Re: [ATM] Supplies I need

[Michael Lindner <mikell@optonline.net>]

On Saturday 19 June 2004 06:32 pm, David Williams wrote:
> Does anyone know of a place on the internet for a new or used spider for a
> 24" outer diameter tube (sonotube) and the price for an elliptical diagonal
> (new or used on the internet) for a 20" mirror.

There are a bunch of links to making or acquiring ATM supplies at 
http://www.starastronomy.org/TelescopeMaking/Links/ The Amateur Telescope 
Maker's Resource List is one of the best links there, but it doesn't seem to 
be working. Does anyone know of a mirror (I recall there were a couple)?

I have bought several spiders from Gary Wolanski, and been very pleased with 
them http://www3.bc.sympatico.ca/gwolanski/SPIDERS.HTM Protostar is another 
good supplier http://www.fpi-protostar.com/diagmnt.htm These are not the only 
two, but the first two that happened to pop into my head.

As for secondary mirrors, what size? You didn't mention focal length, but 
since your sonotube is 8' long, I'm assuming this is an f/4? If so, you could 
get by with a 3.5" for visual use, up to a 4.5". Protostar sells diagonals 
http://www.fpi-protostar.com/pyrex.htm as well as Antares 
http://www.antaresoptics.com/SecEM.html and a bunch of other places. Again, 
these are just the first two that popped into my head.

> ...a program to show you how to
> lay out your mirror and diagonal and spider.

Dale Keller's Newt program 
http://home.att.net/~dale.keller/atm/newtonians/newtsoft/newtsoft.htm is what 
you're looking for. Also Mel Bartels' diagonal calculator 
http://members.efn.org/~mbartels/tm/diagonal.htm can help you choose a 
secondary size...

-- 
Michael Lindner
http://www.starastronomy.org *** http://home.att.net/~mikel
http://www.atmsite.org *** http://www.atmlist.net

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