Re: Masuyama's, what do we know about them?

From: Edward (reply_at_thegroup.thx)
Date: 07/31/04 

Date: Sat, 31 Jul 2004 20:01:47 GMT

"Mike Simmons" <mikes@mtwilson.nospam.edu> wrote in message

> We have an eyepiece at Mt. Wilson labeled "Masuyama" in a way that I've
> always taken to be the brand, not the design. In fact, I believe the
> design is a Kellner (labeled as such, IIRC). This is not a "normal"
> eyepiece, though -- it's focal length is 100mm and it's in a 4-inch
> barrel. We use it for visual observing at the f/16 Cassegrain focus of
> the 60" telescope. I can examine the eyepiece in more detail, if you
> like, when I'm back on the mountain in a few days.

Masuyama was indeed a brand. It came to be used in reference to all 3 group
/ 5 element eyepieces of that type. I know Masuyamas were available in
100mm, 80mm, 60mm, 45mm, etc. The 100mm was a unique design, three element,
2 group configuration with 46 degree Afov and 34mm of eyerelief.

Ed T.