Artificial Star using Christmas tree ornament ?
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Re: Artificial Star using Christmas tree ornament ?
And sorry for the misinformation.
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Re: Artificial Star using Christmas tree ornament ?
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Re: Artificial Star using Christmas tree ornament ?
Lady Fraktor wrote: ↑Mon Dec 21, 2020 6:49 pmIf you have figured out the distance you need to star test, shorten that distance for collimating to 70% of the distance and it will work fine.UlteriorModem wrote: ↑Mon Dec 21, 2020 3:15 pm I bought an arti star. It's basically a flash light with a cover and tiny pin holes in it.
Found out I could not use it as there was no where in my yard far enough away. I would have to put it about halfway out in my neighbor's yard... that aint gonna work.
Lets see. The average star I use to test is a couple of thousand light years away sooo lets see 70% of that is ... well still past my neighbor's yard
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Re: Artificial Star using Christmas tree ornament ?
ArseUlteriorModem wrote: ↑Tue Dec 22, 2020 3:38 am Lets see. The average star I use to test is a couple of thousand light years away sooo lets see 70% of that is ... well still past my neighbor's yard
USING A ARTIFICIAL STAR FOR COLLIMATION OR STAR TESTING:
For an artificial star, the apparent angular diameter of a pinhole style uniform opening is:
d = 206265(P/D)
Where d is the angular diameter in arc-seconds, and P is the opening size of the pinhole (mm) and D is the distance (mm) to the “star”.
To FULLY test reliably within the resolution of the scope, you need this distance to match the resolving power of the scope. (if you want to evaluate things like aberrations (Spherical, Astigmatism,
While one CAN use many criteria, it is likely best to use Dawes’s limit for the scope to allow the Rayleigh limit (which is slightly larger) to be satisfied. On average, R ~ 115.9/A; where A is the
So, 115.9/A ~ 205265P/D, which rearranges to:
D = ~ 206265PA/115.9 – so using mm, that means that D ~ 1780PA.
For a 4” (102mm) scope, and a 100um (0.1mm) pinhole for the artificial star:
D = 1780* 0.1*102 = 18156mm, or 18.16m – this is about 55 feet. To use a 50um pinhole, you would be at ~27.5 feet (9m) in this case.
For a general collimation only evaluation, you can safely use 70-80% of this value or even about 20-24 feet if necessary. That is the CLOSEST reliable test distance.
Testing for proper collimation and especially optical quality is only possible if the “pinhole” for the illumination source is very well made – the more ideal to perfect hole, the better the results.
Illuminants can be anything, like LEDs, flashlights, candles and bulbs, just make sure they are pre-diffused to allow uniform illumination of the source.
This is the minimum pinhole distance for diffraction-limited collimation.
Tables 1 and 2 give the distances in more convenient feet and meters for popular apertures in inches and centimetres and pinhole sizes in microns
TABLE 1: https://www.dropbox.com/s/753wqpzvrspwd ... s.jpg?dl=0
TABLE 2: https://www.dropbox.com/s/i4wio333h0zlh ... s.jpg?dl=0
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Re: Artificial Star using Christmas tree ornament ?
See Far Sticks: Elita 103/1575, AOM FLT 105/1000, Bresser 127/1200 BV, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS 100/1000, Vixen SD115s/885
EQ: TAL MT-1, Vixen SXP, SXP2, AXJ, AXD
Az/Alt: AYO Digi II, Stellarvue M2C, Argo Navis encoders on both
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Re: Artificial Star using Christmas tree ornament ?
If the "pinhole" was 60 mm (Christmas tree ornament diameter) and lens diameter was 102 mm:
D = 206265PA/115.9 = 206265 * 60 * 102 / 115.9 = 10891646 mm = 10.8 km
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Re: Artificial Star using Christmas tree ornament ?
The idea is to consider the ball (bearing ball, Christmas tree ornament) as a convex spherical mirror.
I found out that the focal length of a spherical mirror is half of its radius.
The rest is still under study. :-D
Senior Embedded SW Designer
Telescope: OrionOptics XV12, Mount: CEM120, Tri-pier 360 and alternative dobson mount.
Grab 'n go: Omegon AC 102/660 on AZ-3 mount
Eyepieces: 26 mm Omegon SWAN 70°, 15 mm TV Plössl, 12.5 mm Baader Morpheus, 10 mm TV Delos, 6 mm Baader Classic Ortho, 5 mm TV DeLite, 4 mm and 3 mm TV Radians
Cameras: ZWO ASI 294MM Pro, Omegon veLOX 178C
OAG: TS-Optics TSOAG09, ZWO EFW 7 x 36 mm, ZWO filter sets: LRGB and Ha/OIII/SII
Explore Scientific HR 2" coma corrector, Meade x3 1.25" Barlow, TV PowerMate 4x 2"
Some filters (#80A, ND-96, ND-09, Astronomik UHC)
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LAT 61° 28' 10.9" N, Bortle 5
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Re: Artificial Star using Christmas tree ornament ?
Here the focal length if R/2. Clear for "earthly goods" but a bit fifferent for far away big objects.
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Re: Artificial Star using Christmas tree ornament ?
1/do + 1/di = 1/f, where do is object distance and di is image distance (in this case behind the mirror).
m = hi/ho = -di/do, where m is magnification, ho is height of the object and hi is height of the image.
distance behind the mirror is considered negative (always the case with convex mirror)
So 10 mm flashlight 10 meters away gives an image on a 100 mm Christmas tree ornament:
f = 25mm, 1/di = 1/25 - 1/10000, di = 25,062
di/do = 0,002506
hi = (di/do) * ho = 0.025 = 25 um
Please correct if I'm wrong.
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Re: Artificial Star using Christmas tree ornament ?
JT
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Re: Artificial Star using Christmas tree ornament ?
And I'm learning too in the process.
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Telescope: OrionOptics XV12, Mount: CEM120, Tri-pier 360 and alternative dobson mount.
Grab 'n go: Omegon AC 102/660 on AZ-3 mount
Eyepieces: 26 mm Omegon SWAN 70°, 15 mm TV Plössl, 12.5 mm Baader Morpheus, 10 mm TV Delos, 6 mm Baader Classic Ortho, 5 mm TV DeLite, 4 mm and 3 mm TV Radians
Cameras: ZWO ASI 294MM Pro, Omegon veLOX 178C
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Some filters (#80A, ND-96, ND-09, Astronomik UHC)
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LAT 61° 28' 10.9" N, Bortle 5
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Re: Artificial Star using Christmas tree ornament ?
BTW, about what size is your bearing ball?
Senior Embedded SW Designer
Telescope: OrionOptics XV12, Mount: CEM120, Tri-pier 360 and alternative dobson mount.
Grab 'n go: Omegon AC 102/660 on AZ-3 mount
Eyepieces: 26 mm Omegon SWAN 70°, 15 mm TV Plössl, 12.5 mm Baader Morpheus, 10 mm TV Delos, 6 mm Baader Classic Ortho, 5 mm TV DeLite, 4 mm and 3 mm TV Radians
Cameras: ZWO ASI 294MM Pro, Omegon veLOX 178C
OAG: TS-Optics TSOAG09, ZWO EFW 7 x 36 mm, ZWO filter sets: LRGB and Ha/OIII/SII
Explore Scientific HR 2" coma corrector, Meade x3 1.25" Barlow, TV PowerMate 4x 2"
Some filters (#80A, ND-96, ND-09, Astronomik UHC)
Laptop: Acer Enduro Urban N3 semi-rugged, Windows 11
LAT 61° 28' 10.9" N, Bortle 5
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Re: Artificial Star using Christmas tree ornament ?
14mm
∞ AP Scopes: #1: TPO 6" f/9 RC #2: ES 102 f/7 APO #3: ES 80mm f/6 APO
∞ G&G Scopes: #1: Meade 102mm f/7.8 #2: Bresser 102mm f/4.5
∞ Guide Scopes: 70 & 80mm fracs -- The El Cheapo Bros.
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Re: Artificial Star using Christmas tree ornament ?
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Re: Artificial Star using Christmas tree ornament ?
In konza's signature it says "Scopes: ES102
Senior Embedded SW Designer
Telescope: OrionOptics XV12, Mount: CEM120, Tri-pier 360 and alternative dobson mount.
Grab 'n go: Omegon AC 102/660 on AZ-3 mount
Eyepieces: 26 mm Omegon SWAN 70°, 15 mm TV Plössl, 12.5 mm Baader Morpheus, 10 mm TV Delos, 6 mm Baader Classic Ortho, 5 mm TV DeLite, 4 mm and 3 mm TV Radians
Cameras: ZWO ASI 294MM Pro, Omegon veLOX 178C
OAG: TS-Optics TSOAG09, ZWO EFW 7 x 36 mm, ZWO filter sets: LRGB and Ha/OIII/SII
Explore Scientific HR 2" coma corrector, Meade x3 1.25" Barlow, TV PowerMate 4x 2"
Some filters (#80A, ND-96, ND-09, Astronomik UHC)
Laptop: Acer Enduro Urban N3 semi-rugged, Windows 11
LAT 61° 28' 10.9" N, Bortle 5
I don't suffer from insanity. I'm enjoying every minute of it.
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Re: Artificial Star using Christmas tree ornament ?
This myth is feasible! :smile:
Senior Embedded SW Designer
Telescope: OrionOptics XV12, Mount: CEM120, Tri-pier 360 and alternative dobson mount.
Grab 'n go: Omegon AC 102/660 on AZ-3 mount
Eyepieces: 26 mm Omegon SWAN 70°, 15 mm TV Plössl, 12.5 mm Baader Morpheus, 10 mm TV Delos, 6 mm Baader Classic Ortho, 5 mm TV DeLite, 4 mm and 3 mm TV Radians
Cameras: ZWO ASI 294MM Pro, Omegon veLOX 178C
OAG: TS-Optics TSOAG09, ZWO EFW 7 x 36 mm, ZWO filter sets: LRGB and Ha/OIII/SII
Explore Scientific HR 2" coma corrector, Meade x3 1.25" Barlow, TV PowerMate 4x 2"
Some filters (#80A, ND-96, ND-09, Astronomik UHC)
Laptop: Acer Enduro Urban N3 semi-rugged, Windows 11
LAT 61° 28' 10.9" N, Bortle 5
I don't suffer from insanity. I'm enjoying every minute of it.
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Re: Artificial Star using Christmas tree ornament ?
The ornament diameter was 60 mm and the distance was the same 1.4 m.
Senior Embedded SW Designer
Telescope: OrionOptics XV12, Mount: CEM120, Tri-pier 360 and alternative dobson mount.
Grab 'n go: Omegon AC 102/660 on AZ-3 mount
Eyepieces: 26 mm Omegon SWAN 70°, 15 mm TV Plössl, 12.5 mm Baader Morpheus, 10 mm TV Delos, 6 mm Baader Classic Ortho, 5 mm TV DeLite, 4 mm and 3 mm TV Radians
Cameras: ZWO ASI 294MM Pro, Omegon veLOX 178C
OAG: TS-Optics TSOAG09, ZWO EFW 7 x 36 mm, ZWO filter sets: LRGB and Ha/OIII/SII
Explore Scientific HR 2" coma corrector, Meade x3 1.25" Barlow, TV PowerMate 4x 2"
Some filters (#80A, ND-96, ND-09, Astronomik UHC)
Laptop: Acer Enduro Urban N3 semi-rugged, Windows 11
LAT 61° 28' 10.9" N, Bortle 5
I don't suffer from insanity. I'm enjoying every minute of it.
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Re: Artificial Star using Christmas tree ornament ?
Great excuse for getting yet another scope!!
GSO RC8 CF; Vixen 150mm F5 Newtonian c.1983; Super Polaris mount; DMD-1 controller; DIY Arduino controller; EQ6Pro mount; Synscan 3 controller; Avalon M-UNO; Vixen 60mm F12 refractor guidescope; Meade Lightbridge 12"; ASI1600MM-C; ATIK 420, Tamron 46A 70-210mm, ST80, Imaging Source DBK-21AU04-AS cam, Prostar/Toupcam GPCMOS0120KMB, ZWO ASI120MM-S, Bortle 5 sky.
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