Criterion RV−6 "Dynascope" Telescope Restoration Project
You Can Own This Classic Telescope for Only $750 (my investment)

We will be moving back to Erie, PA, where overcast skies dominate, and the city lights kill views, so I am going to try to sell this before leaving. I'd keep it as a museum piece for display if I was going to have room, but we might be going into an apartment. The entire system has been stripped down and refinished, with original components retained for authenticity. Included are the telescope, mount, clock drive, finder scope, 9 mm and 18 mm eyepieces, 2x Barlow, dust covers. This is truly a unique opportunity. Please contact me via e-mail if you are interested in buying it. Local pick-up only, or I'll deliver for $50 within 100 miles of Greensboro, NC, with payment in advance. Thanks.

A few years back, I wrote about the Criterion RV−6 Dynascope, 6" Newtonian telescope I attempted to buy whilst serving in the USAF at Robins AFB, Georgia, in from 1978-82. Now, half a decade later, I finally found one at a reasonable price, where the owner was willing to pack and ship it. He did an excellent job with it, and even used a heavy cardboard SonoTube for protecting the optical tube. (This is the Criterion RV−8 Dynascope I had many moons ago, but unfortunately sold prior to another long distance move.)

BTW, here is an excellent article on the history of Criterion, "A Myopic View of the History of Criterion Mfg. Co.," by Richard Hill.

After performing a quick mirror alignment and using the original Criterion eyepieces, I looked at the moon and Saturn and was amazed at the quality of the image. A pert−near polar alignment was done and the clock drive was turned on. With Sirius centered in the eyepiece to begin with, it was still well within the field of view 20 minutes later.

The success of those two tests convinced me that undertaking a complete restoration would be worthwhile. The plan is to remove all the original crackle type black and silver paint, grind, sand, and/or sandblast the surfaces, then repaint. I was going to re-paint the original colors, but decided to paint the unfinished legs and tube rings a hammered black like the rest of the mount, and the optical tube is midnight blue.

Since completing the restoration, I did a more accurate collimation using a laser tool, and took the Criterion RV−6 Dynascope have had it out at night for testing. I have the two original 9 mm and 18 mm focal length eyepieces and the 2x Barlow lens. Beginning with the 18 mm, I found Jupiter and the four Galilean moons, and Saturn along with Titan. They were in very sharp focus. Changing to the 9 mm yielded amazingly good images - about as good as I remember seeing through my Celestron CPC−800 telescope (which I no longer own). I then put the 18 mm in the 2x Barlow lens and found the image was about as good as with the 9 mm. I bought a set of Plossls from Celestron, and they definitely yield better images than the originals from Criterion. To be fair, back in the 1970s and early 1980s, there was not a very large selection of good eyepieces at an affordable price.

I have a Plossl eyepiece set from Celestron that produces even better images than the original Criterion equipment.

The green felt material lining the main tube holder rings has been replaced with Teflon tape, which I already have. The felt does not allow the tube to rotate easily; the Teflon works much better.

The tube body (optical tube) is in pretty good condition both inside and out. I decided the original white shows marks too easily, so now it's midnight blue. Flat black was sprayed onto the interior surface.

Both the primary and secondary mirrors are in great condition, so I just gave them a careful cleaning. This Criterion RV−6 Dynascope will never be used for serious observing and/or photography, so re-surfacing will not be needed unless after use for a while it becomes apparent that treatment is justified.

Every bit of paint was removed from the metal parts using an air grinder with a stripper pad. I almost didn't want to put paint on them because they looked so nice. However, the hammered black Rust−Oleum paint on the metal components and the midnight blue on the optical tube looks amazing. The mirror polish on the steel axis axles look equally cool.

When reassembling the clock drive, the cracked cork gasket used for the clutch slip was replaced with a similarly sized toroid of plastic cut from a one-gallon milk jug. So far it works great.

These are a few photos of the process.

Criterion RV−6 Dynascope spotter scope and eyepiece holder.

Criterion RV−6 Dynascope equatorial mount & clock drive top view.

Criterion RV−6 Dynascope pier and tripod feet.

Criterion RV−6 Dynascope clock drive and setting circles.