Oregon Star Party 2008
Mel Bartels, August 2008
images by Greg Babcock,
Howard Banich, Mark Thorson
Each year we hold a telescope walkabout at the Oregon Star
Telescope builders share their experiences making telescopes.
People walkabout the telescopes to enjoy the telescope making
experiences and to garner ideas for their own telescopes.
Here's a typical scene: Q&A on one of the walkabout telescopes.
This year's themes are string scopes, travel scopes and
start with Chuck Dethloff's 16 inch f/4 (Swayze mirror). This
scope features a lightweight double ring upper cage; eyepiece shade and
a low height box. The batteries are attached below the mirror
mount in an unique manner, which results in a downward shift of the
center of gravity by 2.5 inches. Chuck designs his scopes for
superb responsiveness when hand pushing it for finding and high power
tracking. The upper cage uses ABS plastic, an improvement
the popular Kydex, which can deform in the hot sun. The
weight of the scope is 100 pounds. Finish is Boat Koat UV
varnish, 5 coats sprayed on and sanded.
we stepped over to Steve Swayze's 18 inch f/3.5. It's a
reclamation project with veneered tube end rings, a Swayze trademark.
Its remarkable that one has to stoop to look through the
when the scope is pointed vertically. This is definitely
no-ladder territory. The views through the eyepiece at night
stunning, particularly with the 8mm Ethos and the bino viewer.
is Dave Nemo's 20 inch string scope. Dave found the mirror at
garage sale... get this... for $100. Dave first built an 8
prototype to understand the principles and work through iteration #1.
Dave built from wood because he knows wood; the scope was
finished in eight weeks in time for OSP. He used common
that were easily available. Dave was inspired by the other
motored on over to Greg Babcock's 12 inch f/5 traveller, inspired by
Greg's earlier 10 inch traveler and Albert Highne's telescope design.
The lid becomes the ground board. The truss poles
into interior connectors. The scope started as a commercial
inch dob, purchased used. Greg used Baltic birch throughout,
the total weight of the scope pegged at 40 pounds.
inch traveller is the scope on the left of the image immediately below.
Powell's 12 inch f/6 string scope, named "Beautiful Blue", is an all
aluminum scope. All poles are interchangeable. Dave
ball bearings for very smooth motion, and uses the 3 vane spider design
that Greg Babcock first used on his 18 inch scope back in the late
The aluminum is water jet cut, including the 'stars'. Dave's
is the scope on the right of the image immediately below.
It's an interesting comparison of purpose and technique for the
identical aperture of 12 inches.
Martin's 16 inch f/4.5 'Pegasus' dob saw first light the night before.
(This is a time honored tradition at the Oregon Star Party:
of us have labored long days and nights immediately preceeding the star
party, with first light the first night of the star party).
mirror box fits under his bed (away from cats and kids!).
being a woodworker, the mirror box is all wood including the mirror
mount. The 6 pt cell design is by Albert Highne, with the
being glued to the cell. The lightweight upper end baffle is
from 1/16 inch thick wood. This is Dave's third scope and
walkabout ended with Ross Robert's 3-mirror 16 inch f/5.7 folded
Dobsonian. Ross, one of the excellent Portland, Oregon,
makers, designed this scope to be optically folded, resulting in a
reduced height of 3 feet. Like others, first light was last
night! Ross uses a SiderealTechnology drive, with full goto
tracking. Ross designed a 27 pt cell for the 1.6
Swayze refigured mirror. The secondary is 5.7 inch
made by Discovery Optics, and relatively expensive. At full
height, Ross sits down to look through the eyepiece. In fact,
eyepiece has very little movement to it as the scope is moved from
horizontal to vertical. Like Dethloff and others,
Ross uses a
full eyeshroud to improve viewing of extremely dim objects.
reports that optical alignment can be tricky.
concludes the walkabout. Here's another interesting
from the 2008 the Oregon Star Party. This is a 16 inch that
features a single arm fork mount, designed and manufactured by Greg
Babcock back in the 1970's. The mounting was pulled from long
term storage at the local planetarium by Tom Conlin. Tom's
cell is beautifully machined. It too is a string scope.
Sky and Telescope's report of the 08 OSP http://www.skyandtelescope.com/news/27768494.html
Pics AND video of the walkabout http://thebrownings.name/med/