built 8" f/12 for sale
8" f/12 ultra light lunar planetary OTA
Actual focal length
is 93". During mirror fab, if left as a sphere there would
be ~1/4 correction error. So this mirror was then slightly aspherized
to null far better than that limit. The primary blank is a lightweight
Celestron SCT cast Pyrex blank. This uses center attachment to
a light weight adjusting rear cell. Lunar planetary performance
OTA is in 2 sections
both 44 1/2" long. Upper is 3 1/2 pounds and lower is 11
All fastners are SS
and hex wrench type. The focuser is modified for closest location,
with shortened chrome ocular tube. It has very smooth movement.
8 each very light weight
lathe turned rings at ends of truss assemblies and tube sections.
All aluminum is black anodized. Truss tubes are epoxy wound G10
fiberglass. Light and rigid.
diagonal mirror is
1 1/4" minor axis (3% area)
Total weight with rings
is 17 1/2 pounds. Aluminum tubes are white epoxy painted and the
main center tube rotates smoothly in the felt clamp rings.
Focuser is shortened
and is at max in travel, and still not in the beam.
Heavy tube rings are
machined cast aluminum @ 6 pounds w/ 8x50 illuminated finder
to for sale
Contact Jim Riffle, 928-685-2261