MotoFocus

[peter.h]

Hi anyone have an opinion on focuses...I'm looking at either;

Optec TCF-S2i or JMI EV1CM DROEV

I have a C9.25 SCT and want to control from my laptop

Cheers,

Peter

[multiweb]

Have you looked into the Sharpsky Pro kit? I have one fitted on the microfocuser of my C11.

[peter.h]

Thanks Marc will do

[AlexN]

I've just finished building my own based on the SGL observatory automation group design. Cost me $38 and 4 hours of fiddling to get it going. Ascom compliant and all. No temperature compensation yet but I am pretty sure I know how to add it.

[The_bluester]

Marc, how does the C11 do for image shift using an electronic focuser? There is always visible mirror shift with my C925 when I change focus.

Does it have an impact or does it move focus slowly enough that with an OAG (Which will also see the image shift) the movement is guided out? And what do you focus with, a guide cam after matching focus with the main imager?

I am not on that slippery slope yet (AP) but always keeping an eye on things for ideas.

[multiweb]

Very minimal at F/10, non existent with the hyperstar. You usually get shift when you change focus direction but it's likely during the night the temperature will drop continuously during your imaging run. It's pretty rare to have wide fluctuations up and down in temperature.

I've never checked if the OAG ever lost the guide star due to refocusing while imaging but I doubt it very much. At F/10 the star moves more due to seeing than any mirror shift.


I use a lodestar and PHD.
Pic of rig set up at home below.

[The_bluester]

Looking at your setup, pretty much as I envisaged, I imagine that the rate of change for any focus changes would be small enough that any image shift would simply be guided out.

As you said, I suppose it is likely to be largely in one direction in any case so image shift would not be a great issue.

[peter.h]

Thanks all for your feedback and guidance...:)

[bugeater]

Now that seems neat. I think I need to give it a go. Time to dismantle my arduino driven barn door tracker

[AlexN]

It was really easy mate. Took half a day to get it going and it works brilliantly.

Mine is belt driven so it's easy for me to disconnect it if I want to focus manually... I was planning on making it direct to the shaft.