microscope vs. telescope eyepieces

There are lots of ads for high end microscope eyepieces with adapters for telescope use. Are there any fundamental differences in optical design criteria between them and comparable telescope eyepieces or is it just a packaging issue?

For example, is color correction, F/number, etc. equally important for both uses?

Bottom line: is a Zeiss 10X Abbe Ortho microscope eyepiece optically indistinguishable from a 25mm ZAO telescope eyepiece?

Unfortunately, there are many factors which govern the "use-ability" of most microscope eyepiece designs in telescopic systems. Perhaps the biggest differences/considerations involve "compensating" microscope eyepieces, which are designed to work with (to compensate for) optical characteristics & aberrations inherent to particular microscope objective designs. As such, many folks are wary of (or simply avoid) compensating -- a "K-Pl" eyepiece, for example (compensating plan/flat field). I don't have enough experience with compensating designs to offer any insight beyond that generalization. I'm sure there are compensating eyepieces which work perfectly well with scopes, but they certainly bear stricter consideration than non-compensating eyepieces. The Nikon 10x "CWN" eyepiece (from APM) may be a compensating design; I'm not sure.

I'm unaware of any current Zeiss microscope eyepiece which is specified as an Abbe orthoscopic. Most are indeed orthoscopic (distortionless), but their designs differ from the traditional Abbe design. For this reason, I wouldn't expect them to be indistinguishable. Not saying they're *not* -- just wouldn't expect it.

On the other hand, "different" may not mean lesser or worse. In the case of the 10x offerings from APM, for example, there are folks who find them to offer superior fidelity when compared to the 25mm Abbe Orthoscopic. Of course, this is another tough call, as a 25mm eyepiece yields lower mags, making critical observation of low-contrast planetary detail even more difficult.

Perhaps a few "guidelines" may be suggested:

-With microscope eyepieces (even moreso than with telescope eyepieces), the "try before buy" rule is essential. Luckily, there are folks like Markus who do much of the trial work for the rest of us.

-Most modern microscope eyepieces *not* designated as "compensating" will do well in most telescopes. Simpler designations such as "Plan" and "Wide Plan" are usually good bets. Nikon, Olympus, & Zeiss are the most-popular brands among stargazers. Kellner-variant & Konig-variant designs remain numerous & popular in the microscope industry. There are plenty older microscope eyepieces utilizing Huygenian & Huygenian-variant designs; these usually require extreme (long) focal ratios for good performance.

Hope that's not too much babble. :-)
Best wishes.
-Dan