We had already discussed the data from Roger at Lensrentals.
http://www.lensrentals.com/blog/2013/09/there-is-no-free-lunch-episode-763-lens-adapters
Seems lenses with floating elements seem sensitive to the rear element
being too close to the sensor with degradation of corner performance
and CA.
Not sure why that is. Too thick adapter result in losing infinity focus
but not other aberrations. This makes it an issue with expensive
adapters as it would be better to shim the lens (with an easily
reversible method) than buy a bunch of expensive adapters. Or obviously
shim a cheap adapter for each lens. This seems more of an issue now
with mirrorless cams as too thin an adapter does not result in any risk
of hitting the non-existent mirror.
OM lenses seem to have quite a good hard stop at infinity (and I think
Zeiss ZE) but Canyon seems to go past infinity a tad normally, I think.
http://www.davidclapp.co.uk/blog/view/setting-up-camera-adapters-tutorial
The new twist I learned is that the floating element lenses are the
most sensitive to thin adapters. Given the depth of focus at many
apertures, one might think this is a non-issue but has been confirmed
on many occasions now.
On another note on possible digital back for OMZ lenses, have seen many
night images now with the A7II--sensor flare much better but still
there.
sigh.
Adapt with care for best performance, Mike
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