Minimum focal lengths for ep's?

I've seen 2mm ep's offered- I got one a while back that was terrible. My question is how low do they go commercially, or by private individuals? Do the lowest FL ep's require premium primaries or will they work on run of the mill optics? Eye relief the ultimate limitation?

I'd also like to know which types (ortho, plossl, etc.) do best in the smallest FL ranges, and what makers can be relied upon to give quality product. Any vintage makers come to mind as well? Thanks.

Jess Tauber

Hi Jess,
I have the 2.5mm B@/TM$ planetary EP and it is pretty good. The eye relief is good and it seems to work well. I have not had a lot of time with the EP as the conditions have not be as excellent as I would like for this kind of power. The exit lens is the same size as the other planetary EPs too, which is nice. No small peep hole size lens that is hard to clean.
The 2-4mm Televeue zoom would be a good choice and you get 3 EPs in one too.

A Plossl and an Ortho would both be so short on eye relief that you would have to wear them as a contact lens.

Your best bet would be to get a 5X Powermate and stick with a reasonable length 10mm EP. Nothing under 7.5mm is practical in a Masuyama or Ortho for me, or under 9mm is a Plossl.