As a final check be sure that the inside and outside of focus images are symmetrical and identical. I use an artificial star so I don't need to waste observing time.The Happy Parrot wrote: ↑Sun Mar 29, 2020 8:55 pmYes, thanks Baurice. That is what I have done and I am pleased with the results. Stars are round and pin pointy, and with my 5.5mm Meade I' m able to split the doubles I tried so far. Will check Epsylon Lirae on the next clear clear night.
I am happy with the 102AZ telescope optics as they are and finding it pairs well the Z8.
Refractors for Dummies question
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Re: Refractors for Dummies question
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Re: Refractors for Dummies question
notFritzArgelander wrote: ↑Sun Mar 29, 2020 9:41 pmAs a final check be sure that the inside and outside of focus images are symmetrical and identical. I use an artificial star so I don't need to waste observing time.The Happy Parrot wrote: ↑Sun Mar 29, 2020 8:55 pmYes, thanks Baurice. That is what I have done and I am pleased with the results. Stars are round and pin pointy, and with my 5.5mm Meade I' m able to split the doubles I tried so far. Will check Epsylon Lirae on the next clear clear night.
I am happy with the 102AZ telescope optics as they are and finding it pairs well the Z8.
Can you elaborate for the neophytes?
Gary C
Celestron Astro Master 130mm f5 Newtonian GEM
Meade 114-EQ-DH f7.9 Newtonian w/ manual GEM
Bushnell 90mm f13.9 Catadioptric
Gskyer 80mm f5 Alt/Az refractor
Jason 10x50 Binoculars
Celestron 7x50 Binoculars
Svbony 2.1x42 Binoculars
(And a bunch of stuff I'm still trying to fix or find parts for.)
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Re: Refractors for Dummies question
Here is more details with pictures,GCoyote wrote: ↑Mon Mar 30, 2020 10:22 pmnotFritzArgelander wrote: ↑Sun Mar 29, 2020 9:41 pmAs a final check be sure that the inside and outside of focus images are symmetrical and identical. I use an artificial star so I don't need to waste observing time.The Happy Parrot wrote: ↑Sun Mar 29, 2020 8:55 pm
Yes, thanks Baurice. That is what I have done and I am pleased with the results. Stars are round and pin pointy, and with my 5.5mm Meade I' m able to split the doubles I tried so far. Will check Epsylon Lirae on the next clear clear night.
I am happy with the 102AZ telescope optics as they are and finding it pairs well the Z8.
Can you elaborate for the neophytes?
https://www.telescope-optics.net/star_t ... escope.htm
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Re: Refractors for Dummies question
Gary C
Celestron Astro Master 130mm f5 Newtonian GEM
Meade 114-EQ-DH f7.9 Newtonian w/ manual GEM
Bushnell 90mm f13.9 Catadioptric
Gskyer 80mm f5 Alt/Az refractor
Jason 10x50 Binoculars
Celestron 7x50 Binoculars
Svbony 2.1x42 Binoculars
(And a bunch of stuff I'm still trying to fix or find parts for.)
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Re: Refractors for Dummies question
It's probably more than you need to know. But keep it as a reference. Just look for perfectly identical inside and outside focus diffraction patterns as a quick check. Then refer to the link if there is something to worry.
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Re: Refractors for Dummies question
I didn't realize how much goes into optimizing optics. We've had a week of clouds, rain and snow and no chance to do any further testing yet. Last I looked I was able to split Castor and Mizar. Epsilon Lyrae was too low on the horizon behind my neighbor's house. I can see the four main stars on the trapezium in Orion's nebula but not E and F. In fairness, I rarely see those with my Z8 either due to
I will read through the text and pay special attention to the unobstructed view diffraction patterns. I will also try LF's suggestions out of curiosity.
In the mean time, I have a question. I've seen the terms over-correction and under-correction used in several places. What does that mean?
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Re: Refractors for Dummies question
You're very welcome.The Happy Parrot wrote: ↑Tue Mar 31, 2020 7:52 pm Gosh, thanks nFA! I am slowly crawling through the text as best I can. Thank you.
They are good suggestions to try.I didn't realize how much goes into optimizing optics. We've had a week of clouds, rain and snow and no chance to do any further testing yet. Last I looked I was able to split Castor and Mizar. Epsilon Lyrae was too low on the horizon behind my neighbor's house. I can see the four main stars on the trapezium in Orion's nebula but not E and F. In fairness, I rarely see those with my Z8 either due to lp in my area and viewing conditions.
I will read through the text and pay special attention to the unobstructed view diffraction patterns. I will also try LF's suggestions out of curiosity.
It's easiest to understand in terms of glasses. Overcorrection means that the lens is "too strong". Undercorrection means "too weak". Optics (and glasses) can be specified by 1) the radius of curvature of the lens surfaces or 2) the diopter (reciprocal of the focal length in meters). For glasses a diopter value is used for the relatively simple lenses involved. For telescopes with more surfaces the radius of curvature is used. In a Fraunhofer achromat each lens has 2 surfaces, 4 different radii of curvature. Other designs might economize by making some of the surfaces have the same curvature.In the mean time, I have a question. I've seen the terms over-correction and under-correction used in several places. What does that mean?
These different radii combine to give a perfect star test in a perfectly executed scope.With under correction more light rays are misdirected away from focus outside the normal focus point. For overcorrection the reverse is true and some rays come to a focus too early. So the spherical aberration or bad focusing of the light rays has that sort of analogy with corrective glasses.
There's a handy book, very practical, little math: https://www.willbell.com/tm/tm5.htm
And there is a handy calculator that can generate pictures of what the diffraction patterns should look like: http://aberrator.astronomy.net
It's something you can do with your gear on even a rainy night.
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Re: Refractors for Dummies question
More on that later.
Be and stay well!
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Re: Refractors for Dummies question
After the test I did a leisurely galaxy 5K with stops in M42, M44, M45, M47, M51, M81 and M82, M94, M101 (first time), M106 and pit stops at the Sunflower and
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Re: Refractors for Dummies question
If the telescope is putting up excellent views I would not worry about it other than checking for curiosity.
A nice tour as well
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
Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102
Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Tak prism, TAL, Vixen
Eyepieces: Antares to Zeiss (1000101)
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