Thread on the back of a 1980 dynamax 8 SCT

[5ash]

I recently acquired an 8” criterion dynamax SCT and would like to know the thread type on the rear of the telescope so I can get an adapter to attach a
celestron or Meade 1.25” visual back. The visual back I have is showing it’s age.
Optically it’s fairly good and I’ve heard all the problems associated with this scope.
Grateful for any advice , regards philip

[Merlin66]

I had assumed it was a "standard" SCT thread - 2" x 40tpi, the same as the Meade and Celestron.....

[5ash]

Hi, Ken , wish it were so, appears to be smaller diameter.
Regards philip

[5ash]

Hi Ken, I thought I had a retaining ring for a celestron visual back in my bits and pieces and tried it and it didn’t fit . So maybe my bit is not what I thought.
Thanks for your help regards philip

[astro744]

Contact Astroptx as they may be able to sell you an adaptor.

See http://www.astroptx.com/contactus.html and

See http://www.astroptx.com/bauschlombcriterion.html

[RyanJones]

I heard that some of these early SCTs had an odd thread the same as the later 4se which I happen to have an adaptor for. Mine is a t-adaptor but if the locking ring will slide over your visual back you could make it work maybe. Happy for you to try it for the price of postage ?

[doppler]

Hi, maybe one of these will work. The diameter on the back of older skywatcher mack cass scopes is smaller than 2" (about 1.8").

https://agenaastro.com/blue-fireball-sct-thread-adapter-maksutov-cassegrain-telescope.html
Rick

[5ash]

Thanks for all the info , great help regards philip:thumbsup: