Focuser woes

[badgerchap]

Hi all,

 

Not sure if this is the right category for this question really, but then it doesn't necessarily fit anywhere I don't think. Anyway...

I have a TS Optics 6" F4 Newtonian which optically is great but its (2") focuser is absolutely woeful. It was bad when I got it, now it's almost unusable. It can be made firm, but whether it can be made firm at the focal plane accurately enough for imaging is debatable. Adjusting the focus for imaging is essentially impossible excluding luck.

I don't really have the cash to fork out for a decent focuser - at least not after forking out for my new C8 and building an Obsy. I am wondering, however, if I could use a helical focuser (such as that linked at the bottom of this post) attached to my current focuser? I'd fix the current focuser roughly in place and then use the helical for fine adjustment.

I'm worried a) about reaching focus, b) misunderstanding the purpose of helical focusers (which I've never used).

Any help would be appreciated, including alternative ideas! Thanks,

 

Guy

 

https://www.rothervalleyoptics.co.uk/baader-125-helical-focusing-eyepiece-holder-t2.html

[Moonshane]

You could use something like that but I'd check if it is a rotating or non-rotating unit.  Depending on your 'spare' focus travel something like this might be good.

https://www.365astronomy.com/365Astronomy-1.25-Non-rotating-Helical-Micro-Focuser-with-T-thread-and-0.05mm-Scale.html

[Zakalwe]

25 minutes ago, badgerchap said:

Hi all,

 

Not sure if this is the right category for this question really, but then it doesn't necessarily fit anywhere I don't think. Anyway...

I have a TS Optics 6" F4 Newtonian which optically is great but its (2") focuser is absolutely woeful. It was bad when I got it, now it's almost unusable. It can be made firm, but whether it can be made firm at the focal plane accurately enough for imaging is debatable. Adjusting the focus for imaging is essentially impossible excluding luck.

I don't really have the cash to fork out for a decent focuser - at least not after forking out for my new C8 and building an Obsy. I am wondering, however, if I could use a helical focuser (such as that linked at the bottom of this post) attached to my current focuser? I'd fix the current focuser roughly in place and then use the helical for fine adjustment.

I'm worried a) about reaching focus, b) misunderstanding the purpose of helical focusers (which I've never used).

Any help would be appreciated, including alternative ideas! Thanks,

 

Guy

 

https://www.rothervalleyoptics.co.uk/baader-125-helical-focusing-eyepiece-holder-t2.html

Have you "tweaked" the current one? Astronomy Shed has guides on how to improve a standard focuser.

They usually can be improved to a fair degree with some gentle tweaking.

[Moonshane]

True!

 

[Zakalwe]

Here's another one for the newer GSO focusers:

http://polluxchung.com/gso_crayford_fix/

Edited July 21, 2020 by Zakalwe

[badgerchap]

Yeah so after posting this I decided to grow some b***s and open the focuser up. Four tightened screws later and it's like a new unit.

 

Thanks chaps!

[Moonshane]

Top man!