Re: ATM Ultra-Light Dobs mounts

["Chris Westland" <westland@uxmail.ust.hk>]

 BTW  I had a question about Starlight Instruments, the company that makes
the "Feathertouch" focuser ... does anyone know whether they are still in
business.  I have tried calling their number in Schaumburg IL and found it
disconnected

Chris Westland

-----Original Message-----
From: Chris Westland <westland@uxmail.ust.hk>
To: Carl Woebcke <carlw@telis.org>; atm@shore.net <atm@shore.net>
Date: Tuesday, September 09, 1997 8:50 AM
Subject: Re: ATM Ultra-Light Dobs mounts



> Carl:
>
>I was going to send this off to Mel, but let me throw it up to the  list.
>I think that the critical factor in ultralight Dobs is getting the weight
>down on the upper tube assembly.  Mel has done a beautiful job of this with
>his appleply ring and rear baffle.   Several ideas to take this a step
>further
>
>(1) graphite composite ring.  Make it "L" shaped for stiffness with holes
to
>lighten ... messy, but doable
>
>(2) alternatively, use a bent aluminium tube 1" to 1.5" ... tougher to do
>than it looks
>
>(3) rather than a flat circular baffle, use louvers which overlap, and
which
>might be painted flat black.  This would reflect light out at a harmless
>angle, and would be less likely to be buffeted by the wind.
>
>(4) I like the idea of the "L" brackets to prevent twisting of the
secondary
>mount ... but why not a mount that is three dowels silicone adhered to the
>back of the secondary mirror.  Wind would just whip through ... or on a
>Novak style holder, drill lots of holes in the holder
>
>
>As Mel noted, without the tube or shroud between primary and secondary,
>baffling becomes a simpler affair ... only needed right around the mirrors.
>And you have much better overall control of stray light ... in an ordinary
>tube, most of the stray light is reflected off of the tube ... in the open
>Dobs, it just escapes out the sides.
>
>One problem with this openness is the observer's body heat ... perhaps a
wet
>suit is the answer ;-0
>
>Chris Westland
>Hong Kong (now part of China, though you wouldn't know it)
>
>
>-----Original Message-----
>From: Carl Woebcke <carlw@telis.org>
>To: atm@shore.net <atm@shore.net>
>Date: Tuesday, September 09, 1997 6:56 AM
>Subject: ATM Ultra-Light Dobs mounts
>
>
>
>>Hello out there,
>>
>>While I'm waiting for Mel's Ultra-Light web page to come back up, and
>>for Bruce Sayre to return (If you haven't seen Mel's and Bruce's
>>Ultra-Lights yet, I STRONGLY recommend them.  They're beauties!), I was
>>wondering if anyone else had any plans or experience for an ultra-light
>>mount for an 18" mirror (f4.5)?   Thanks.
>>
>>
>>Carl Woebcke
>>carlw@telis.org
>>
>