Re: [ATM] Mirror cell

["Joe Morris" <joemorris@starband.net>]

Looks interesting, Cord. Tell me more about "press fitted delrin balls at
one end".  Is this an off the shelf item?

From: "Cord Scholz" <cord@astro-image.com>
Subject: Re: [ATM] Mirror cell

Good question. Arguably the best method is a Lasalle cell:
http://www.astrooptik.com/Projekte/Bilder/Pho_SpiegelZelle.gif
The disadantages are that it's difficult to make, heavy and expensive.
One solution that looks feasible - at least for medium sized mirrors - is a
perimeter ring with screws touching the mirror:
http://www.astropit.de/teleskop/spiebett.jpg
The guy made one mistake though, he used neoprene pads between the screws
and the mirror. This caused small changes in the position of the mirror when
he moved the scope. You probably won't notice it if you use the scope only
visually or with a small CCD but it's disastrous if you use a big chip.
I plan to use a similar solution for my 24", but I'll replace the nylon
screws with steel screws that have press fitted delrin balls at one end.

Cord Scholz
www.astro-image.com




-----Original Message-----
Joe Morris
Sent: Friday, November 11, 2005 1:43 PM
To: atm@atmlist.net
Subject: [ATM] Mirror cell

I'm planning an equatorial mounted Newtonian telescope with a 16" mirror.  I
understand that the mirror cell as used in a Dob with it's sling, won't
work. I understand the floatation system, PLOP, etc. but how is the mirror
held at it's edges?  Does anyone have suggestions for constructing the
mirror cell?


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