>>Mike, my guess is that keeping the entrance pupil stable ensures that
>>is no undesired change in subject size on the in-focus image. But
>>mind that I didn't even complete the sophomore year of my focal
Thanks for thinking about that. Makes perfect sens ebut I wonder how
much the image size changes using a focusing helicoid vs that
The alignment software seems to choke if the framing changes too much.
Perhaps a set up using the Z. 21/2 could be worked out
with an extension tube and a RRS screw driven precise macro rail. I
don't know how many mm a turn of the helicoid is, but one could
possibly keep the entrance pupil quite stable. one would have to remove
the ext tube of course for infinity
focus and keep the lens entrance pupil in the same spot anyway.
It would be quite fussy.
Not a fully fleshed out out idea but I might try it if it can be worked
out and is practical.
Themed Olympus Photo Exhibition: http://www.tope.nl/