CN FORUMS ARCHIVE Telescope Reviews: Post a picture of the scope you made

Someone was asking about these and I promised to post an image, so here it is.

The telescope on the left is a 10” f/6.7 I built in 1976. The telescope is an open-tube box structure built from ½” plywood and 2x2’s. The open-tube design was selected to reduce the weight and move the center of gravity towards the mirror to reduce the length of the tines. The mount is a polar disk where the north bearing is a 24” diameter disk built-up from three layers of ½” plywood. The fork is fabricated from 2x8’s while the base is built from ½” plywood and 2x6’s. The polar disk rides on two Teflon rollers (steel would also work, rubber wheels are too soft) while the south bearing is just the threads of the 1-1/2” pipe shaft screwed into a flange. The dec bearing are 1-1/2” PVC unions pressed into the tines. The dec shafts are 1-1/2” galvanized pipes attached to the OTA with flanges. The PVC unions were filed out to provide a smooth fit to the pipes, then greased. This mount was selected as an equatorial that could handle the weight of the OTA and not require any machined parts. The telescope gave excellent service for 30 years, but the OTA was recently retired so I could rebuild it out of much lighter materials.

The telescope on the right is a 16.5” f/6.7 ground, polished, and figured by hand in 1998. The OTA is an open box structure built from a mix of 3/16” hardwood veneered plywood, 2x2’s and 1x1’s. The struts are thin 2x2 angle aluminum re-enforced on the ends with short lengths of 2x2x1/8” angle aluminum. The mount is fairly standard except that all of the bearings rotate on pads made from polyester bunting. This displaces the load over a very high surface area providing a relatively smooth bearing despite the substantial weight. This OTA design was selected so that it would break-down into parts small enough to easily move in and out of my house or into the back of a small station wagon. Much to my surprise the OTA of the 16.5” has proven very rigid and has held collimation perfectly since it was first aligned about 8 years ago.

One feature both telescopes share is wheels built into their bases to make it easy to roll them on hard surfaces, though they’re tough to move on grass. The 10” isn’t too bad, but I have a set of plywood tracks I lay on the ground to move the 16.5”.

An interesting surprise is that although I built the 16.5” as a deepsky telescope my favorite object to view through this telescope is the Moon. The tremendous resolution and image scale makes the Moon truly look like a place full of rolling hills, mountains, and valleys. The other surprise was the beautiful colors I can see in faint stars. This is a fun instrument just to scan across the sky with. Since I started imaging I love to set my 16.5” up out in the yard while taking pictures with my LXD75 SN6. Once I know what I’m looking for with the imaging system I’ve found I can see much more visually through the big scope.

-John

Attachment

--------------------
-John

The best advice on imaging I've ever been given... don't forget to look!