Artificial star collimator tool

[Carl]

Just got an RC8 scope. Dont really want to perform acrobatics in my observatory leaning over the front of my scope and dropping hex keys on the mirror.
Have seen advertised at OPT the 2 following artificial star collimators claiming that you can do the collimation without being hindered by atmopsheric conditions.
1.Astrozap
2. Hubble 5-star collimator

How accurate are they? I can afford to buy either, and for the price i just cant be bothered attempting to make one.

Any assistance and opinion much appreciated

[Grahame]

Gday Carl,

I have used the hubble star collimator - needed about 40 meters distance to get it focused on the RC10 scope but once i got the distance sorted it was a good aid to initial collimation.

The only problem is the scope is sitting horizontal so any mirror movement could become an issue - as always star testing is best once initial collimation has been done with this :)

Grahame.

[Merlin66]

I like the hubble artificial star torch. Gives a wide range of star sizes ( to suit different scopes at different distances). Does what it says on the lid.
Recommended.

[cfranks]

I bought the AstroZap and the batteries were dead out of the box. Not a problem, just someone accidentally left the unit switched on when they packed it. I had to open the unit to replace them and saw what is probably the most cheap construction I have ever seen. The switch was intermittent but there was a second Pole so that was easily fixed. Everything was glued in place by great gobs of glue. The light source (LED I think) is not aligned to the pinhole and the resulting Artificial Star is nowhere near uniform in its light. They recommend 200 feet for the distance and I haven't been able to try it for collimation yet.
Apart from that, it's not too bad! :)

Charles

[troypiggo]

Wow. Great sales pitch. Do you work on commissions? :lol:

[allan gould]

Carl
Have a look on IIS for Als collimation aid. I've recently purchased a 10" GSO RC and found that using a real star and ccd camera I was able to get fairly close to collimated but I suspected I was out a fraction. This was confirmed but using Al's collimation aid and I was able to tweak it just to perfection which is what these GSO scopes require. I've Used nothing else for my SCT. And RC scopes and found it is the simplest and quickest means to get perfect collimation.

[erick]

Agreed. And pretty cheap. And hassle free, compared to trying to make your own - which I have done with a bright LED and optical fibre.

But the scope is collimated horizontally which might not be the best for every scope.

[Merlin66]

Eric,
Only if you don't mount the torch high up in a tree or near building.:lol:

[erick]

I've often thought about it, but 1) you need a good distance from scope to torch and 2) why would I set up close to a tall tree or building and block out part of the sky! :D

But I would really like a way to be using it with the dob at about 45 deg elevation.

But I am just about to go out and try it with my 8" SCT horizontal.

[Harpspitfire]

im not sure id buy anything, i use a simple led flashlight, i cover it with a cylinder item having a 1mm hole (using electrical putty) i set it about 100yds away and collimate at 600X- its only a $1 for the flashlight, i even can do this before it even gets dark

[Merlin66]

There's a big difference between a 1mm hole and a precision aperture of 25 or 50 micron.

[erick]

Hubble torch made collimating the SCT so easy last night.

[Carl]

Hey Erick
Did you collimate with the scope horizontal?
I ask this becuase my RC8 is not supposed to have issues with mirror flop like the SCT's

Cheers Carl

[mikerr]

Is this the Hubble device being referred to?

http://www.ebay.com.au/itm/Hubble-5-star-Artificial-Stars-All-Telescopes-/200670876533?pt=LH_DefaultDomain_0&hash=item2eb8ea9375

It seems to be quite reasonably priced!!

I have an orange tube Celestron C8 and might give this a go.

Michael

[Carl]

Yep
Thats the one on EBay. Sells in the US astro shops for $25 plus about $30 postage.
Get it now i think

Carl

[erick]

Yes I did and it probably might suffer some mirror flop, but not much is my past experience. Unfortunately cloud stopped me from testing on a real star that night.

[erick]

I think I bought from ebay - straight from Hubble Optics and from Hong Kong. Easy.

[mill]

I just bought one from Hubble Optics, see how long it takes to come in.

[mikerr]

Just got mine from Hubble Optics. Will try it out over Christmas!

Michael

[toc]

I got one via a cloudynights advert - works well for the C8, but i cant use it with my 12 inch meade - i dont have enough room to bring it into focus :(

[Merlin66]

Tim,
You can use a secondary mirror/ ex-star diagonal etc to double the light path...set the torch alongside the scope and the mirror as far as possible.....

[casstony]

Now that's a good idea which I hadn't thought of.

The best thing about the artificial star is I can collimate on a calm overcast day at high power instead of mucking around at night. While ok collimation is quick and easy, I find it takes a little patience/fiddling to get the in focus diffraction ring even all the way around and my night time seeing is never good enough to do this anyway.

[mikerr]

Tim, do you mean that you can't get the artificial star far enough away from the 12 inch Mead? How far away does it need to be? How far did you have it from the C8?

Merlin, if the light path is folded, will it still remain a point source like a real star?
Maybe folding the path would be a way of pointing the reflector scopes up at an angle to check the effect of Mirror Flop, on the collimation process.

Michael

[Merlin66]

yes, The artificial star is unaffected....just gives you the distance you may need.

To check the maximum mirror "flop" you just need to measure the focuser in/ out "slop" - the "flop" can never exceed the "slop"
I use a CCD camera to view the focused image from each direction and just measure the "slop" in pixel movement...for my C9.25 the focus "slop" was only 6 pixels!!

[toc]

I will need a football field :) I tried using a few diagnals, but I need to extend the eyepiece about 1/2 a meter before I can get it to focus.

[toc]

I could easily get it to focus with the C8 by having the scope at one end of my hall, and the torch in my daughters bedroom - a distance of about 13 or 14 metres. The Meade would seem to need at least 20.