RE: [ATM] New 8" Travel Dobson

["Peter" <peter@kitgear.com>]

Hi Stathis, Petra & Gernot,

Wonderful web page and congratulations on your new travel scope!

You've done a wonderful job at explaining the challenges of building a small
high performance travel scope. I could not have expressed it any better.

I went through the same decision regarding my selection of focal length. I
went for 1080mm (f/5.3). I simply sat in my observing chair and had someone
measure my eyepiece height. Objects near the zenith are in the perfect
viewing position but objects near the horizon are uncomfortable because the
eyepiece is too low.

Please send me details about your altitude break. My design uses a 2"
focuser and changing those big Naglers causes the scope to move. The smaller
eyepieces are OK. I'm very interested how you solved this problem. Also how
long does it take for you to setup and collimate the scope?

Your article talks about reducing upper cage weight. You are exactly correct
on this as I had the same decisions to make. I chose to use 3/8" Baltic
Birch plywood in order to save weight. I also made the spider the same
thickness but it is made of 0.025" steel. In the end my secondary ring is
stiff and provides enough support for the secondary with no perceivable
collimation shift throughout the vertical travel. If you make any
improvements to your scope then please forward these to this group.

Congratulations once again on a fine job!


Peter

-----Original Message-----
From: atm-bounces@atmlist.net [mailto:atm-bounces@atmlist.net]On Behalf
Of Stathis Kafalis
Sent: Wednesday, September 15, 2004 1:20 PM
To: atm
Cc: stenzg@in.tum.de
Subject: [ATM] New 8" Travel Dobson


Hello list members,

may I introduce the new 8" f/6.25 travel Dob that Petra and Gernot build
during our Munich mirror making group:
http://www4.in.tum.de/%7estenzg/reisedobs.html

- selfmade mirror (of course) - a very fine piece of glass
- one ring upper part with excentrical spider
- foldable 6 trusses
- compact transport - all parts fit into each other

First light was on La Palma / Canary Islands

Greetings

Stathis Kafalis
www.stathis-firstlight.de

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