SCT WO Crayford doesn't screw all the way on?

[cmr]

Hi,

I have a WO Crayford Focusser for my C8 SCT - I also have a Bintel Crayford Focusser - Need to decide which one to keep, and also settle my mind about their strength etc.

They are a both in great condition and both pretty much seem to work the same (10:1 etc) however the Bintel one screws all the way on to the visual back - the collar is then flush with the rear of the scope- the WO one has a silver collar and only screws part way on to the thread before it runs up against an internal 'stop' and has no more thread anyway - (see images below)

They both SEEM to be secure on the rear of the C8 and cope with a 2" diagonal and some hefty eyepieces OK but I am wondering is this usual with WO SCT Crayfords?

I also just got a focus motor and it only fits that WO not the Bintel (Bintel shaft is thicker!) so I'm planning to keep the WO - any comments or advice?
:help:
Thanks

Chris

[cmr]

Oh - I can't just swap the collars, tried that , the BIntel one has a a slightly too big 'flange' to fit in to replace the WO one!

[traveller]

Hi Chris,
I think you may need an adapter for the WO focuser, others will know better.
On a related noted, which one is better operational wise for your 8" SCT?
I am after a 2" 10:1 focuser, so happy to grab the left over from you once you decide which to keep ;).
Cheers, Bo

[cmr]

HI - They both seem fine - just as 'light' to the touch for the extra fine focus, and ok for the normal wheel too - both seem well made etc. - The WO was the right size to fit the electric focusser I had wheras the Bintel 'axle' was thicker - otherwise Id just keep the Bintel. (though Im sure I could make/get something to make the focusser fit to the bintel axle)

[traveller]

Does that mean you MAY want to part with the WO focuser???
Care to PM me with a price?
Cheers, Bo :D

[wasyoungonce]

Just had a look at the WO site and images of their SCT focusers show that lip (http://www.williamoptics.com/accessories/SCTcrayford_spec.php#)...which is preventing it fully being screwed down.

It's just the way its made...bummer....although it won't hurt.

[kustard]

I have the WO focuser on my C9.25 and it's the same as your C8. It has no effect on my observing.

[Barrykgerdes]

There are two different threads used for the back plate on SCT's and Maks depending where they come from The Bintel crayford is slightly smaller than many of the "cheap" OTA's and won't screw on more than a couple of threads.

I could not get the back plate off my OTA to put it in the lathe to recut the thread so I opened out the thread on the Crayford instead.

Barry

[cmr]

thanks guys , good to know your c9.25 is the same with no problems..

[Dave47tuc]

Hi Chris,
The focuser and I have just checked did not sit flush up on my scope either but it did not affect anything. see picture.

[cmr]

thanks dave - seems all is fine then - just one of those differences you notice when one has two similar items that youd never realise unless theyre seen side by side -

its now happily affixed with the accufocus motorfocus attached and all seems great - plusnbintel crayford sold - so now to wonder about making eyepies and a toucam parfocal!
cheers chris