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Value of Hubble Optics Artificial Star?

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#1 mitaccio

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Posted 14 January 2013 - 05:43 PM

From my yard (only observation location) I don't have a view of Polaris and rarely have seeing above 5/10. Doing a star test for my collimation is all but impossible. Then I hear about this Artificial Star from Hubble Optics. The price is great, but it seems too simple. Can I reasonably expect to get a GREAT collimation for my 8SE using this device?

#2 Bob Griffiths

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Posted 15 January 2013 - 08:18 AM

I own a Pico Star Artificial star...

I use it for all my scopes EXCEPT my SCTS...

Simple reason is that the OTA on a SCT has to be pointed upward to check and adjust your collimation so that the weight of the mirror holds it in place...

The only way to do this would require that the Artificial star to be positioned on top of a telephone phone or on a window ledge of a window on the 3rd or 4th floor of a building...and the scope set up about 100 feet from the pole or building..

The Pico star is a nice (although not cheap) piece of gear

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#3 chemist

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Posted 15 January 2013 - 02:21 PM

While Bob G. is technically correct regarding the "mirror flop" associated with SCTs, I have used the Hubble Optics artificial star to collimate my 6SE with good success. Admittedly, you may have to "tweak" the collimation using a real star test, but the Hubble will get you pretty darn close.

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#4 mtw4518

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Posted 15 January 2013 - 07:26 PM

While Bob G. is technically correct regarding the "mirror flop" associated with SCTs, I have used the Hubble Optics artificial star to collimate my 6SE with good success. Admittedly, you may have to "tweak" the collimation using a real star test, but the Hubble will get you pretty darn close.

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When you use the artificial star, what distance do you use from the scope?

#5 Tel

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Posted 16 January 2013 - 04:38 AM

Hi mtw4518,

Assuming our UK Astro Engineering produced "Picostar", (artificial star collimator), is essentially the same as the Hubble Optics unit, (which I'm sure it is), the minimum distance for an 8" (200mm) 'scope appears to be ca. 15 metres: ( ca. 50 ft.). (See attached screen shot)

Also, perhaps you might find the attached link to Astro Engineering's You Tube video regarding their instrument's workings of some interest.

http://www.youtube.c...h?v=yioruTXsjco

Hoping this helps,

Best regards,
Tel

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#6 Tel

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Posted 16 January 2013 - 05:33 AM

Just a footnote to the above:

Looking at that AE video, it makes me wonder somewhat, whether merely stopping-down a small, simple flash light might not be almost, if not as good, as one of these "Picostar" units ! :idea:

Would one actually be able to detect a significant difference in the image quality between the use of either to collimate ?

Worth an experiment or two anyone ? :idea:

Best regards,
Tel

#7 Midnight Dan

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Posted 16 January 2013 - 07:22 AM

Hi Tel:

I tried this once with an LED flashlight. I covered it with aluminum foil and poked a pinhole in the foil. Worked ok, but not as well as a commercially made model.

The issue seems to be the size and roundness of the hole that the light goes through. You want it to be very tiny and very round. The one I ended up buying had a laser cut hole of I think 100 microns in size. My pinhole was much larger and the edges were quite ragged because the foil had just been pushed out of the way by the pin, not drilled cleanly.

The result was a star image that was somewhat spikey looking which interfered with getting a good collimation image.

-Dan

#8 Bob Griffiths

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Posted 16 January 2013 - 08:56 AM

You can close by just using a small Christmas tree bulb with a flashlight shinning on it off at an angle...then setting the scope up 60 to 70 foot away I I have done this with some of my scopes (prior to buying the picostar) set the Christmas tree bulb up inside one of my garages and the scope in my other garage .....

Easiest way is to use a glass insulator on top of a telephone pole on a nice sunny day..

If you got the money...there is a $500.00 laser collimating device that works for SCTS.. made by Hotech or something like that...

Bob G.
Bob G.

#9 WaterMaster

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Posted 16 January 2013 - 10:20 AM

I've used the christmas tree ornament trick outside with the sun as the 'illumination source' to collimate my dob. It was difficult as the background was pretty bright and made it tough to clearly see the rings, but it worked. :shrug:

You can have the best optics on the planet, but if they're not properly collimated...

If you can fit it in your budget good collimation tools (artificial stars, lasers, etc.) will pay you back with great views. :ubetcha:

#10 chemist

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Posted 16 January 2013 - 11:42 AM

Just for the record, I setup the Hubble about 150ft away from the scope and sight in on the smallest of the five pinholes in the mask using a 6mm EP on my 6SE (6mm w/2x Barlow on my 80A). I do this about 30min after sunset which offers a good compromise between dark background and enough light to still see what I'm doing. At sharp focus I see an Airy disk and 2 or 3 diffraction rings.

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#11 kkokkolis

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Posted 16 January 2013 - 12:42 PM

I have one too and it is very nice. But I didn't use it that much because I thought that a very long distance is needed and in urban enviroment this means I should put it on somebode else's property. But if 12m is enough as Tel says, then I can do it indoors.
The produced stars are perfect and you get various diameters (emulated mags that is) and seeing can't affect you at 12-15m, with the exception of fog in London perhaps. ;)

#12 Tel

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Posted 17 January 2013 - 05:32 AM

Hi Tel:

I tried this once with an LED flashlight. I covered it with aluminum foil and poked a pinhole in the foil. Worked ok, but not as well as a commercially made model.

The issue seems to be the size and roundness of the hole that the light goes through. You want it to be very tiny and very round. The one I ended up buying had a laser cut hole of I think 100 microns in size. My pinhole was much larger and the edges were quite ragged because the foil had just been pushed out of the way by the pin, not drilled cleanly.

The result was a star image that was somewhat spikey looking which interfered with getting a good collimation image.

-Dan


Many thanks Dan, it was just a thought that having looked at the video, something "cheap and cheerful" might just do the job well enough; given all the parameters/conditions likely to adversely affect one's attempts at collimation. After all, the Hubble artificial star's price, (certainly to you guys in the States), is, as we say over here, "Cheap as chips" compared with Astro Engineering's UK price for their version, of ca. £66 (ca.$100) :4

Overall though, I think they are a good idea, although not too easy to employ given the necessity to position them so far from many mid-range 'scopes, thus precluding use from apartment blocks or small backyards ! :idea:

BTW. I wish you all success in your observatory planning and I hope all goes well with the authorities. I'm sure it will ! :waytogo:

Best regards,
Tel

#13 BSJ

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Posted 21 January 2013 - 03:23 PM

I have one too and it is very nice. But I didn't use it that much because I thought that a very long distance is needed and in urban enviroment this means I should put it on somebode else's property. But if 12m is enough as Tel says, then I can do it indoors.
The produced stars are perfect and you get various diameters (emulated mags that is) and seeing can't affect you at 12-15m, with the exception of fog in London perhaps. ;)


Can your scope focus that close? If not, you'll need more distance.






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