies can eliminate CA totally when it saves the jpeg?

Shadowness · 2 May 2011 at 19:14

They try to remove it, I think my D3 has that feature. But I turn all in camera processing off anyway.

G-Dubs · 2 May 2011 at 20:37

Cheers Guys

That DPP was a nice link

I can see myself spending a bit of time there