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hubble-optics
Vendor- Hubble Optics

Reged: 05/02/07

Loc: Hong Kong, US

5-star Artificial Star
#3042836 - 04/14/09 05:52 AM Attachment (172 downloads)

The star test is the ultimate method for the collimation and quality verification of your telescopes. Sadly, a real star is not always available, and you really may not want to spend your precious observation time doing collimation and verification even when it is available. Of course, you will also need a good tracking system for doing star test with the moving real star. After all the troubles, due to the turbulence, the real star may not even reveal the true quality of your telescopes.

An artificial star will provide you an excellent alternative mean to do the star test anytime and anywhere you want, without all the drawbacks of the real stars. However, the problem with artificial star is that you really need different size of artificial stars for different telescopes of different apertures with different F/#, and even for the same telescopes but at different distances, and under different lighting environment.

Our five-star artificial star is a perfect solution to this problem. It has 6 bright white LEDs with 5 precision pinholes (50/100/150/200/250 microns). It will enable you to test practically all the telescopes of different apertures with different F/#, from any reasonable distances needed!

-You can instantly find out which star is best for your particular telescope at that particular distance under that particular lighting environment.

-You can adjust the brightness of the stars by twisting the LED head.

-You can mask out any 4 stars with a provided magnetic mask.

Please make sure the cleanness of the mask, and use it only when needed to prevent the blockage of the pinholes.

To purchase a 5-star Artificial Star at $14.95:

http://hubbleoptics.com/artificial-stars.html

or

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=200331472146

Thank you,
Tong

Hubble Optics

Edited by hubble-optics (04/15/09 09:40 PM)

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skyjim
Carpal Tunnel

Reged: 01/13/07

Loc: Long Island, NY

Re: 5-star Artificial Star new

new

[Re: hubble-optics]
#3043091 - 04/14/09 09:36 AM

Hi Tong, will you be at Neaf this weekend maybe??? If not I dont use ebay, do you have a sight or phone # I can contact your company at?
Jim

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Daniel Mounsey
Vendor - Celestron

Reged: 06/12/02

Re: 5-star Artificial Star new

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[Re: skyjim]
#3043184 - 04/14/09 10:44 AM

Sounds like a good price too.

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jrcrilly
Refractor wienie no more

Reged: 04/30/03

Loc: NE Ohio

Re: 5-star Artificial Star new

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[Re: Daniel Mounsey]
#3043217 - 04/14/09 11:02 AM

Quote:

Sounds like a good price too.

Yup. For $20 I'll give it a shot (should be better than the Christmas tree ornament I spent a few hours staring at last weekend at 600X).

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hubble-optics
Vendor- Hubble Optics

Reged: 05/02/07

Loc: Hong Kong, US

Re: 5-star Artificial Star new

new

[Re: skyjim]
#3043264 - 04/14/09 11:32 AM

Hi Jim,

I am sorry that we will not be in NEAF. However, we have just added a page in our website where you can order it directly:

http://hubbleoptics.com/artificial-stars.html

You can contact us at info@hubble-optics.com

Thank you and best regards,
Tong

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snowdragonusa
Pooh-Bah

Reged: 09/04/07

Loc: Denver, CO

Re: 5-star Artificial Star new

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[Re: jrcrilly]
#3044558 - 04/15/09 12:10 AM

Yup, me too. I just ordered one. For $20 shipped I'll give it a go. Our Colorado skies make it difficult to get a good collimation most evenings.

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hubble-optics
Vendor- Hubble Optics

Reged: 05/02/07

Loc: Hong Kong, US

Re: 5-star Artificial Star new

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[Re: snowdragonusa]
#3044888 - 04/15/09 08:04 AM

Thank you all for the support. BTW, we have just added a note in our website to indicate the products will be shipped in about week. Sorry for the late notice and the waiting time.

Tong

Hubble Optics

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Sarkikos
Postmaster

Reged: 12/18/07

Loc: Suburban Maryland, USA

Re: 5-star Artificial Star new

new

[Re: hubble-optics]
#3045102 - 04/15/09 10:46 AM

I just pulled the trigger on this gizmo. I've always heard that to properly collimate your optics or to test your optics, you should do a star test. The catch-22 is that to do a proper star test you need close-to-perfect seeing. Yeah, like that's going to happen on a regular basis where I live. So now we'll see if I have a long enough run in my house to perform the test. I guess I could rig up a system of mirrors to fold-up the rays. Why not? We do it all the time in our Newts and Cats and Binos.

Mike

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Sarkikos
Postmaster

Reged: 12/18/07

Loc: Suburban Maryland, USA

Re: 5-star Artificial Star new

new

[Re: Sarkikos]
#3045130 - 04/15/09 11:05 AM

Tong's website brought up another positive point about using an artificial star for collimating. If you use a real star, you really need to track it. Otherwise you'll be pulling your hair out glancing at the out-of-focus star at high power, jumping back to adjust the screws on back of the mirror, nudging the star back into view, jumping back to the screws, nudging the star back ... Not something I would want to do. I suppose you could teach a friend or your wife how to adjust collimation screws or interpret an airy disk. Also, something I may not want to do. Forgetaboutit. Some things are better done alone.

An idea: If you set up the artificial star in your house right beside your scope, and point them both at a mirror at the farthest distance away at the other end of your house, you would be able to set it up in half the distance and could just reach over to select a different size pinhole or adjust the brightness as needed. It may even be possible to insert the artificial star in your optical or laser finder mount attached to your scope tube, or via a 1/4-20 screw to your scope's ring, and adjust its position easier from there.

Mike

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jsiska
professor emeritus

Reged: 07/12/06

Loc: NW Ohio

Re: 5-star Artificial Star new

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[Re: Sarkikos]
#3045164 - 04/15/09 11:30 AM

Interesing. Can you provide a little more detail on how to determine which of the 5 precision pinholes (50/100/150/200/250 microns) are to be selected based on the telescopes of different apertures with different F/#, and also with usage of different reasonable distances.

Thanks,
Jim

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Sarkikos
Postmaster

Reged: 12/18/07

Loc: Suburban Maryland, USA

Re: 5-star Artificial Star new

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[Re: jsiska]
#3045182 - 04/15/09 11:35 AM

Jim,

I'm at a loss as to those details, myself. This sounds like a good question for Mr. Tong.

Mike

For Mr. Tong,

We'd appreciate a little help in this regard, Mr. Tong.

Thanks,
Mike

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hubble-optics
Vendor- Hubble Optics

Reged: 05/02/07

Loc: Hong Kong, US

Re: 5-star Artificial Star new

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[Re: Sarkikos]
#3045304 - 04/15/09 12:50 PM

Dick Suiter’s Star Testing Astronomical Telescope has a full explanation on this topic, in particular, the section 5.2.1, Distance of Artificial Sources and 5.2.2, Diameter of Artificial Sources.

Here is a direct quote from page 86:

“We must carefully select a pinhole size in the artificial source so that it is smaller than the resolution of the instrument. On the other hand, it must be large enough to allow sufficient illumination to fill a defocused image with light. To calculate such a diameter, we extend the Airy disk radius to the distance of the pinhole”

Table 5-2 gives out the min telescope to artificial star distance, and Table 5-3 gives out the max diameter of artificial stars for different telescope (Apertures, F/#).

As for the 5-star artificial star, the rule to choose the best star is very simple; for whatever scope at whatever distance, you should always choose the smallest possible star, but which still give you the clear defocus image.

Best regards,
Tong

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snowdragonusa
Pooh-Bah

Reged: 09/04/07

Loc: Denver, CO

Re: 5-star Artificial Star new

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[Re: Sarkikos]
#3045735 - 04/15/09 05:29 PM

Quote:

An idea: If you set up the artificial star in your house right beside your scope, and point them both at a mirror at the farthest distance away at the other end of your house, you would be able to set it up in half the distance and could just reach over to select a different size pinhole or adjust the brightness as needed. It may even be possible to insert the artificial star in your optical or laser finder mount attached to your scope tube, or via a 1/4-20 screw to your scope's ring, and adjust its position easier from there.

Hmmm, an interesting idea. However, wouldn't you be be collimating any surface errors of the mirror? Similar to collimating with or without your diagonal?

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Sarkikos
Postmaster

Reged: 12/18/07

Loc: Suburban Maryland, USA

Re: 5-star Artificial Star new

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[Re: hubble-optics]
#3046090 - 04/15/09 08:39 PM

Tong,

"Dick Suiter’s Star Testing Astronomical Telescope"

Oh yes, I'd like to own a copy of this guide and be able to consult it at my leisure, but with it being apparently out of print, and used copies selling for $127, I think for the immediate future I'll be limited to little snippets such as you have given graciously here.

"To calculate such a diameter, we extend the Airy disk radius to the distance of the pinhole”

Whoa! English is my native language and a know something about astronomy and optics, but ... huh?

"As for the 5-star artificial star, the rule to choose the best star is very simple; for whatever scope at whatever distance, you should always choose the smallest possible star, but which still give you the clear defocus image."

I like your precedure better, Tong. Much simpler and easier to understand.

Thanks for the help,
Mike

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Sarkikos
Postmaster

Reged: 12/18/07

Loc: Suburban Maryland, USA

Re: 5-star Artificial Star new

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[Re: Sarkikos]
#3046116 - 04/15/09 09:03 PM

Adam,

"Hmmm, an interesting idea. However, wouldn't you be be collimating any surface errors of the mirror? Similar to collimating with or without your diagonal?"

Hey, I'm new to any kind of collimating beyond peephole caps, cheshires, sight tubes and laser collimaters. (And I've stopped using the lasers. They give a false sense of perfection, as I see it.) I am still trying to figure all this out. I've never done a "star test." (Why waste a rare night of good seeing on collimating? I want to observe stuff.) I collimate with the diagonal. How and why would you do it any other way?

Seriously though, I might be wrong, but I think that surface errors of a flat mirror wouldn't really affect the collimation. Maybe I'll use an old diagonal that's about 25 years old and is up in the attic. I could mount it on a tripod. Hey, unless I do something to fold the light path, I might not have enough room in my house to do the test! I don't have a back yard I can utilize for such things. And I don't want to wait until I'm out in the field to do the artificial star collimation, though I guess that is possible if I travel to a dark site.

Mike

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hubble-optics
Vendor- Hubble Optics

Reged: 05/02/07

Loc: Hong Kong, US

Re: 5-star Artificial Star new

new

[Re: Sarkikos]
#3046152 - 04/15/09 09:28 PM

The HRS's must have Star Testing Astronomical Telescopes, Second Edition, is ready to ship now! Better yet, it is still priced at special pre-publication offer at $29.95, at least for now!

http://www.willbell.com/TM/tm5.htm

Thanks,
Tong

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Sarkikos
Postmaster

Reged: 12/18/07

Loc: Suburban Maryland, USA

Re: 5-star Artificial Star new

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[Re: hubble-optics]
#3046872 - 04/16/09 10:34 AM

Hi Tong,

Thank you much for the heads up about the Star Testing book. Yes, ordering it pre-publication is probably the only way to get it at a reasonable price. I'm still awaiting the next publication announcement for Rukl's Atlas of the Moon.

Thanks,
Mike

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Sarkikos
Postmaster

Reged: 12/18/07

Loc: Suburban Maryland, USA

Re: 5-star Artificial Star new

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[Re: Sarkikos]
#3046903 - 04/16/09 10:54 AM

I just ordered Star Testing Astronomical Telescopes, Second Edition from willbell.com. I also picked up a copy of Bright Star Atlas so I can take it out with my binos and grab-n-go scopes.

Thanks again, Tong!

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hubble-optics
Vendor- Hubble Optics

Reged: 05/02/07

Loc: Hong Kong, US

Re: 5-star Artificial Star new

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[Re: Sarkikos]
#3048147 - 04/16/09 11:33 PM

Mike,

You are welcome! BTW, here are some very useful online helps on star test:

http://perso.club-internet.fr/legault/collim.html
http://www.astunit.com/tutorials/startest.htm

Some very helpful star test examples, and an extremely useful star test simulator to get familiar with star test
http://aberrator.astronomy.net

Best regards,
Tong

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Sarkikos
Postmaster

Reged: 12/18/07

Loc: Suburban Maryland, USA

Re: 5-star Artificial Star new

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[Re: hubble-optics]
#3048671 - 04/17/09 08:57 AM

Tong,

I'll check them out. I've used telescopes since the early '70's, but I'm still a newbie when it comes to star testing, so I need all the help I can get.

Thanks,
Mike

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