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Tim Pimentel bought this 6 inch F15 refractor optical tube assembly from
D&G Optical.
Tim says "I do not have the patience to build my telescopes or their mounts, though I
will make minor modifications in order to satisfy my needs. Oddly, I seem able to plan,
save for, and wait for delivery of commercially built equipment. To this end I ordered
a 6 inch F15 Optical Tube Assembly from D&G Optical to use on the Losmandy G-11
mount which came with my Celestron CG-11."
The tube assembly comes complete from D&G, including lens and eyepiece adaptor
caps, with the exception of a means to attach it on a mount. The tube is 7 inch O.D.
aluminum, painted gloss white on the outside and flat black on the inside. It has
three internal baffles to control off-axis light rays.
The air-spaced achromat doublet lens is mounted in an aluminum push-pull adjustable
lens cell. The dewcap is 10 inches long, about 1 inch larger in diameter than the
lens cell, and about 1-7/8 inches larger than the clear aperture of the lens. It is
secured with a thumb screw that has a plastic snubber to avoid marring the lens cell
when tightened.
The rack and pinion focuser has a 2-3/4 inch inside diameter, and 5-5/8 inches of
travel when it is on the rack. When racking in, it can run past the point where it
runs off the end of the rack and can no longer be driven by the pinion. This is really
no problem since it can be put back on the track easily and is way inside useful focus
when it occurs. The focuser has an adjustable thumbscrew that can be used to increase
focuser friction or as a lock. It is ready for 2 inch eyepieces and comes with a 1-1/4
inch eyepiece adaptor.
The 8x50 finder scope came from Orion Telescope Center
and mounts on a quick release dovetail mount.
The G-11 Losmandy mount from Hollywood Machining is extremely capable and I use it with
Celestron C-8 and C-11 Schmidt-Cassegrain tube
assemblies and the D&G refractor. I have added Celestron's Astro Master Digital
Setting Circles with mounting hardware from
Jim's Mobile Inc.
The mount came with 48 inch fixed length legs that I use with the C-8 and C-11, but I
had to get 60 inch legs from Hollywood Machining to get the mount high enough for the
7 foot plus long refractor tube assembly.
To mount the tube assembly on the equatorial head I purchased a 17 inch dovetail plate
from Hollywood Machining. On this I mounted 7 inch tube mounting rings from D&G.
The refractor nestles snugly in the felt lined tube rings.
Without a doubt the value is built into D&G Optical instruments. I am impressed
and very pleased with the performance of my classic F ratio
refractor. - Tim Pimintel
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