[ATM] RE: ATM Digest, Vol 10, Issue 17

["Cross, Timothy" <TCross@NRCan.gc.ca>]

Ken,
Would the coma of an off-axis Newt depend upon from where the off-axis
primary was cut on the parent mirror?  I.e. if you use a larger than
necessary primary (e.g. 16") to cut four 6" off-axis primaries and thus
avoid certain zones (e.g. the edge) of the parent primary, could you reduce
coma?  Obviously this wouldn't make full use of the parent primary mirror
though.  Very little coma has been reported by DGM off-axis Newt owners
however, so there must be some way to reduce coma in this scope design;
perhaps the off-axis primaries are refigured slightly after being cut from
the parent mirror?
Regards,
Tim Cross


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Message: 24
Date: Sun, 24 Oct 2004 17:20:30 -0700 (PDT)
From: Ken Hunter <atm_ken_hunter@yahoo.com>
Subject: Re: [ATM] Off-centered Mirrors?
To: DHA352@aol.com, atm@atmlist.net
Message-ID: <20041025002030.96344.qmail@web52703.mail.yahoo.com>
Content-Type: text/plain; charset=us-ascii

The coma is contributed by the photons that are coming
off-axis to the Parabola. In the case of a mirror like
you describe, you would get the same coma (but less
light) than you would from the original mirror.

Ken Hunter

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