[Leica] Zeiss Ikon Focus Shift

[jbilin at axionet.com (Jacques Bilinski)]

> a mechanism to correction
> for focus shift with aperture, which would require some sort of linkage
> between the aperture ring and the focus ring - not something I have
> heard of before.
>
I've never heard of this either, but on an AF camera like the Nikon or EOS
it would not be too difficult as the camera is doing the foccusing and
already knows the f stop and the distance. A lens with a lot of focus shift
implies a loss of sharpness at wide aperatures as all the light rays present
at small aperature are also present at a wide aperature and would be
focussed at a different distance.