Russ Jocoy's 9" F/4.8 Dob
Here are some images of Russ's first scope built around one of my
mirrors - a very nice 9" F/4.8 with a ~1/2"-thick plate glass
mirror. It was fun to figure, and is so incredibly lightweight
that Russ needed springs to counterweight the scope! The first
photo shows it in "high-contrast" mode, with shroud in place. The
second photo shows the simple truss structure and the upper cage.
It's a very compact scope, with a focal length of ~43", so it's a nice
sit-down scope for looking at whatever from the comfort of a chair.
Here's another view down the optical tube, showing the focuser
position (which has been moved, I believe, for more comfortable
viewing) and the attachment points for the truss tubes in the mirror
box.
Finally, a view of the scope from the back, showing cooling fan, a
possible counterweight, and the mirror cell structure.
All in all, Russ really enjoys the views from this scope. He
says: "The veiws from this "little" DOB are fantastic, It needs
to be collamated correctly.... Once this is done, the mirror will
produce images exceeding my 8" SCT Meade on a good night. My only wish
is for a tracking platform to really tweeck to the limit. This
scope wiegh's 47 lbs total... and yes the mirror is about 48 ozs... I
obviously over-built my first scope, but it is a trooper for the road,
sky, and sharp images on clear skies.."
What we are discovering is that thin plate glass
mirrors can provide excellent images. What I am discovering is
that such mirrors can be made with care, skill, and a bit of
practice. Maybe one of these days I will finally meet Russ in
person and get to see the images my mirrors (9" and 13.1") are
providing in his home state of Florida.