Borg helical focuser to stop refractor image shift

[dweller25]

My TSA102 despite numerous attempts to tune the focuser annoyingly still has a little image shift when trying to get fine focus on the planets at high magnifications and is quite stiff ( the best option for the least image shift !)

Putting a Feathertouch on would sort it out but they are very expensive so I am thinking about putting this Borg helical focuser on the back of the scope for fine focus.......

https://www.firstlightoptics.com/borg-helical/borg-helical-focuser-s-7315.html

I am wondering if anyone else has tried this and if so how did it work out ??

[timwetherell]

I'd be interested to know about this too. I was too cheap to buy a real one so cannibalised one from an old 200mm telephoto lens. It works but there is some slop in it. If I could be sure that the Borg was slop free, I'd put my hand in my pocket for one. 

[johninderby]

I tried thiat one and found it was only usable when mounted in a diagonal as it was simply not strong enough to handle side loads without flexing.

I used the bigger 7857 version on a PST conversion a few years ago and it did work well but of course more ££££

[Moonshane]

Could you use a Baader t thread helical?

https://www.firstlightoptics.com/adapters/baader-t-thread-to-125-helical-focuser.html

[dweller25]

1 hour ago, johninderby said:

I tried thiat one and found it was only usable when mounted in a diagonal as it was simply not strong enough to handle side loads without flexing.

I used the bigger 7857 version on a PST conversion a few years ago and it did work well but of course more ££££

Thanks for the excellent feedback John.

[dweller25]

35 minutes ago, Moonshane said:

Could you use a Baader t thread helical?

https://www.firstlightoptics.com/adapters/baader-t-thread-to-125-helical-focuser.html

Actually - YES - I have a Baader prism that will accept this  - thanks for the idea ?

[dweller25]

Update - bought the Baader helical focuser and it worked perfectly ?

[Merlin66]

I use the Borg helical on my Spectra-L200, PST mods and the spectroheliograph- no issues no drama.