I have earlier reported on my problems focusing macro lenses at infinity due to a too steep pitch of the helicoid.
http://forum.luminous-landscape.com/index.php?topic=110587.msg930570#msg930570, reply #3.
Now I'm trying to specify measures for a custom-built helicoid. I go for a helicoid with a fixed camera mount (E-mount) and interchangeable short flange adapters for different SLR lenses.
These lens adapters should be optimised so that the whole system focuses at infinity - with some tolerance BEYOND.
Question: How large should this tolerance be? Will 0.5 mm be enough, or need it be 1.0? Not more probably? Or should it be spelled out as a percentage of the travel of the helicoid? And if so which one?
At this time, I have asked for offers from S.K. Grimes and
http://www.adrianololli.com. If anybody knows of a good photo machinist in Europe, preferably Germany, please let me know. Griturn in the UK does no longer seem to offer custom building.
Thank you for your advice.