Refractors for Dummies question
- The Happy Parrot
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Refractors for Dummies question
Maybe a star test and if so, what am I looking for?
- Lady Fraktor
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Re: Refractors for Dummies question
The two main things are checking the alignment of the focuser to the tube and then checking the collimation of the lens.
Do you have a laser collimator and a refractor collimation eyepiece?
https://agenaastro.com/agena-1-25-colli ... ctors.html
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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Re: Refractors for Dummies question
- Lady Fraktor
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Re: Refractors for Dummies question
If it does its good, if not is it focuser tube droop or misalignment.
If from the focuser use the three screws holding it to the tube to adjust.
Once you have the collimation eyepiece for it the you can easily check alignment of the doublet.
Does the telescope have collimation screws by the objective?
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)
The only culture I have is from yogurt
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Re: Refractors for Dummies question
Refractors: ES AR152 f/6.5 Achromat on Twilight II, Celestron 102mm XLT f/9.8 on Celestron Heavy Duty Alt Az mount, KOWA 90mm spotting scope
Binoculars: Celestron SkyMaster 15x70, Bushnell 10x50
Eyepieces: Various, GSO Superview, 9mm Plossl, Celestron 25mm Plossl
Camera: ZWO ASI 120
Naked Eye: Two Eyeballs
Latitude: 48.7229° N
- Ruud
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Re: Refractors for Dummies question
Look here for a few easy tests: https://starizona.com/tutorial/star-tes ... pe-optics/
Search Google for more star testing tricks. Pinched optics for instance is a frequently occurring aberration.
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Re: Refractors for Dummies question
Thank you LF. I removed the dew cap and I do not see any screws by the objective lens but there is a black ring over it. I'll try theLady Fraktor wrote: ↑Mon Mar 23, 2020 3:41 pm
Does the telescope have collimation screws by the objective?
star and laser tests before doing anything else. I believe it's actually fine as is, just curious at this point.
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Re: Refractors for Dummies question
Thanks Ruud. That's a very useful article on Starizona, especially this part:Ruud wrote: ↑Mon Mar 23, 2020 3:50 pm The best test would be a star test: looking at a high magnification image of a bright star. You do this in focus, but also out of focus, both in- and outside of best focus.
Look here for a few easy tests: https://starizona.com/tutorial/star-tes ... pe-optics/
Search Google for more star testing tricks. Pinched optics for instance is a frequently occurring aberration.
..."Almost without exception, all telescopes from reputable manufacturers will perform well enough that you could never notice any errors. If you plan on using your telescope to look at high-power, out-of-focus star images, maybe a star test is a practical examination of the scope’s optics. But in reality, as long as the telescope shows good images under normal use, a star test doesn’t mean too much."
- Lady Fraktor
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Re: Refractors for Dummies question
You are testing the telescope optics so leave the diagonal out when testing, the diagonal can be tested for alignment/ collimation on its own.
1st mag stars work well but a 2nd mag will work as well if available.
If your telescope gives pleasing views of Moon, planets and
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)
The only culture I have is from yogurt
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Re: Refractors for Dummies question
Will try on Sirius on the next clear night without the diagonal. I have a 12mm Starguider (55x) and a 9mm PL (73x). Will be interesting.
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Re: Refractors for Dummies question
If the stock one you should check it for alignment as well.
Place your laser collimaor into the diagonal and hold it against a mirror, the laser should bounce back to center and if not you can shim the mirror.
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)
The only culture I have is from yogurt
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Re: Refractors for Dummies question
I'm using a 1.25" Astro-Tech diagonal. It is held by a single screw on his telescope rather than a compression band so potentially it could be misaligned slightly but thankfully it is spot-on center with the laser on the diagonal.Lady Fraktor wrote: ↑Mon Mar 23, 2020 7:02 pm What diagonal are you using?
If the stock one you should check it for alignment as well.
Place your laser collimaor into the diagonal and hold it against a mirror, the laser should bounce back to center and if not you can shim the mirror.
It is snowing here today so no star tests tonight.
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Re: Refractors for Dummies question
A collimating eyepiece for refractors is new to me! Am I the only one? I just read one of the statements in the link:Lady Fraktor wrote: ↑Mon Mar 23, 2020 2:33 pm What refractor do you have?
The two main things are checking the alignment of the focuser to the tube and then checking the collimation of the lens.
Do you have a laser collimator and a refractor collimation eyepiece?
https://agenaastro.com/agena-1-25-colli ... ctors.html
"Use of this item assumes that your focuser is aligned properly with your telescope tube."
I would like a collimating eyepiece to point out any mis-collimation and not be based on assumptions.
Hmm so how does this work? Comparing to collimation of a Newt, mis-collimation of the primary lens of a refractor should be the equivalent of mis-collimation of the primary mirror of a Newt. Accepted. But mis-collimation of the focuser of a refractor, what is the equivalent for a Newt? Is it comparable to the mis-collimation of the secondary mirror of a Newt?
Trying to figure this out. Until then, I stick my Howie Glatter into the frac focuser tube and look at a dot that I put in the middle of my lens cap to see if it is in line. Sometimes I roll the frac on the ground and project on the door to see if it wiggles up and down.
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Re: Refractors for Dummies question
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)
The only culture I have is from yogurt
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Re: Refractors for Dummies question
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)
The only culture I have is from yogurt
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Re: Refractors for Dummies question
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Re: Refractors for Dummies question
Cheap rack and pinion focusers usually have slop in the (up/ down) as they are moved in and out but the view is centered close enough to the center of the lens that it is not very noticeable.
The longer the focal length the less you will notice focuser misalignment. Short tube refractors can even show
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)
The only culture I have is from yogurt
- Baurice
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Re: Refractors for Dummies question
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Re: Refractors for Dummies question
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.
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Re: Refractors for Dummies question
I was initially not happy with my Orion branded (identical to Celestron & Meade) 120mm f8.3 achromat's performance. Collimation made it brilliant. I did it myself. No need to return.
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