Criterion DynaScope 6"

[deg13122]

Greetings,
I have a 50+ year old Criterion 6" DynaScope.
It still works just fine. I rebuilt the clock drive and the clutch a couple years ago.
The sharpness of the views is better than my 10" Apertura dob! Same mirror, original coating.
Problem is - the eyepiece holder is a brass tube "about" 1-1/4" ID with no set screw .
My current eyepieces flop around in the holder and I want them sorta snug, but not so tight I can't remove and replace without knocking the scope off target.

DynaScope6.JPG (24.71 KiB) Viewed 2753 times

What to do? What to do?
Dennis

[helicon]

Can you replace the focuser? This is a simple way to solve the problem. Also, congrats on holding onto a classic scope for 50 years. I remember seeing the Dynascopes in Astronomy Magazine and always wished I could afford one.

[smeyer8015]

O have one also. A bit disassembled though.

It says Edmund Scientific on it, but it looks identical.

[smeyer8015]

Here is the focuser.

[helicon]

Dennis, another idea is to look at ebay. I found an old 1 1/4" Dynascope focuser for sale for $11 (since sold) so I guess it depends if you want to replace the focuser with another Criterion one or get something new as a replacement...

[John Baars]

It is clear to me that the focuser holds the eyepieces on clamping. Due to use or improper use, space has been created there. The two halves that hold the eyepiece are bent outwards.
With some care, those halves can be bent back in, so that they hold the eyepieces again. They won't break off on the first attempt to bend them in.

If you are afraid of that, you can heat them first, with a lighter for example. The following applies to everything: do it with policy.

I would try this before buying a new one.

[deg13122]

Can you replace the focuser? This is a simple way to solve the problem. Also, congrats on holding onto a classic scope for 50 years. I remember seeing the Dynascopes in Astronomy Magazine and always wished I could afford one.

Yes, I can replace the focuser, but I'm trying to keep it as "original" as possible.
Since my last post I found that there is an extension sleeve lodged inside the focuser tube!
Getting this out (been stuck for years) gives me the correct size to hold EP's.
It is a tight slip fit, so it can be pushed back and forth with very little effort -- but it's there, and it works.
Thanks for your comment.
Dennis

[deg13122]

It is clear to me that the focuser holds the eyepieces on clamping. Due to use or improper use, space has been created there. The two halves that hold the eyepiece are bent outwards.
With some care, those halves can be bent back in, so that they hold the eyepieces again. They won't break off on the first attempt to bend them in.

If you are afraid of that, you can heat them first, with a lighter for example. The following applies to everything: do it with policy.

I would try this before buying a new one.

Thanks John - I got it figured out. There was/is an extension sleeve that was pushed all the way and more into the outer tube. Pulling that up and out about an inch solved my problem.
Dennis

[Makuser]

Hi Dennis. I am glad that you found the extension sleeve, and solved your focusing problem. I remember back in the day when I was young, everybody wanted a Criterion RV6 (or RV8) Newtonian or a Unitron refractor. Thanks for your post Dennis, which takes many of us back down memory, and I hope that you continue to enjoy this vintage telescope.

[deg13122]

Hi Dennis. I am glad that you found the extension sleeve, and solved your focusing problem. I remember back in the day when I was young, everybody wanted a Criterion RV6 (or RV8) Newtonian or a Unitron refractor. Thanks for your post Dennis, which takes many of us back down memory, and I hope that you continue to enjoy this vintage telescope.

Thanks.
I first saw the DynaScope ads in Boys Life when I was in scouting in the late '50's.
I wanted one so bad but my dad, who was also interested, told me that he could only afford up to $50 at that time.
I guess in today's dollars the $194 would be around $2000!
I was given this scope about 3 years ago by a fellow member of the Fort Bend Astronomy Club here in the Houston TX area.
It was a "first one who calls me gets it" deal, and I called back within 5 minutes!
I'm so glad to have the "telescope of my dreams."
Don't use it much as I have 8" and 10" dobs, but it stands at a place of honor in my man-cave.
Stay safe.
Dennis

[XCalRocketMan]

The RV-6 was, and is, a great scope. I had one for years when I first started out in Astronomy - my dad decided to pick one up at the factory in Hartford on our way back from a summer vacation on Cape Cod. I even attempted astrophotography with it using 35mm and Tri-X film. Set up my own darkroom in the lower level bathroom of my parent's house. Boy, was that fun - both the AP and the film developing Sold the RV-6 to a friend in the mid 80's. Not sure if he still has it.

I was going to ask if you had the thin sleeve, but I see you got it straightened out.

[mikemarotta]

... I have a 50+ year old Criterion 6" DynaScope.
It still works just fine. I rebuilt the clock drive and the clutch a couple years ago.
[...]
I first saw the DynaScope ads in Boys Life when I was in scouting in the late '50's.
I wanted one so bad but my dad, who was also interested, told me that he could only afford up to $50 at that time.

That was my limit, so I got the Criterion 4-inch reflector (mechanical mount) for $50. That was 1961. It served me well enough from ages 11 to 15. Then other interests took hold at the same time that we moved to a different neighborhood. I went many years without a telescope of my own, though I did use a couple of college observatories. My wife and daughter bought me a telescope in 2014 and I picked the Celestron 130 EQ as being closest to the Criterion 4-inch. It was not. The Criterion was much better. They don't make 'em like they used to.

(One thing, though, I will say about modern times. We have affordable instruments that would have been the envy of professionals of 50 or 100 years ago. I mean, granted, that the low-end suffers from cheapness in trade-offs for things like hardware, mount, screws, nuts, and bolts, but the optics are unbeatable for the price -- and they are computer controlled. Imagine if you could take one back in time to Maria Mitchell, Annie Jump Cannon, or Antonia Maury. The crime and the glory is that these things can sit unused in closets, attics, and basements.)

[Jones]

I bought a Criterion mirror off ebay and the focal length is 50", is yours the same?

[Jones]

I bought a Criterion mirror off ebay and the focal length is 50", is yours the same?

[deg13122]

Jones. Sounds about right. My scope with original unrecoated mirror gives me sharper views than my more modern dobs. They made them well back then.