Micro focuser help

[jackp93]

Hi all

 

Sorry if this is a bit of a silly question, but I have a skywatcher sct and the focuser on it is a bit rough so I have been looking at upgrading it. I have found the below helical focuser would this work or would I need to buy one of the Crawford style ones.

https://www.ebay.co.uk/itm/Starguider-T42-Telescope-Micro-focuser-set/383194718190?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20160908105057%26meid%3Dfdd85f5a997b403185b5624fe8eca5e3%26pid%3D100675%26rk%3D3%26rkt%3D15%26sd%3D273385240847%26itm%3D383194718190%26pmt%3D0%26noa%3D1%26pg%3D2481888&_trksid=p2481888.c100675.m4236&_trkparms=pageci%3A601215b0-e826-11e9-ad28-74dbd180a6f8|parentrq%3Aa0ac5a5616d0a4e922b77061fff89d2e|iid%3A1

Thanks 

 

Jack

[Davey-T]

Probably be better off with a Crayford design that one appears to be limited to 1.25 eyepieces and it's sometimes useful to use 2" eyepieces in SCTs depending on the size of the scope.

Dave

[johninderby]

Do you mean a Skywatcher Mak?

Anyway that helical focuser isn’t very good if used horizontaly. Much better if used vertically in the top of a diagonal.

This Baader prism diagonal has a micro focuser on the top.

https://www.rothervalleyoptics.co.uk/baader-prism-diagonal-t-2-90-with-focusing-eyepiece-holder-and-125-nosepiece.html

[joe aguiar]

U can get the Crawford focuser for sct types but it's pretty bulky and big if u got the fork mark scts, and by time u put 2 "diagonal it may bump the base.

Best bet is get the feather touch micro focuser. It replaces the oringinal with a dual speed. Every size and model sct has a specific model that will fit.

It's easy to install costs about 250 USA but worth it instead of doing a big bukly rear sct Crawford

Look it up and u will see 

Joejaguar 

[jackp93]

Hi

Thanks for the reply’s. I had looked at the featherlight ones but they are out of my price range, the Crawford ones are only just in it. As I’m still very much learning, would the helical one work on my 127 without having to buy any other parts as it’s only £25. Then once I’m a bit more accomplished upgrade to one of the better focusers.

 

thanks

 

Jack

[johninderby]

The problem with this cheap one is that it rotates as you focus which means that it has to go on the top of the diagonal which is a problem if your diagonal doesn't’ have  a T2  thread on the top. If it doesn’t you would need to buy a T2 to 1.25” nosepiece to allow the focuser to fit into your diagonal.The eyepiece will rotate as you focus. 

You would need a non-rotating helical focuser if you wanted to fit it between the scope and the diagonal.  Having the diagonal rotate as you focus just wouldn’t work

Something like this. Lot more expensive though.

https://www.ebay.co.uk/itm/ZWO-1-25-Helical-Focuser-with-T2-Connection-non-rotating-System-ZWO-HF1-25/372784265184?hash=item56cbac77e0:g:lDIAAOSwKRJdjGuA

[Merlin66]

I successfully use the Borg Helical focusers on all the Spectra-L200 spectrographs as well as the Spectroheliograph and PST Mods.

 

[joe aguiar]

I would use the one comes with then

Joejaguar