Finder 'scope extension.

[Grierson]

I have a SW right angle finder 'scope. I want to remove the right angle and extend the tube 40mm to turn the 'scope into a finder/guider using one of Modern Astronomy's adapters to fit my Mini ZWO ASI120mm camera. Trouble is I can't find a suitable 40mm extension tube. The outside diameter of the tube is 53mm the inside is 50mm however I have no knowledge of how this diameter of tube is correctly described. Can anyone help or perhaps provide a link to a suitable item? Many thanks - John 

(ps I would swop someone the right angle finder for a straight through one if anybody near York needs a right angle one.  🙂)

[Dr_Ju_ju]

I hate to say it, but that sounds like a classic option for a 3D printed part, I've just done something similar for a stage 1 conversion of a PST, to allow it to mount into a standard 2" eyepiece fitting.

[johninderby]

I have one of the these finder to T2 adapters in the Assorted Bits listing in the sales section. Just use a standard T2 extension tube or a T2 to 1.25” adapter with it.

https://www.firstlightoptics.com/adapters/astro-essentials-sky-watcher-9x50-finder-to-t-adapter.html

Edited May 3, 2020 by johninderby

[Grierson]

38 minutes ago, Dr_Ju_ju said:

I hate to say it, but that sounds like a classic option for a 3D printed part, I've just done something similar for a stage 1 conversion of a PST, to allow it to mount into a standard 2" eyepiece fitting.

Thank Dr.  but I have so far resisted the purchase of a 3D printer!!

38 minutes ago, johninderby said:

I have one of the these finder to T2 adapters in the Assorted Bits listing in the sales section. Just use a standard T2 extension tube or a T2 to 1.25” adapter with it.

https://www.firstlightoptics.com/adapters/astro-essentials-sky-watcher-9x50-finder-to-t-adapter.html

Thank John. Trouble is the adapter is 50mm. 

[johninderby]

1 minute ago, Grierson said:

 

Thank John. Trouble is the adapter is 50mm. 

??? But the adapter fits a Skywatcher 9x50 right angle finder  which has an M51 thread.

[Grierson]

Sorry John for the confused reply. I don’t want to reduce the diameter of the tube which appears to be the use of the item link you kindly supplied.

[TerryMcK]

The internal thread of Skywatcher Finder scopes (and many clones) is M51 x 0.75. You may be better off buying a straight SW guide scope and Astro Essentials Sky-Watcher 9x50 Finder to C Adapter from FLO (£39 and £29 respectively) rather than trying to find something which probably doesn’t exist.

Edited May 3, 2020 by TerryMcK

[Grierson]

On 03/05/2020 at 19:25, TerryMcK said:

The internal thread of Skywatcher Finder scopes (and many clones) is M51 x 0.75. You may be better off buying a straight SW guide scope and Astro Essentials Sky-Watcher 9x50 Finder to C Adapter from FLO (£39 and £29 respectively) rather than trying to find something which probably doesn’t exist.

Yep, you're probably right 🙂.