Olympus Zuiko 17mm vs Panasonic Lumix 20mm

I look for CA (or, rather, can't help but notice it), and while I mostly used the 20/1.7 for low light mono work, I've never really thought about CA with this lens.   Every lens can exhibit it to a degree, but this one never stood out to me in this regard.  So I just looked back in the archive for bare branches against a nearly blown out sky in a corner of the frame.  The aperture was 4.5, viewed at 400%.

LaCA is minimal.  LoCA (purple blooming/fringing) is more significant, but not at all like the extreme LoCA that's been recently discussed involving the OM-D and the Pana 7-14 / 12-35 lenses.  It's just 'evident' where would would expect CA to show, where the other lenses exhibited it rather extremely (which might be putting it mildly).

The manual eyedropper chose a correction of Purple Hue 30/43 Amount 7, Green Hue 23/34 Amount 3.  Because its choice can sometimes be extreme (spilling over into unwanted areas), I have a habit to reduce the amount to some degree (here I set Green amt at 2, Purple amy to 5).

Eliminating the LoCa, the LaCA that remained was only barely evident, but the CA checkbox correction was better than my eyes, and it showed the improvement for perfection.

An import preset with the CA box checked should be used by default on all OM-D images (it doesn't hurt if not necessary).  Where LoCa shows itself, the eyedropper is an easy fix.  If these adjustments are done right off the bat, then one can copy these settings and stamp the rest of the images taken with the 20mm in that series.  One could save the LoCA adjustment for different apertures as presets too, to make slightly less 'work' for future imports with the OM-D/20mm.

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...Bob, NYC
http://www.bobtullis.com
/"Well, sometimes the magic works. . . Sometimes, it doesn't."/ - Little Big Man
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