Helical focusers?

[pakarinen]

Put a Crayford on my ST80 and I love the thing - so much nicer than the stock R&P. So, being spoiled now, I was planning on putting a Crayford on my ST120. Not having the spare hobby cash right now though, I was looking at the Astromania helical 1.25-in focuser.

Any opinions? I figure for $35, it's not much of a loss if it doesn't work well and could potentially be a stopgap until I get a Crayford. I'm aware that change of focus can take a lot of twisting.

Thanks.

[Lady Fraktor]

Most of these are limited travel so if using it as a add on to your current focuser they work quite well.

[Bigzmey]

I think you will be better off saving money towards Crayford. As Gabby indicated helical focusers don't have enough range to serve as main focuser. If you add it to your existing focuser it will require ~2" off in-focus travel which your ST120 does not have.

[helicon]

Another vote for the Crayford. I swear by this kind of focuser.

[avid.astronomer]

Some people swear by helical focusers... I swear *at* them. The Crayford is definitely worth saving up for, unless, as Gabby says, you intend to use the helical as a focal extension.

[John Baars]

I have them as an add-on on my prisms/ diagonals, not as a main focuser. There is not travel enough for acting as a main focusser.
It works great, even the fine tuning of a f/5 telescope is flawless, hairsplitting exact. You must have enough in-travel,for it adds a bit extra height.