What is this and why am I getting it?

[SARtech]

Hi... need advice.

I would like to know why sometimes I get this blue-purple edging on captures. The images below are 2 captures I got this weekend. I have uploaded each shot how it looked RAW and after PP. In the RAW samples I circled some of the spots I am speaking of.
I don't seem to get this when there is more contrast between dark and light as you can see in the seagull shot.
Please tell me what this is called and how I can eliminate getting it in the first place.
These were shot at 200 ISO - 300mm (Canon 70-300) - Canon Rebel Xsi - handheld

[mwfanelli2]

It is called "purple fringing" and is normal for all lenses. Small lenses as found in P&S can be problematic at times. DSLR lenses tend to have a smaller effect.

For this lens, try shooting away from bright light. You can fix this problem with a product called Color Mechanic after the fact. But that might be an expensive solution for a problem that won't occur most of the time.

[SmartWombat]

I see it more markedly on out-of-focus contrast edges. So getting good focus is critical.
As is preventing shake; I'm not sure why there should be a stronger blue fringe than any other colour when I have camera shake, but it seems to be really apparent on highlights.

Lightroom is pretty good at removing this too, click "Defringe all edges".
But the more expensive (and better) solution is a better lens.

It's not just the lens, the same lens on different bodies will have different effects.
You shouldn't be surprised I see it more on the 20D that the 1DsmkII or 1DmkIIN.

Purple fringing normally isn't this blue colour (it's purple) and I get it a lot with the 20D next to over exposed highlights. It's a sensor feature that no lens can fix - even "L" lenses.


The first image (IMG_6103) with the twigs looks soft all over, you can't sharpen an out of focus image.
Except the twig on the left that's in shadow and looks black, that looks sharp. So maybe it was focussed behind the bird.

Second image (IMG_6105) the top and bottom of the branch look soft, I think it's just out of focus.
Both of those look over-sharpened though - probably as part of the raw to jpg conversion and resizing for the forum.

I've attached your image processed in Lightroom; slight blue and red chromatic aberration adjustment, and defringe all edges setting and it's not too bad. Working on the original raw file would give better results.

[SARtech]

Thanks Paul and mw.

I don't think it's the focus. I manually focused on the eyes.... looked good and got the "beep" too.
My bad though... I forgot to mention that these samples are cropped. Could that be another reason why? Below is the whole frame.

Unfortunately, at this time I am stuck with the equipment I have and I only have Adobe Photo Elements. Really wish I could afford a larger lens. I wouldn't have to crop as much.

So... the only way not to get this in the first place is try to avoid bright backgrounds?

[SARtech]

Thanks again you guys. I've been working on those 2 photos and think this is the best I can get. Think they are ready to post in Nature & Wildlife!

[freygr]

Form just looking at these photos, it looks to me like DOF problems the AF is focusing on the big branch and data from the EXIF data, the aperture is F7.1 @ 300mm gives less than 3 feet in focus at 30 feet.

[livin4lax09]

it's actually called chromatic aberration

http://en.wikipedia.org/wiki/Chromatic_aberration

pretty common problem in digital photography, a lot of the new lens coatings are implemented to prevent this from occurring.

another good link on the topic

http://www.digicamhelp.com/taking-ph...lity/fringing/

[SARtech]

Thanks for the links Brent, and GRF... I manually focused these on the eyes. I'm just starting to realize I have a crappy lens. (too short and not expensive enough)

[BlueRob]

All said above is true and very valid and all the factors merge in the results.
I can only add that some lenses deal much better than others.
What 70-300 lens are you talking about.? anon has several on that range.

[SARtech]

It's a Canon EF 70-300mm 4-5.6 IS USM

[BlueRob]

It's a Canon EF 70-300mm 4-5.6 IS USM

Hope you find this interesting...the pros and cons on this particular lens....for what I see in your images is the "standard" softness in the long range of the zoom plus the others aspects mentioned above.

http://www.the-digital-picture.com/R...ns-Review.aspx

[mn shutterbug]

I recently purchased a used 85/1.8 and the one and only time I tried it outdoors, the chromatic aberation was widespread. I was shocked how bad it was. However, I bought the lens for indoor low light situations, at which it performs beautifully, so it doesn't bother me.