RV−6 Dynascope Advertisement
Criterion RV-6 Dynascope, 6", f8 Newtonian Telescope before restoration.
RV−6 Dynascope tripod mount components before restoration.
Looking through the RV−6 Dynascope eyepiece holder toward the
Looking down the tube toward the RV−6 Dynascope primary mirror.
Rear view of the Criterion RV−6 Dynascope primary mirror and mount.
RV−6 Dynascope clock drive.
RV−6 Dynascope main worm gear before restoration.
RV−6 Dynascope clock drive motor.
Criterion RV−6 Dynascope after restoration.
Note: We are 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. Includes 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
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 a 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.
Since completing the
restoration, I did a more accurate collimation and took the Criterion RV−6
Dynascope out at night for a test drive. 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
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.
RV−6 Dynascope tripod mount components after restoration.
Painted components drying in the sun. Three full coats of Rust−Oleum "hammered metal" black spray was applied after
a thin coating of acid etch aluminum primer.
Optical tube mounting rings and declination axis
Paint stripped from aluminum clock drive housing and pier alt-az
Restored clock drive assembly.
Criterion RV−6 Dynascope mirror alignment view.
Criterion RV−6 Dynascope diagonal mirror components.
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
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
Criterion RV−6 Dynascope pier and tripod feet.
Criterion RV−6 Dynascope clock drive and setting circles.
"Pert-near" is a phrase used the classic American television show "The Beverly Hillbillies." It
is a contraction of "pretty near" and is often used by the character Jed Clampett,
played by Buddy Ebsen.
Jed Clampett, a kind-hearted hillbilly from the Ozarks, strikes it rich when
oil is discovered on his land. As a result, he moves his family, including his daughter
Elly May, his mother-in-law Granny, and his nephew Jethro, to the upscale neighborhood
of Beverly Hills. The show follows their humorous misadventures as they try to navigate
the world of wealth and luxury while maintaining their down-to-earth country ways.
"The Beverly Hillbillies" aired from 1962 to 1971 and became one of the most
popular sitcoms of its time. The characters and their catchphrases, such as "Pert-near,"
have become iconic in American television history.
Posted July 17, 2023