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Re: [APML] Astrograph?????

To: astro-photo@seds.org
Subject: Re: [APML] Astrograph?????
From: Chris1011@aol.com
Date: Tue, 13 Nov 2001 12:01:04 EST
Reply-To: astro-photo@seds.org
Sender: owner-astro-photo@seds.org

In a message dated 11/12/2001 11:38:41 PM Pacific Standard Time, gamble@peoplepc.com writes:

Does anyone know of websites where explanations
and/or illustrations of what qualifies a scope to be an astrograph as well
as design techniques might be available

An astrograph would be any scope that produces a flat photographic field over a specific format. It could be 35mm or as large as 8x10". Usually, once you go over a 6x7cm format, refractive systems are the best choice because they can be designed to cover large fields without noticeable vignetting. I have a 3 element Fluorite astrograph designed by Mike Simmons that covers a 14 degree field with a 6" aperture and a 48" focal length.

Roland Christen

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