Re: New AP scope and more

From: Chris1011 (chris1011_at_aol.com)
Date: 10/28/04 

Date: 28 Oct 2004 22:00:03 GMT

>>Maybe one day we will have some type of glass to make a color free achro
doublet.>>

It's called Fluorite and when coupled to a Schott N-KzFs2, it will produce what
you want - pretty well color free doublet.

Fluorite costs about $1000 per kg in raw form. A 9" blank would weigh about
4.5kg.
The Schott mating element will cost about $1500 to $2000 in raw form.

Then comes grinding, polishing, figuring, anti-reflection coating (at ~$400 per
surface), mounting in cell, making the tube assembly with focuser, dewcap,
baffles, etc. Some profit for the telescope maker, some money for national,
state and local taxes, a bit of overhead, etc etc etc. Where do you think this
will come in at, comfortably?

Roland Christen

Relevant Pages

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  • Re: spotting scope question-specific
    ... Takahashi has used fluorite, the original ... If you want to make an apo using three glasses, ... Any three glasses will not make an APO. ... (ED glass can make a very flat parabola, so that even though the quality of the chromatic aberration is that of a doublet, the degree of color can rival a apo. ...
    (rec.birds)