Looking for an eyepiece in the 16-22mm range for an Astroscan, to be
used with eye glasses.

It should be fairly small in size and have 20mm eye relief.

The 20mm Orion Expanse looked good at first--- right size and e.r. --
but it's horrendous at the f/4.2 of the 'Scan (only the center is sharp,
the rest is pure seagull, comets, nauseatingly distracting).
Works pretty well in an f/5.4 dob, however.

Tried a 17mm Burgess Optical WA in the little red ball wonder. Quite
nice, better outer fov than the 20mm Expanse, usable in that regard, but
e.r. really not sufficient.

What's the size of the 18mm Radian? I couldn't find specs on its length
at the Televue sight.

Any recommendations?

Larry Stedman
Vestal