Crayford V rack and pinion

[Gary70]

I was wondering about the differences between these two focusers,

I read in descriptions and reviews about how a certain instrument benefitted from a nice crayford focuser or how the rp focuser gave smooth non slop action.

Is the crayford so great? I still see many new scopes being supplied with rp especially in the larger ones so it just a cost thing?

I have only used regularly the rack and pinion I find it very adequate and have very little experience of crayford but wonder if I am missing out on something that could improve my nights out?

[NGC 1502]

I think that both types of focuser work just fine if they are well engineered.

But that's the point - well engineered.

Not all Crayfords are good, not all R&Ps are good. I'd sooner have a top notch R&P than a dodgy Crayford.

But I'm not super fussy, and not an imager, so I've found that all the different focusers I've had could be tweaked into acceptable performance for me (but maybe not everyone)

Fixes have included adjusting the various screws, adding thin teflon tape, careful lubrication.

Regards, Ed.

[Grotemobile]

I have got, rack & pinion on my 4" refractor.

It is not as smooth as the Crayford on my other

scope.The Crayford has a fine tune,which i find

very good for imaging. I think it is,horses for

courses,to be honest.

Steve.

[Zakalwe]

<taps fingers on desk, checks watch>

Olly will be here any minute now.....

[glowjet]

I overheard someone say that he was on holiday at some Astronomy centre in France

John.

[Zakalwe]

A bad focuser is a complete PITA, regardless if its a Crayford or rack & pinion. A good focuser can transform a scope making it a pleasure to use.

Rack & pinions got a bad press, probably as there were so many rubbish ones about. The Crayford is easier to machine, hence cheaper. But a good r&p is probably the best. There are good Crayfords out there- Moonlites, Baader Steeltracks are good.

[Gary70]

Well informed opinion as usual,, thanks guys.

I googled RP focusers for more information and as usual it brought up a link for this forum

Thought i'd link it here might be useful to any other "new" guys.

[ollypenrice]

My mild dislike of the poorer Crayfords comes from their having the following insignificant drawbacks;

Not working.

Working until you are about to start an exposure and then not working.

Looking very pretty and being nice and smooth but still not working!!!

Moonlite, Feathertouch and Baader make Crayfords which work. These cost far too much to go on budget scopes so budget scopes are sold with Crayfords so bad that they should have the Trade Descriptions Act hurled at them.

I would far rather have a simple single speed R and P such as I have on my TeleVue Pronto than a pretty slippery Crayford two speed. If I want to image with a single speed R and P I just attach a long wand or lever to the knob. Works a treat and doesn't slip. Crayfords are OK on Dobs where the focuser is always horizontal and isn't holding a heavy camera.

There, that was pretty mild wasn't it? Bet you're all disappointed by the

lly

[wrinkly]

Realise I might get banned for this. Who said "Good."?

Do Crayfords work best in Crayford? If so, will start investing in Kentish housing stock.

Okay! I'll get my coat.

[michael.h.f.wilkinson]

Amazing, Olly. So have you taken an anger management course, or are you on New medication?

[Zakalwe]

lly

That was very Zen-like of you (Zen and the Art of Focusing??? :grin: )

[ollypenrice]

That was very Zen-like of you (Zen and the Art of Focusing??? :grin: )

Nope. I had my fingers crossed!

No change in the medication - which comes from the Rhone valley about fifty miles to our west...

Olly

[michael.h.f.wilkinson]

Ah, the good old prescription of Cote du Rhone, or was it Chateauneuf du Pape. Really good for the nerves. Single malt whisky does a similar job.

[E621Keith]

Get a helical focuser. It's does not require tension knob adjustment regardless of load and it's always the right way up when used in an equatorial mounted scope (except Newt)

It feels a bit odd at first, but after you got used to it you will wonder why don't every scope comes with it.

I agree with what others said about workmanship. Moonlite and FT Crayford are very good, I'd rate them the same as Borg helicals. They are smoother and require less forces, but require tension adjustment when swapping between light and heavy eyepieces.

At the other end of the spectrum, William Optics's DDG is worse than the basic R&P on a SW refractor. The DDG's focusing action feels spongy, I can deal with backlash, but that spongy feeling between engaged and not engaged really put me off. I've also came across an old GSO single speed that was truly horrific.