20mm on OMD concerns

I second that : the 20mm F1.7 is an awesome performer. It is one of the sharpest lens offered in MFT mount. And all that in pancake shape and with a very fast aperture. It was a must have lens for a long time. Nothing can beat it for the portability without compromising on IQ.

Yes, it has some drawbacks :

Some say it is slower to focus, but it ay be somewhat slower, but nothing to worry about. It won't results in missed shots. It may hunt a little in lw light, bt not if you use the focus and reframe technique and point the target at a well lighted point located at the same distance as your subject.

Yes, it can show some banding, but nothing dramatic : it does only strikes in when you are shooting at high ISOs (3200 and up), will at first be faint and increase with increasing ISOs. It doesn't show up in all high ISOs pictures, but you will encounter it. It will only become apparent in uniforms and rather dark zones of the picture. It will often be easy to correct : just desaturate and darken that part of the picture, or make use of the demoire brush in LR (Other softwares probably offer something similar), or the Gaussian blurr. Some people have posted images where they have emphasized the problem by lifting shadows exagerately, adding contrast, saturation and sharpness to make their point. So yes there is a problem but it is overbloated.

The Panasonic lenses are software corrected for chromatic aberrations on a Panasonic body, but not on an Olympus body. Since Panasonic uses software to correct CA, their lenses ar more prone to it than Olympus lenses. So yes, in some situations you are more likely to see it, but ca can also be easily corrected if you shoot raws and also if you shoot jpegs (but that will involve a little postprocessing. Note that you won't see it in all pictures, you will see it when you have dark objects against a bright background. The longitudinal purple/violet fringing isn't corrected by Panasonic either (only the green/ red and blue/yellow ones lateral fringings are corrected).

To sum up : go for it, it is a very nice lens.

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rrr_hhh