I bought this lens used (very used!) in San Antonio. It is a
fantastic lens for astrophotography. This lens weighs about
6 pounds. It mounts directory to a tripod socket. The Losmandy
DCM2 camera mount is a very heavy-duty piece of equipment, but
is hard to tighten to the point where a large, heavy lens does
not shift. Thus, a brace was necessary.
The brace is made from "cutting board plastic", available in several
thicknesses and colors at most plastic supply companies. I used a
tablesaw to cut out the pieces and a router with a 1/4 inch spiral upcut
bit to make the adjustment slots. I drilled and tapped the adjustment
holes to accept a 1/4-20 nylon bolt.
Cutting the dovetail socket into the bottom of the brace was by far
the hardest part. I did it with the tablesaw, the blade raised about
3/16 inch above the table surface. Moving the block of plastic back
and forth slowly removed the material, leaving a faily flat surface
to ride on top of the dovetail. Next, I tilted the tablesaw blade
to match the angle of the Losmandy dovetail plate and cut the two
dovetail corners. A 1 inch deep slot with a tapped hole and bolt
allows the base to tightened to the dovetail, securing the brace
I made one change from my original plan: instead of an angle cut to
cradle the lens, I cut a curve with the router and circle jig to
match the lens's barrel. A strip of Velcro (the fuzzy side) provides
a soft "landing area" for the lens. A small bungee cord wraps around
the len and is secured to each side of the brace to keep the lens
secure and immobile as the the mount tracks.
I have been using the brace for years now, and have had no problems
at all with it. Slides from 60 minute exposures show no indication of
the lens shifting.