I've been quiet in the background for the past couple of months. Just getting/ making the time to get the gear unpacked.
First cab off the rank is the TS102 PST Mod. This 102mm f11 scope is made by Hunming (United Optics), China and sold in the UK as the LYRA. It's a great scope, and perfect for the PST mod (as others have already found)
I machined up an adaptor which just replaces the original Crayford focuser. (There's a dovetail connection on the rear of the OTA - just needs 3 x M4 nylon screws to lock it in place)The 2" PST nosepiece is held securely by 3 x M6 nylon screws. No cutting of the OTA and the adaptor can quickly be removed and replaced with the original focuser for white light observing.
I've also machined up a cell to take the SM60 etalon to give double stacking....
Good to be getting back into it.
Peter,
99% of the spacers etc are T threaded with the helical focuser there no movement. The nosepiece adaptor was the only compromise. I made the adaptor body full length (with three screws) to give maximum support.
Seems to work OK.
When I get back into imaging we'll see for sure.
These added images show the quick change over to the Baader wedge for white light observing.
10sec job....Much better than cutting the OTA!!
That is a great solution and keeps the scope intact. Looks pretty solid too.
BTW, I have a spare 'Mark Townley' ring, if you need one, let me know and I'll chuck it in the post.
Peter,
Thanks for the offer...I have one but not fitted it yet....
To answer a question I got - How can you focus the scope without the Crayford?
The PST etalon mod doesn't require an "up front focuser". The position, after final adjustment, is FIXED at -200mm inside the prime focus. It never moves again.
The final focus is obtained using a Borg helical focuser between the etalon and the BF diagonal. You can easily focus for visual or any camera.
(I have a detailed write-up available for the PST mods...PM an email address for a copy)
Ken,
It's looking really good, I printed a "plug" on my 3d printer to accept the 2 inch nose piece, it works a treat. Thanks for all your work on the modification front. I'm never looking back.
Trent,
I'm glad things worked out!
The PST mod is one of the most exciting things you can do with a PST!
We've also recently managed to mod a Lunt 60!
Majic happens!
Hi Ken. I've just sent an email re: the borg helical focuser. Has this been added to your write up on the mods you sent me earlier in the year? Thanks for all your help so far. Have a great and safe New Year. Cam.
Cam,
The PST write-up hasn't been updated. There's a revison in progress.
The Borg focuser is just one of the many possible solutions, but does seem to work very well.
Sweet work Merlin have being following you, nearly cyber stalking lol on many other forums with your work on the PST's. Preying to get ours done (Stage 1 mod) soon with your tutorial thanks