Re: [APML] Off Topic: Achromat Config.

[Chris1011@aol.com]

In a message dated 7/17/2002 9:19:08 PM Central Daylight Time, celstar@frontiernet.net writes:


> . However, the surface which appears to be
> coated is the flat side of the flint glass, the last surface. I don't
> detect any coatings on any of the other surfaces. Does this make sense?
> Shouldn't the coated surface be the first surface the light would see?
> Will the lens set work if reversed?


The set will not work reversed. In the day that scope was made, they only coated one surface to save money. One surface was coated so they could say that it was a coated lens. In the past, I have coated a number of old 4" Unitron lenses because the inner surfaces were uncoated and was the cause of ghost images. The owners of these lenses thought that the images were superb, but almost all the lenses I tested ranged between 1/2 and 1/4 wave. The best Unitron scopes were the 60mm and 80mm sizes. In the larger sizes, the optical quality was iffy.

Unitron was a US sales organization that imported scopes and mounts made by various small companies in Japan. The quality of the optics varied depending on the subcontractors used at any given time. Ironically, the best large refractors were produced when Unitron used Jaegers lenses (made on Long Island) for a short period of time. The main Japanese supplier of tube assemblies and mounts was Nihon Seiko, and they went out of business about 15 years ago.

(more info than you really wanted to know)

Roland Christen