Focus using CCD instead of eyepiece?

[rubecula]

I seem to have got myself in a bit of a mess.  I've added a motor focuser to an EdgeHD scope.  In doing so I have moved the mirror somewhat and lost the focus position. Is there any way of getting the scope in focus without removing all the imaging gear and using an eyepiece?

I've tried using Frame and Focus in SGP,  moving the mirror with Focus Control using coarse steps of 500 and 200 but failed to find any stars in the region of the Milky Way.

Hopefully there is something obvious I've failed to think of.

Thanks

[Helen]

You could start with the moon 😊

Helen

[vlaiv]

Moon is excellent suggestion (as it is very bright and hard to miss), but in principle you need a fairly bright star and longer frame and focus exposure.

When you have star light out of focus it will spread over larger surface and signal on each pixel will be very low - that is why you need long exposure, but principle is simple - you will get a large doughnut from a bright star - or very very large circle with soft edge from the moon.

Make a turn of your focuser and see if doughnut / circle increase in size or decrease - go in direction of decreasing size until you end up in a single point for a star or sharp moon disc for the moon.

[Cosmic Geoff]

Good luck with getting focus without using an eyepiece. 😐  Every time I use a (planetary) camera, I start with focusing on the target via an eyepiece, make a coarse adjustment to accommodate the difference between the focal planes of eyepiece and camera, and then put in the camera with the telescope aimed at a really bright object that will be picked up even if well out of focus.

I need the eyepiece in place to align the GoTo anyway.

[rubecula]

Thanks all for your help.  Helen, the moon had just gone behind trees when I went out but tonight or tomorrow it should be better (if the forecast for clear skies doesn't change).  Vlaiv thanks for your input, I'll increase the exposure when I have a go again.

 

[carastro]

Does your camera and SGPro enable binning as the download is faster so you can see to focus more easily.   Don’t forget to put back to non binning afterwards. 

[Star101]

The moon is a great suggestion if you know you are pointed at it!! Else, when not sure, you may find yourself spending more time looking for the moon than actually trying to focus.

Can I suggest, point the scope at the milky way as there is a huge starfield. Wind the focuser to one extreme then slowly move to the other extreme. And as carastro suggest, use 2x or higher binning, if possible. Although, my Atik 4120ex will not work with SGPro 2x or greater binning. Although it does work very well with Artemis Capture at 4x binning.

 

[rubecula]

Carole, I binned it 2x2 last night but when I try again I'll set it to 4x4 and see if that helps.  Although I haven't used the scope for 6 weeks or so the GoTo looks fairly good.  I aimed at Cassiopia last night and it was certainly pointing in the right direction. Next time I'll try for the moon to begin with.  I'll get out a bit earlier to make sure it's still visible from the garden.

[rubecula]

Success!!  All in focus now, which I suppose means the end of clear nights,

Thanks all,