Bernhard Vogl wrote:
> Apparently the focusing error is introduced by using the adapter (at
> least the M42->Nikon/Canon adapters, don't know about the "native" mounts).
> This may explain why some have problems why others don't.
This was my impression, too. When I had my first fisheye I was
astonished how small the focusing extension was. The Zenitar focuses
from infinity to 30cm in 1mm (0.3mm for a 8mm Peleng from infinity to
22cm). Hence a minor difference in the adapter (which will be not
recognizable with a longer focal length) can cause severe defocus.