Sharpcap for collimation?

[Moonstruck]

Hi,
Can Sharpcap be used for collimation? If so, where can I learn more, and possibly get detailed instructions or a tutorial? I watched Michael Owens tutorial on using planetary livestacking (which was great) and he mentions that it can be used for collimation, but I didn't see any specific instructions on using it. It's a long video, and I didn't watch the whole thing, so maybe I missed that segment?

[admin]

Hi,

there are various bits and pieces that you can potentially use in SharpCap to help with collimation...

* An 'experimental' collimation tool that works on the distribution of star sizes across the frame - this works best with Newtonian telescopes as the coma off axis is easily detected, but if you add a coma corrector then it is much less successful

* The various reticule tools, including the circular one and the multi-reticule tool.

I think Mike does something based on the reticules to help spot whether the out-of-focus star rings on an SCT are central and symmetrical or not, but I'm not 100% sure. The other approach based on the reticules is to place a camera with a wide-angle meteor lens inside the eyepiece holder. Then you see the inside of the telescope (with reflections of primary , secondary, etc) in view and you try to get them all lines up as you would with an OCAL collimator.

You may also want to investigate a tri-bahtinov mask - this can help get pinpoint collimation like a normal bahtinov does for focus. Nothing specific in SharpCap to support this though...

cheers,

Robin

[Moonstruck]

Thanks.

I am particularly interested in using the planetary livestacking function to try improving collimation. Mike stated that the planetary livestacking tool can be used for collimation, which got my interest, but I didn't hear anything further on it in his video. But like I said it is a long video, and I might have missed it.

I read somewhere else that the planetary livestacking tool can be used for collimation by using a planetery moon (i.e., one of Jupiter's moons) and looking at the stacked diffraction rings. If you by chance hear anything further on this, can you please advise?

Thanks again,
John

[admin]

Hi John,

Mike posts here on the forum as @borodog, so have a search to see if he has posted anything here about it. Now that you mention the planetary live stacking, I have a thought that maybe he was using it on the diffraction rings of a star (or maybe a moon?) to help stabilize the image so you can judge the collimation a bit more easily than with the pattern jumping all over the place.

cheers,

Robin

[Moonstruck]

Yes that makes sense. I'm going to try that soon (focusing on one of Jupiter's moons, then livestacking to try to see the diffraction rings around the airy disc. If I can do that, it will give me a good idea how far out of collimation my scope is.

I have seen a lot of Borodog's posts on the CN planetary forum and he is an excellent planetary imager (one of the best)! Nice to know it is the same guy (Mike) in the video.