Dear List,
I have decided to sell my one-of-a-kind fast, lightweight Newtonian
reflector OTA to help finance a larger project. I will try here first, for
a local sale, and if no takers will then list it on Astromart.
It is basically a standard newt, but designed to be as light and portable
as possible for a 14.5" aperture. It is an integral unit, and at 35lbs and
4' long, can be transported in any car without need of disassembly. Thus,
it stays permanently collimated and can be used immediately at remote
sites. Here are the details:
Primary Mirror:
14.5" precision annealed pyrex conical from Newport Glass. It is
2.5" thick in the cemter, tapering to 3/4" at the edge and weighs
20lbs. This style is structurally superior and does not require any
complex mount for support. It is bonded to a lightweight 3-arm mount by
RTV at the center 4". This is made from 1" square .063 wall 6061 aluminum
tubing and 1/8" plate welded together. It mounts to the .050 wall 6061 OTA
tube at the ends of the 3 arms, where the collimation bolts are
placed. This is so solid, it has not needed collimation for years, despite
travel to dark sky sites in the back seat.
The surface was ground and rouge polished and ronchi and star test figured
by Mike Spooner. The quality of this mirror is outstanding, like a
Zambuto, and provides tack sharp contrasty images even to 60x per
inch. I have compared the planetary views to a 6" Astrophysics refractor
and seen no difference. And this is an f/3.3!
The coating is the 96% enhanced by Spectrum done in June 2002. It is not
perfect but still in very good condition and does not need recoating.
OTA:
4' custom .050 wall 6061 aluminum lined with flock paper. Secondary is
3.14" 1/10 wave Newport Glass also coated by Spectrum with 96% enhanced in
6/2002. 4 vane steel spider with 6-point secondary adjustment. JMI DX-2
motofocuser.
Photos of the OTA, primary and ronchi are at:
http://pg.photos.yahoo.com/ph/mlinnolt/my_photos
Best offer over $3100 for the complete OTA for local bay area delivery
takes it!
Thanks for looking!
Mike
Received on Tue Apr 12 22:01:53 2005