# Chromatic Aberration and Defringing



## Jimmsp (Apr 27, 2012)

I've been playing with the CA correction and defringing tools in LR RC2.
A couple of questions come to my mind.

1. Why would I not ever check the box for remove CA ? Shouldn't it always be on?

2. While I can see the result (in a few cases) of defringing, it isn't obvious to me how I optimize it. Can anyone point me to a good reference? 
I've tried a few searches and haven't really found anything that I like.


Thanks,

Jim


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## Jim Wilde (Apr 27, 2012)

Have you looked at Eric Chan's article on the Lightroom Journal piece announcing the RC2? See it here.

As to why the CA removal isn't turned on by default, I assume that it's processor intensive and so should only be turned on when CA is present.....but I'm only guessing.


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## Jimmsp (Apr 27, 2012)

Jim, 
Thanks for the Eric reference.
I missed this. Though on a first pass, it looks like I have a lot of learning and playing to do.

Re CA on - I'm running a decent processor. I may always turn it on; I'll have to see what the speed impact is.

Jim


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## Victoria Bampton (Apr 28, 2012)

Yep, you're quite right about the fact it's processor intensive, which is why it's not on by default.  If you don't find it to be a problem, you could update your defaults to automatically apply it.


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## Jimmsp (Apr 30, 2012)

Actually, in my recent tests, I find the overall performance is highly dependent on the number of photos in the folder that I load.
The more files loaded at the same time, the slower the performance is; especially with variable sliders for noise and sharpening.
I have tended to avoid some of these by starting from a number of noise presets that I generated on a test pattern.

In general, the best advice, often given here, is to adjust the variables in the order presented by LR.
This means saving CA until the end -- especially on a large number of photos.

I forget that LR is first a data base, then a file processor.


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