artificial stars?

[h0ughy]

looking at gettin an artificial star for use in collimation, have looked at this one (http://www.hubbleoptics.com/artificial-stars.html) - is it worth it?:shrug:

[redbeard]

Hi David,

A friend of mine has one and that's how he collimated his scope. (Meade 10" LX200GPS). He was very happy with the results and his images back that up. He put it in a neighbours tree down the road from his house.

I also have one but have not tested it as yet.

You do need some distance to use it, 35 meters ish depending on scope parameters.

I did some reading on the web myself and like all things there are many sides to a topic. Some mentioned that you need a real star, others not.

Good luck.

Cheers,

Damien.

[MrB]

Hmmm looks ok.
I was just going to make one with a CREE LED torch and some aluminium tape with pin pricks in it, but for that price it might not be worth all the effort trying to get a nice clean right-size pin prick.

[alistairsam]

I bought one a lil while ago but haven't tried it as yet.
quality wasn't great, but it is as advertised. so worth a try.

[h0ughy]

thanks for the input. might have to follow up a review

[troypiggo]

I've got that exact one. I thought it was ok, but when I compared it to peter_4059's homemade one, it pales in comparison of brightness. His was much brighter and easier to get the airy disk.

[MrB]

There we go, that's what we needed to hear.
Back to plan A for me ;)

[Astro_Bot]

I have that exact one and have used it several times to collimate an SCT. It works fine, even using the dimmest LED. I did make up a better magnetic mask from an old fridge magnet as the supplied one, while OK, was fiddly to adjust and would fall off if touched.

Assuming it's used at night, I can't imagine requiring anything brighter. I use mine at a range of 22m indoors, even with a couple of lounge lamps still on (but not anywhere near the field of view). Outside, I'd imagine it'd be good at >100m using the brightest LED.

Leaving a dim lamp on can be helpful as it gives some "artificial skyglow" that outlines the field of view and makes centring the diffraction rings easier.

I've checked collimation results outside with Sirius and found the collimation I did to be spot on.

Edit: I keep saying "brightest LED" or "dimmest LED" but, actually, all the LEDs are the same and it's the size of the hole that changes, thus letting through more (or less) light.

[Astro_Bot]

I looked into that, too, and decided that I couldn't get clean enough holes anywhere near small enough. Laser drilled holes would be great but bloody expensive! I think the CREE LED would be overkill unless you want daytime use.

[h0ughy]

but it worked? i am useless making things but the price seems right on this?

[Astro_Bot]

Just had a thought: Did you check the pinholes were aligned in front of the LEDs? I took mine apart and, when reassembling, made sure that was the case. I expect it would be dimmer if the LEDs were out of alignment between the holes.

[Steffen]

I've got the Hubble one, too, and find it works well. The magnetic mask is rather useless as it doesn't stay in place but that's not a big issue. The torch itself seems to be a run-of-the-mill LED torch but the pinhole screen is well made, the diffraction patterns on mine look flawless.

Cheers
Steffen.

[MrB]

I had a feeling that may be the case, but I recall reading years ago (when I used to be on the ATM mailing list) about people doing this successfully to make artificial stars to test optical figure so thought I'd give it a go.

I was only going to use a CREE because I have a stack of them not being used, they do have brightness adjustment so no worries there.
But after your positive review, I'm now thinking about the Hubble again.
Yo-yo :lol:

[ourkind]

Just bought it myself ahhh the joys of impulse buying :)

Thanks for the vote of confidence astro-bot :thumbsup:

[Astro_Bot]

Well, it lives up to my expectations, so hopefully it meets yours, too. For $25 delivered you can't really go wrong, though.


Add a couple of bottles of wine while watching late night TV, and that is how I came to own a complete set of Anthony Robbins motivational CDs. :screwy:

[ourkind]

My thoughts exactly :thumbsup:



Oh no no no we'll need to start another thread for that one :lol: I've been there and done that, AR in person at the Entertainment Centre :screwy: my wife dragged me through it (I refused to walk the hot coals) The mounts and scopes I could've bought with the money spent on those seminars :question:

[AndrewJ]

You need acupuncture needles.;)
I made up a "drill press" using a hypodermic needle glued into a bit of wood.
Feed the Acupuncture needle down the middle and you can position it over some alfoil and make precision round holes in a very slow and steady/controlled manner.
Put an ultrabright white LED behind it and you can see it easily.

Andrew

[BlackWidow]

Hi Dave. I have one of these and the work fantastic. You have a choice of stars so you can pic the best for your needs to see the rings. I put mine on a griped in the neibours driveway and have my scope in my driveway.. I can even do it during the day.. For the price and the fact that it will work, I could not be bothered with spending time making one that may or may not work..

Just my opinion. :thumbsup:

[troypiggo]

Sorry, took a while to reply.

Yes, it works. But not as well (IMO) as the homemade one of Peter's.

I was using it on both 2350mm FL SCT and 1200mm FL Newt. Had to place the artificial stars quite a long way away due to min focus distances - maybe 60-100m? At that distance I was having to use the biggest hole in the art star for my eyes to pick up airy disk etc.

So in short, yes it works. And I won't be making my own one. But if I didn't have one, I'd prefer to give Peter a carton of beer and have him make me one :D

[multiweb]

I used the astrozap (http://www.optcorp.com/product.aspx?pid=10823)for years. Does the job. Not cheap but one of those things you buy once.

[tlgerdes]

I have made a couple, using computer fibre optic cables, terminated 50 micron fibre.

One was a single light point, 1x F/O cable, 2x 1.5v batteries and an 2000mcd 5mm white LED, 3" of black electrical tape and 3"x6" jiffy box

The other 9 light points on a 1.2mx0.6m board.

The large one is great for adjusting coma correctors, field flatteners etc as you can take an image and look at FOV without moving the scope back and forth.

[alistairsam]

Hi,
can anyone post some links on how exactly you adjust collimation, coma correctors and what you should look for? I'm guessing you defocus and check if the secondary is centered? but is that about it?

[tlgerdes]

I was doing it by taking a photo, evaluating the picture, making an adjustment, re-iterating. Work in ½mm increments.

Mind you, that only works if you have an infinitely adjustable spacer :question:

[coldlegs]

Would some optics genius please invent one that can either hang off the end of the scope or within 5m. I just cant get 35-40m.
Cheers
Stephen

[PRejto]

It's been done! Anyone have any experience with this?

http://www.hotechusa.com/category-s/23.htm

[Astro_Bot]

At around $500 delivered, I'm not sure that's an experience I want. But if I ever win the lottery .....

You know you can collimate using a real star as long as seeing is reasonable? With practice, it can be done in ~5 minutes.

I first started with the Hubble Optics artificial star until I had practiced and knew what I was doing, and figured out how well collimation held, but don't use it that often anymore since I can do it "on the night" with equal ease.

The artificial star is useful for testing mechanical/optical alignment in the comfort of your own home - something that's more difficult to do in the field - and that's where I've used it most.

[originaltrilogy]

Yes please, I did buy one of these hubble stars, but they have no instructions. I would like to use with my C11 EdgeHD if there are instructions for usage.

[LewisM]

Buy a good refractor. Problem solved.

OK, I'll scurry away now :)

[Poita]

If you have a refractor that gives as good a photgraphic image of Jupiter and Saturn as a C11, then no problem :)

An easy guide is here: http://www.starrynights.us/Articles/Collimation.htm

It literally takes 5 mins to collimate a cat.

and here
http://www.astromart.com/articles/article.asp?article_id=548