Colour fringing

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Hopefully this is the correct forum for this - Is it just me who suffers from colour fringing? I doubt it, but it is a problem which I am finding frequently since using a Canon 5D 11. Vertical objects near the frame edges are the main areas for concern - a definite green and purple fringe on either side, even when using Canon L glass (a zoom though) and even at the optimum apertures of f8-11. I also get it with my Sigma lenses (also zooms). Admitedly, it is only noticeble when enlarging or viewing close up, but now I know it is there, it is bugging me to the point that I am considering selling all of my zooms and switching to primes, but will this sort the problem out? Its a big jump to make if it doesn't so what do you think?
 
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Jeff said:
it is bugging me to the point that I am considering selling all of my zooms and switching to primes, but will this sort the problem out? Its a big jump to make if it doesn't so what do you think?
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The short answer is probably not. Even some of the highly rated Canon primes like the 85mm f1.2L will exhibit the longitudinal (otherwise known as axial) aberrations that you're describing, indeed probably worse than a zoom when they're wide open. You'll also see it on Nikon primes like the 50mm f/1.4 and the 85mm f/1.4. It tends to be more noticeable on wider aperture lenses, especially in areas of high contrast when the lens is wider open.

It's very difficult to correct for absolutely in the design of a lens, though a true APO lens ought to do the best.

Lightroom 4 has a software tool to assist in removing Axial CA.
 
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Most lenses suffer a bit from chromatic aberration of one kind or another, including primes.

It's easy to get rid of in post processing, especially using the custom profiles in Lightroom that include loads of lenses of all brands. Also distortion and vignetting, too. Canon's DPP (free with your camera) is also excellent, but only covers Canon lenses of course.
 
Primes won't fix the issue. It can occur now matter how good your body and lenses are. As Hoppy says its a 10 second fix in lightroom
 
It's called Chromatic Aberration and is worth looking up on t'interwebs.

It's a function of bending light through glass. It can be minimised (at a price) but it will always be there to some degree.
 
two ways of fixing this, one lightroom or the lights, takes two seconds, the second is change how light interacts with objects, its just one of them things sadly, im sure its not that bad at a normal, only bad zoomed in
 
Siilver said:
two ways of fixing this, one lightroom or the lights, takes two seconds, the second is change how light interacts with objects, its just one of them things sadly, im sure its not that bad at a normal, only bad zoomed in
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I don't understand - can you explain what you mean by the second is change how light interacts with objects
 
boyfalldown said:
I don't understand - can you explain what you mean by the second is change how light interacts with objects
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when light, hits class it changes it simply, it makes it bounce and do different things giving the fringing
 
I understand what causes ca. And I assume you mean glass by class. What I don't get is your statement about changing how light is interacting with objects. Please explain
 
Not sure how lighting changes can affect a function of the glass, but Lightroom is great for this. It has a pretty decent list of lenses the it can autocorrect not only chromatic abbé ration, but also distortion.
 
Only thing I can think of is to avoid areas of high contrast, especially in detail, which will show up axial CA. If you can light to fill you minimise those parts of the image.
 
OK, thanks for the replies. Time to rethink and maybe buy Lightroom (I use Capture One Light at the mo.)
I currently get rid of it by switching to Lab colour, blurring channels a and b and then returning to RGB, followed by desaturating the offending colour (if possible) which, as you can imagine, is a bit of a fag when you have a lot of images affected.
 
Jeff said:
OK, thanks for the replies. Time to rethink and maybe buy Lightroom (I use Capture One Light at the mo.)
I currently get rid of it by switching to Lab colour, blurring channels a and b and then returning to RGB, followed by desaturating the offending colour (if possible) which, as you can imagine, is a bit of a fag when you have a lot of images affected.
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In Photoshop?

Assuming you've got a recent-ish version, Open the TIFF file from C1as RAW (File > Open > Format > [Camera Raw]) and you'll have access to the same correction tools as Lightroom. CS5 with ACR 6.7 gets the same features as LR3; CS6 with ACR 7 gets the same features as LR4.

The lens correction filter in PS gives you access to Lens Profile corrections and manual sliders for lateral CA corrections.
 
boyfalldown said:
I understand what causes ca. And I assume you mean glass by class. What I don't get is your statement about changing how light is interacting with objects. Please explain
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It was sarcasm you can't change light, its been like that milliions/thousands of years and it will stay like that till the sun burns out
 
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