My quest for obscure information on Japanese optics continues. The subject of this thread is to ask who supplied Tani-san with glass?
In an older thread, Sheldon Faworski stated that Carton supplied Tani with glass (and Towa, Vixen, Celestron, Edmund Sci., Tele-Vue, etc) and he, of all of us, should know because he sold Carton stuff.
CN wisdom suggests that Carton stamped some of their eyepieces with a "Circle-Minus".
I collect volcano tops, and recently spent a pleasant evening with these two:
On the left is a "Circle-Minus", and on the right, a "Circle-T". But they are utterly different! First difference noted is the bevel, knurling and location of the eye lens in the volcano tops. The engraving is also different. And heck, the view was utterly different, with the Circle-Minus providing a much crisper field stop and view right across the slightly larger FOV than the "Circle-T", and the point at which they focus differ by several millimeters. Some of this can be explained by the different construction when viewed from below the eyepiece:
These are two very, very different eyepieces.
I have not (yet) taken them apart, so cannot tell if I am looking through an Abbe ortho or symmetrical ortho ("Plossl-lite").
- If Carton supplied Tani with glass, then Carton may have had more than one formulation for orthoscopic quality available to resellers.
- If Carton supplied Tani with glass, then Tani may not have always selected the premium formulation.
- If Tani did pick and choose quality, then "Circle-T" is no guarantee of a premium orthoscopic.
- If Tani did pick and choose quality, then they may have had more than one source of glass.
Vintage volcano top orthos are no guarantee of premium vintage eyepieces. I suggest this conclusion may extend to Kellner designs as well.
Edited by hottr6, 10 March 2016 - 04:07 PM.