Focusser for Celestron 925 SCT?

[dc509]

Hi

Can anyone recommend a focusser for a Celestron 9.25 SCT? It is already clear to me after only a few outings that the supplied mechanism is difficult to get accurate focus with. I see loads of references to Crayford focussers but am not sure if they are suitable for SCTs, or if they are, is there something specific to look for?

Many thanks

Duncan

[m.tweedy]

I use a WO crayford on my C8 and find it very good

[SteveP]

Duncan

It's not unusual to have a less-than-accurate focuser on an SCT. Their design of moving a large, heavy primary mirror can result in focusing errors. I used a WO 2" focuser on my Meade 10". It was a heavy duty versopn so that it could handle the weight of a camera and other stuff on the end of it. The one feature I'd recommend is that whatever focuser you choose, it is a dual speed version, ie with both coarse and fine cfocusing capabilities.

If you look around, you'll find focusers specifically for SCT's which screw onto the the visual back thread

HTH

Steve

[brianb]

you'll find focusers specifically for SCT's which screw onto the the visual back thread

Which have their own issues in terms of unbalancing the tube & preventing access to the zenith, if using a fork mount.

Starlight Instruments (Feathertouch) make a replacement focuser knob with 10:1 microadjustment, this gives terrific control & does not have balance or fork clearance issues. It's expensive but IMO very much worth the money.

[Daz1969]

WO Crayford on my C8 too. Very pleased

Daz.

[arad85]

WO crayford here too on my C9.25 on a EQ6. Very pleased here too

[Brinders]

I have a Smart Astronomy (GSO) dual speed crayford focuser on my CPC925GPS, which is fork mounted, and I have no problem at all at the zenith with a 2" WO diagonal fitted or my Neximage web cam or Pentax K20D DSLR, although clearance is tight with my security camera.

Brinders

[todd8137]

Which have their own issues in terms of unbalancing the tube & preventing access to the zenith, if using a fork mount.

Starlight Instruments (Feathertouch) make a replacement focuser knob with 10:1 microadjustment, this gives terrific control & does not have balance or fork clearance issues. It's expensive but IMO very much worth the money.

what if this is pier mounted ?

[m.tweedy]

The pier just replaces the tripod so either just fit onto the top of the pier instead.

[Monty]

I use the skywatcher crayford with a dovetail bar and a counter weight from ADM. Only time I have a zenith problem is when I use the focus reducer for photography.

[Stu_2011]

I use the skywatcher crayford with a dovetail bar and a counter weight from ADM. Only time I have a zenith problem is when I use the focus reducer for photography.

I have the same and the focuser is fine, I've added a JMI electric focuser to the Crayford and it's really good. Couple this electric focuser to the HitecAstro DC focuser unit and you have a super controllable unit with very fine focus capability.

I just do planetary imaging with my SCT so the zenith issue isn't really a problem.

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