10 replies to this topic

[Mike Conley]

I have a single speed moonlight crayford on my dob and was thinking on adding this accessory. I read a review here on CN recently ( EP review ) , that mentioned a company that was producing a nice unit for 30-40 dollars ( not orion ). Can anyone point me in the right direction. Opinions welcomed.

Thanks Mike

[mclewis1]

Hutech sells a Borg helical focuser that has a variety of mounting options (threads and 2" barrel).

[Rat8bug]

I second the Borg Helical.....

http://www.barrie-ta...estar_life.html

Ciao....BC

[jcjr]

I've been looking at the borg helical focusers, and if 1.25" is OK, and you have a good bit of extra in-focus capability, their least expensive rotating helical focuser looks good:

http://www.sciencece...s/html/4317.htm

You can attach it to this 1.25" nosepiece, and it could just sit between the diagonal and eyepiece:

http://www.sciencece...s/html/7316.htm

That is such an easy solution, but since it would have the same effect as a short extension tube, one would need plenty of extra in-focus room.

I was looking at a minimal-extra-length 'upgrade' focusing diagonal for short focal length finder-type scopes, and am gonna order these parts today:

DP36.4+4317 DP36.4 plus Borg #4317 focuser combo $109.00
Part #7316 - $25.00 (1.25" nosepiece for the Prism diagonal)

http://www.sciencece...is-acc/diag.htm

I emailed a query about the optical aperture of the DP36.4 prism diagonal, and Ted Ishikawa made a prompt reply that the prism optical aperture is 36.4mm, larger than 1.25" aperture. So for my needs that's a fantastic solution that would be a 1.25" focusing diagonal 'as short as it can practically be'.

It looks pretty feasible to attach the borg focusers (including the bigger-diameter expensive ones) to the input or output of baader T2 modular diagonals, so maybe that would be the way to go on 2" focusing diagonals (but getting a little bit expensive).

[Mike Conley]

Has anyone seen the Siebert model?

Mike

[jcjr]

The Seibert looks attractive (from viewing the web pictures). I was looking for the easiest way to have a helical focuser permanently attached to a diagonal, but for a drop-in focuser, the Seibert looks really good.

Seibert gets positive reviews re solid utilitarian machining. I like that design approach.

[arpruss]

Do any of these helical fine focus adaptors fit on the end of a 1.25" focuser, or do they all require a 2" main focuser?

[Lamb0]

Instead of $pending $80 on refractor or SCT parts, how about a 1.25" helical focuser adapted for 2" focusers, or a 1.25" focuser - without the high $ Rube Golderg 1.25"/oddball oddball/1.25" helical finaglety? After all, it's for a Newtonian Dob, not a Borg refractor, an ETX, or an SCT. The suggestion does work after a fashion for a 1.25" focuser - but a 2"/1.25" helical adapter would be more stable mechanically. Is there such an option?

[pferendzo]

I have one from Gary Wolanski... it's a great addition, much better than the Orion helical fine focuser.

http://members.shaw....ki/114FFADP.HTM

[Mike Conley]

I have one from Gary Wolanski... it's a great addition, much better than the Orion helical fine focuser.

http://members.shaw....ki/114FFADP.HTM

Does this model rotate the ep when adjusting?

Mike

[ccs_hello]

DIY version
CN post and CN article.

Clear Skies!

ccs_hello