Helical Focuser question

[strayring]

Hi, I have a single speed Crayford on an Orion XT8 f5.9 dob. Would a helical focuser work with this scope? And, would it make fine focusing easier?

Any opinions or help appreciated.

Ray.

[Moonshane]

Assuming you have enough in focus for the focal length of the helical and you buy a good quality helical then yes it would work. That said, for a good helical, you might be able to get a good dual speed like the Baader for not much more.

[vlaiv]

If you are looking for a cheap upgrade to dual speed, have a look at this:

https://www.teleskop-express.de/shop/product_info.php/info/p2625_1-10-micro-transmission-for-retrofitment-of-Crayford-focusers.html

I've fitted it to my Skywatcher 8" dob, and it works great, quite a difference on fine focusing for planets.

[Geoff Lister]

I fitted the same Lacerta retro-fit unit to my 10" Dob. It was easy to change and makes focus much easier at higher magnifications.

Geoff

[floyd fan]

The thing I found that made a huge difference to focusing on my scope was putting a variable speed motor drive on it. It meant I didnt even have to touch the scope and could quite easily fine tune it.

[Saturnalia]

On 24/07/2018 at 11:29, Geoff Lister said:

I fitted the same Lacerta retro-fit unit to my 10" Dob. It was easy to change and makes focus much easier at higher magnifications.

Geoff

I agree - it's also available in the UK from 365 Astro (cheaper postage than getting it from Germany):

https://www.365astronomy.com/Lacerta-Dual-Speed-1-10-Microfocus-Upgrade-Kit-for-Skywatcher-Crayford-Focusers.html

[niallk]

+1 for the Lacerta Simple to install, works superbly!

[Cosmic Geoff]

My Helios 203mm f5 Newtonian has a single speed rack & pinion focuser. I added a Chinese helical focuser (apparently intended for guidescopes) which screwed into place, replacing the 1.25" adapter end of the 2"/1.25" adapter. 

As indicated, the helical focuser just screwed into place, and cost me about £20.  It works well to give a fine adjustment, except that the grease in it seems a bit stiff in the cold, and was far cheaper and less troubling than changing the whole focuser for a 2-speed.  

[strayring]

Hi Geoff. I haven't done anything about fine tuning my focuser yet. I am still wondering about those Chinese helical types that you're using.

Could you possibly send a photo of the one you have, it may be the answer I'm looking for on my 8" f5.9.

Thanks Ray.

[Ceramus]

Got The Lacerta kit for my 300p flextube, great improvemnt and easy to fit.

[Cosmic Geoff]

I think this is the same as the one I got. https://www.ebay.co.uk/itm/Metal-High-Precision-Double-Helical-Focuser-for-1-25-Telescope-Finder-Scope-new/183331205902?hash=item2aaf64330e:g:Lc8AAOSwzyBbl32l:rk:7:pf:0

It screwed into half of my 1.25"/2" adapter.

[strayring]

21 hours ago, Cosmic Geoff said:

I think this is the same as the one I got. https://www.ebay.co.uk/itm/Metal-High-Precision-Double-Helical-Focuser-for-1-25-Telescope-Finder-Scope-new/183331205902?hash=item2aaf64330e:g:Lc8AAOSwzyBbl32l:rk:7:pf:0

It screwed into half of my 1.25"/2" adapter.

Thanks very much I will check it out. 

[OpusElite]

On 19/08/2018 at 10:57, Cosmic Geoff said:

My Helios 203mm f5 Newtonian has a single speed rack & pinion focuser. I added a Chinese helical focuser (apparently intended for guidescopes) which screwed into place, replacing the 1.25" adapter end of the 2"/1.25" adapter. 

As indicated, the helical focuser just screwed into place, and cost me about £20.  It works well to give a fine adjustment, except that the grease in it seems a bit stiff in the cold, and was far cheaper and less troubling than changing the whole focuser for a 2-speed.  

These forum posts are timeless. I am researching adding a helical fine focuser to my Newt, so it's been great to find that someone has previously done so. I was cautious about the intended 'guidescope use' and also whether it actually fitted correctly.👍