Telescope Reviews: Re: What kind of a focuser should I use on a C8-plus?

A few choices ...

Starlight Instruments Feathertouch Microfocuser - replacement for existing (or non existing) focuser knob assembly. Really smooth dual speed setup. Keeps the weight down and doesn't extend off of the back of the scope to interfere with the base when you're pointed at the zenith.

WO, GSO, others - lower priced dual speed crayford like external focusers. Good price points, solves coarse focusing problems but in your case you'll still need to fix that stock focuser. External focusers have a limited amount of focus travel ... much less than what's available with the built in version (moving the primary mirror and having a 5x magnification on the secondary mirror makes for lots of focus travel). The other issue with an external focuser is that they make it almost impossible to use an F6.3 reducer/corrector. The extra length of the focuser doesn't allow many configurations to come to focus with the reducer/corrector in place.

JMI, Starlight (Feathertouch), Moonlite, Optec and others - premium focusers with all kinds of bells and whistles. Same issues as the ones above, except the Moonlite which has an option for mounting the reducer internal to the focuser. Premium means 2x and more of the price of the WO, GSO focusers.

So if you are just missing the rubber knob but the focuser mechanism is still in place then you can likely find some form of replacement knob, and then get the external WO, GSO external crayford (do check how much clearance you're going to have with the new focuser between the base and whatever you're going to hang off of the new focuser.

If the focuser mechanism itself is missing (no brass post) then I'd absolutely go with the Feathertouch Microfocuser since it will solve two problems at once (stock focuser replacement and dual speed capability).

Personally I like the Microfocuser just because it's the simplest solution and just as inexpensive as the basic external crayfords, I have one on both of my SCTs.

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Mark

C11, C6, APM/TMB115, and AT80ED
Tandem mount CGE and CG-5A, WO EZ-Touch, and AT Voyager
25x100s, 8x56s, T-Mount Light, and Mark 1 eyeballs
Modded 350D, DSI-P, SPC900, and Mallincam

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