Electric focuser Coronado

[gcluer]

Has anyone adapted a commercial electric focuser for a Coronado PST?

[Peter Drew]

Not as far as I know on a standard PST, I'm sure it has been done on a PST mod to a larger donor telescope where a r & p or Crayford type focuser has been used. The small standard PST focus knob doesn't offer much to play with and the action is not particularly precise, not a very good candidate for motorising. 

[NGC 1502]

 

Has anyone adapted a commercial electric focuser for a Coronado PST?

Not what you are asking, but this accessory http://www.harrisontelescopes.co.uk/acatalog/CMC_PST_Focus_Knob.html gives better focus control than the supplied small PST focus  knob.

Regards, Ed.

[JamesF]

Well, err, kind of

But mainly by replacing the "black box" altogether.  I used a Revelation dual speed SCT focuser, made up a new mounting plate to accept the gold tube and put the eyepiece section from the black box into the top of a standard diagonal.  Then I modded a Skywatcher motor focuser kit to fit the SCT focuser.

After the first mod it looked like this:

And then with the motor focuser:

James

[JamesF]

Here's a thread with details of the first mod: http://stargazerslounge.com/topic/187570-pst-stage-05-mod/

Just trying to find the motorised bit now.

James

[JamesF]

Ahhh, here it is: http://stargazerslounge.com/topic/212551-revelationskywatcher-sct-dual-speed-crayford-motor-drive-conversion/

James

[JamesF]

I also have motorising the etalon tuning ring on my list of things to do, but I've not worked out how yet.

James

[gcluer]

Answering my own post - I fitted a JMI Microfocuser (the one designed for the Celestron 6SE).  This required drilling two small holes in the PST to fix the motor.  This was in an area well away from the etalon and you can remove the telescope's side plate so you can see what you are risking drilling into.  I threaded these holes but a nut on the inside would have worked just as well.  The connection between the moving part of the focuser and the focus know is made by fitting a walking pole ferrule over the focus knob.  It needs cutting down just a little to get the fit into the focuser.

[DJay]

I recently purchased the Coronado PST and achieving a fine focusing is difficult with focusing knob provided.

How has your solution with the JMI Microfocuser been working?

[Merlin66]

I use a Vegemite lid ......

Just cut a central hole to tightly fit over the PST knob... it gives you much better fine control, and it's cheap!