Marty,

In case you weren't aware, you only need to wear glasses when observing if you have astigmatism. Even then, with mild astigmatism many observers find they don't need glasses when using higher powers because the exit pupil is small enough that only a small part of the cornea is used.

However, if you have astigmatism bad enough to need glasses when observing, you'll want the 20mm eye relief of the Radians. Some of the longer focal length Naglers have good eye relief so don't rule them out before checking.

Another option is a Nikon eyepiece. I got one as a compromise between a Nagler and a Radian in the 10mm range. It has a 70 degree AFOV, 20mm eye relief, and is very contrasty and sharp right to the edge. I've only been able to use it once since I got it, but the field is very flat with no pincushion distortion and there is no kidneybean blackout - very comfortable to use. I need to use it more on bright objects to be sure, but it seemed that there was little to no color fringe at the edge, which is common with Radians.

The downside? It is a modifified microscope eyepiece with an adapter so it requires a lot of in-travel to reach focus. This is one of the big pans against the 31mm Nagler (which I also have and love!), and the 10mm Nikon needs to go in about .25" more. But, if you're going to build your own scope, you can plan this into your design. I built my own scope with the 31mm Nagler in mind plus a bit of sludge and I'm glad I did 'cuz the Nikon just makes it. Good luck.

Doug Tanaka