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Non rotating helical focuser????


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Google has thrown up the #7315 Borg focuser ( about 100 gbp with a front end T thread adaptor!!) but not much else.:)

Anyone come across a "cost effective" NON rotating focuser for a refractor ( ie fits to T thread or 1.25")?????

Let me know.

Ken

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Peter,

The TS one is the Borg one....

The other two I think are rotating versions, not NON rotating.

Ken

Edited by Merlin66
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Hiya Ken, if you are handy with hand tools as i suspect you are, then have a look out for very cheap Zenit camera lens's. Rip out the glass and other unwanted bits and bobs, you will have a non rotating helical focuser. You may need a couple of types as I found some better suited than others.

Bob

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Russ,

SCS show 87gbp plus 6gbp postage, and you need an adaptor, minimum is 19gbp....it soon adds up.

Ken

Ah, they have put up the prices since i last looked (2006). Used to be £69 for the main unit and £15 for the adapter and a few quid postage. Not looking cheap then Ken?

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As Wobbly Bob suggested, camera lenses can make excellent helical NRO focusers I've made several for different purposes. Look for ones with sufficient aperture through the focusing system. The only downside is that they don't seem to take much weight before becoming a bit stiff.

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Guys,

Appreciate your input.

Camera lens would be an alternative, if I only needed one for myself, could be a good solution; the problem is I need a robust solution to be able to supply up to twenty units! ( Stage 2 PST mod)

Ken

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  • 3 weeks later...

AE to an Adjustable T mount which is a non rotating helical focusser with a male T thread on one end and a female T on the other... that can be locked off at any length... It might be a bit coarse or too long or you application though... it could be shortened by a few with some additional machining

FLO sell it fro £39 but i picked one up dirt cheap on Astroboot... (sorry FLO)

Adaptors - Variable extension tube 45mm to 66mm

Peter...

Edited by Psychobilly
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I tried that before I found a suitable SCT focuser. It works, and has a suitable range, but as you say, very coarse. Still, as a stand-in/budget piece it does the job.

Andrew

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I am planning to use it to dial in the spacing for my SCT FR + OAG setup I'll then machine up a custom one or get it done for me..... it only cost me £13 (even better) from the boot so was worth a punt ...

Peter...

Edited by Psychobilly
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I am planning to use it to dial in the spacing for my SCT FR + OAG setup I'll then machine up a custom one or get it done for me..... it only cost me £15 from the boot so was worth a punt ...

Peter...

Aye, it will do just fine for that, but trying to achieve focus when imaging will just end in tears.

Andrew

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Indeed... which is why I will be using the electric focuser on the SCT for that...

Thisis just easier than stripping the setup and adding various combinations of T adaptors and shims together to alter the spacing...which would invariably alter the camera orientation as well making comparisons even more painful... :)

Peter...

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Indeed... which is why I will be using the electric focuser on the SCT for that...

Thisis just easier than stripping the setup and adding various combinations of T adaptors and shims together to alter the spacing...which would invariably alter the camera orientation as well making comparisons even more painful... :)

Peter...

Makes sense... Presumably you will go back to a combination of T-spacers (when you've determined the correct spacing) to reduce slop?

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No i'll make a prorotype single piece one to exactly the lenght I require... and then get my friendly local precision enginnering shop to make it for me at trade rates :)

What slop.. I have already had it apart and sorted that out :icon_scratch:

Peter...

Edited by Psychobilly
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