Unknown eyepiece fitted to 1.25" aluminum adapter

Auction No.:
Current Bid:
High Bidder:
Paul Targonski
Bid History:
1 Bid
Spokane Vly, WA - US
Andy Sedlacek
03/12/2019 08:18AM
03/19/2019 08:18AM
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So this eyepiece came to me in a bundle in late 2016 and I've used it here and there, but for the most part, kept trying to figure out who made it. There are no makers marques, but there are (3) unusual holes lined on the side. Interesting....

First off, this is not a cross hair ocular. 

The homemade aluminum adapter is for 1.25-inch use; yes you can use this in your telescope. However, the eyepiece on its own has a barrel diameter of 1.00-inches. This is puzzling to me because most microscope eyepieces are .912-inches. This is the only eyepiece barrel of this size I have ever come across.

Construction is milled aluminum and brass, and weighs 1 ounce. If mounted with the solid aluminum adapter, 2.4 ounces.

Field of view is right at 38-deg with an exit pupil of 8mm. Optics are fully coated. The eye relief is going to be tight for eyeglasses. Focal length seems to be in the 20mm-18mm range.

Optics are in great to great+ condition with no real issues to mention. Cosmetics are excellent.

I am unsure if this is a Ramsden or a Huygens, but it is not a Kellner. It works very well in refractors over f/12.