Well as my interest has been sparked by old eyepiece design I have been doing a lot of digging and research.
Some folks may find this useful as an eyepiece tool, it clearly states the name, year, and F ratio the eyepieces were designed to work at, although not always strictly, like ball eyepieces can work down to F10 fine.
When thinking of making my own ball eyepiece, and also making my own Dollond eyepiece. I remembered I had some Japanese eyepieces that came with my Towa in 0.965" variety. One is a symmetrical Ramsden eyepieces in 4mm, 6mm and 9mm Huygens, one is what I take to be a Kellner in 22mm ( has the designation of Ke22mm ) .
I also have what I think is two microscope eyepieces which are the same, which I'm not even sure who made it? It has 6X on it. The focal length of a microscope is 250mm. So 250/6= 41.66. So it would be equivalent to 41.66mm focal length eyepiece.
Needless to say I have ordered a 1.25" to 0.965" Baader adapter. So I can try these old eyepieces out in all my telescopes. The glass in all eyepieces look spot on, no scratches whatsoever, and I had cleaned them years ago.
Below is a photo of the eyepiece, if anyone can help me identify it?
Edited by Dave1066, 11 March 2018 - 12:20 PM.