poor thread fit (slight mismatch in sizing i suspect, to summicron 35-M and 50-M. (I wanted to use this as a screw on cap really and to have lens ready to shoot in "emergency) when there is not time to unscrew.
It is plain glass. There is no coating. Reflecting everything just like a window glass. Not impressively thin either. surface smooth and flat though.
Not usable
sharp to corners at f4 !
no color shift even at 16mm, minimal vignetting.
For me replaces not only its range of 16 to 21, but 24 and 28mm as well as it is so sharp that i can easily crop my image from 42mp sony a7rII and still have razor sharp image for a 16x20 print. very compact for travel and street architectural photography
It is about half the size of anything in that range in sony e-mount offerings.
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Leica L39 M39 Mount Lens to Sony E mount NEX 3 C3 5 5n 6 7 Adapter Ring L39-NEX
May 16, 2018
ideal tool to use Leica lenses on Sony
solid fit, no wiggle. allows infinity focus. The lens position may be adjusted with loosening the screw - very valuable feature when mounting vintage leica lenses on sony camera.