Carl Zeiss Jena offered various eyepieces. But the types are only classical:
huygenian and orthoscopic eyepieces would built for the Telementor. No such new types like plossls or widefields... And
the .... has 24.5mm or 0.96 inches in diameter.
The most simplest eyepiece-type is the huygenian: It is the type with only two lenses. The focal lengths are 63mm, 40mm, 25mm
These are eyepiece, who are good for sun-observing and solar-projection, because they are not pasted (and for this
you need - because of the enormous heat - not cemented lense-elements!)
And, my opinion: These eyepieces are good! For usage in the low and middle magnification range (~ 70 x), they are conveniant and
you get nice sights with your telescope.
For sure, the most huygenian - eyepieces are cheap ones, but not these from Zeiss-Jena! With these you get nearly edgesharp and
Of course, better are the orthoscopic Eyepieces. Using them, you will get a sharp and high-contrast view, also in higher
magnification-range. But there is a problem: As the eyepieces would no more be produced, they are very rare and difficult
to get. And you (particularly in the U.S.) have to pay absurd and exorbitant prices for these eyepieces.
There are these focal lengths: 40mm, 25mm, 16mm, 10mm, 8mm, 6mm and 4mm. So they are for use in all magnification ranges.