Artificial star collimation

[gregbradley]

Has anyone used an artificial star to collimate their scope?

One like this:

http://www.astromart.com/classifieds...fied_id=699758

I was wondering if it were a worthwhile tool as seeing is a big variable in doing real star collimation.

Greg.

[multiweb (Marc)]

Made my own with some fibre optic left overs and a block of cardboard. This way I can have a little FOV and work out camera tilt, etc...

I also have an artificial star. It's handy because you don't have to guide and you're not affected by seeing. You can do this indoors too.

[DavidTrap (David)]

What distance do you use that at Marc??

Ta
DT

[multiweb (Marc)]

Originally Posted by DavidTrap

What distance do you use that at Marc??

Ta
DT

With my 8" newt at F/12 (barlowx3) approx. 8m.
With the C11 you need to be outdoors. At least 26m.

You can use this close up for a defocused field and square your camera but if you want to work out precise collimation or optical aberrations you still need the final star test at infinity.

This will get you very close though. Board is 140x150mm.

[DavidTrap (David)]

Ta
DT

[DarkArts]

I use the Hubble Optics artificial star. It worked for me at 22m for a 10" SCT.

Once well practiced, it's just as quick to collimate on a real star, but the artificial star is still useful for initial collimation after cleaning and replacing the corrector and/or secondary, fitting a new focuser, connecting a new camera, etc.

Practicing on the artificial star is a lot easier than practicing on a real one.

[loc46south (Geoffrey)]

Hi Greg - I used one when I was trying to image with a SCT - It gave good results. I found it worked best at about 4 times focal length - at night and I used to do it over a grass surface (Farmers Paddock) - there was less thermal interference from the ground.

Cheers
Geof Wingham

[gregbradley]

Great. Thanks for the replies. I suppose it assumes you can mount it several metres away and point the scope at it. My scope is permanently mounted so that may not be so easy. I suppose I could get it to look out the door.

Greg.