Should A Refractor Be Called A Reflector?

Discuss your refractor type scopes here.
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Refractordude
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Should A Refractor Be Called A Reflector?

#1

Post by Refractordude » Mon Nov 11, 2019 8:05 pm

With the use of a diagonal, I think so. The diagonal REFLECTS light into the eyepiece.
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#2

Post by JayTee » Mon Nov 11, 2019 8:38 pm

NOPE!

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#3

Post by Voyageur » Mon Nov 11, 2019 8:47 pm

Granted, when you use a mirror diagonal with a refractor, the image created by the refraction of light is reflected to the eyepiece, just as your diagrams show. Using similar "logic" you could also say that a reflector is a refractor because the image created by reflection is refracted by the eyepiece. :roll:

But why would you want to do either of those things? The terms refractor and reflector make a practical and useful distinction between the two types of scopes on the basis of their optical properties and construction. So I'd say let's leave our terminology as it is!
Last edited by Voyageur on Mon Nov 11, 2019 9:16 pm, edited 1 time in total.
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#4

Post by AntennaGuy » Mon Nov 11, 2019 9:04 pm

I agree with JT. Although the optical quality of a diagonal is important, its primary role is simply to re-direct the beam. The image forming mechanisms are either lenses or mirrors. Since eyepieces are normally made from lenses, that leaves the main objective (lens = refractor, or mirror = reflector) as the determinant of whether a telescope is a reflector or refractor (otherwise we'd have to call nearly all telescopes refractors). There are some potentially confusing mixtures (e.g., Schmidt-Cassegrain, Maksutov, etc.). But those are normally still considered to be reflectors, while their aperture-sized lens-type elements are considered to be "correctors."
* Celestron C6 SCT on a Twilight 1 Alt-Az mount
* Meade 323 refractor on a manual equatorial mount.
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#5

Post by pakarinen » Mon Nov 11, 2019 9:14 pm

Should rotini be called linguini? I think not, but I could be persuaded to call it "Bob".
If you don't understand your noise, you cannot reliably extract a meaningful signal.
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#6

Post by JayTee » Mon Nov 11, 2019 9:17 pm

I'm sorry, I can't resist, should a golf club really be called a hammer. They are both tools and they both hit things.

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#7

Post by notFritzArgelander » Mon Nov 11, 2019 9:41 pm

AntennaGuy wrote:
Mon Nov 11, 2019 9:04 pm
I agree with JT. Although the optical quality of a diagonal is important, its primary role is simply to re-direct the beam. The image forming mechanisms are either lenses or mirrors. Since eyepieces are normally made from lenses, that leaves the main objective (lens = refractor, or mirror = reflector) as the determinant of whether a telescope is a reflector or refractor (otherwise we'd have to call nearly all telescopes refractors). There are some potentially confusing mixtures (e.g., Schmidt-Cassegrain, Maksutov, etc.). But those are normally still considered to be reflectors, while their aperture-sized lens-type elements are considered to be "correctors."
Refractors are dioptrics.
Newtonians, classical Cassegrains and all mirror systems are catoptrics.
Maksutovs, SCTs that mix lenses and mirrors are catadioptrics.

The use of a diagonal is a nonessential option.
Scopes: Refractors: Orion ST80, SV ED80 A f7; Newtonians: Z12 f5; Catadioptrics: VMC110L, Intes MK66. EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker III, Vixen Porta II, Celestron CG5, Orion Sirius EQG
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#8

Post by Refractordude » Mon Nov 11, 2019 9:48 pm

notFritzArgelander wrote:
Mon Nov 11, 2019 9:41 pm
AntennaGuy wrote:
Mon Nov 11, 2019 9:04 pm
I agree with JT. Although the optical quality of a diagonal is important, its primary role is simply to re-direct the beam. The image forming mechanisms are either lenses or mirrors. Since eyepieces are normally made from lenses, that leaves the main objective (lens = refractor, or mirror = reflector) as the determinant of whether a telescope is a reflector or refractor (otherwise we'd have to call nearly all telescopes refractors). There are some potentially confusing mixtures (e.g., Schmidt-Cassegrain, Maksutov, etc.). But those are normally still considered to be reflectors, while their aperture-sized lens-type elements are considered to be "correctors."
Refractors are dioptrics.
Newtonians, classical Cassegrains and all mirror systems are catoptrics.
Maksutovs, SCTs that mix lenses and mirrors are catadioptrics.

The use of a diagonal is a nonessential option.
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#9

Post by Don Quixote » Mon Nov 11, 2019 9:50 pm

Have not read any but the OP.
Dude ! WTF ?!
HELL NO ! 😊
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#10

Post by Bigzmey » Mon Nov 11, 2019 11:40 pm

When I saw the title, I thought it should be called reflector, because it helps us to reflect on wonders of the sky. :)
Scopes: Stellarvue: SV102 ED F7; Celestron: 9.25" EdgeHD F10, 8" SCT F10, 6" SCT F10, Omni XLT 150R Achro F5, Onyx 80ED F6.3; Meade: 80ST Achro F5.
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#11

Post by j.gardavsky » Tue Nov 12, 2019 11:29 am

Yours according to the pic is diagonal double-dioptrix,
because both the light gathering optics and the eyepiece are dioptrics, and there is a zenith diagonal in between.

The other one, listed by not_Fritz, would be catadioptric-diagonal-dioptrix, ...
Regarding the old German Schiefspiegler, I have nothing better than calling it Schiefspieglerteutonics.

The Fraunhofer tracking EQ mount might be Equatoreanum penduli moveatur Fraunhoferi, ...

ZEISS has decided to call their refracting spotting scope, Diascope.
Following ZEISS, Thomas Baader has renamed the astroplanar remake into Eudiascopic

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#12

Post by John Baars » Fri Nov 15, 2019 9:14 am

:sprefac: Pffffffff.....I am glad my refractors are still refractors..... :sprefac:
Telescopes in Schiedam : SW 150mm F/5 Achromat, SW Evostar 120ED F/7.5, Vixen 102ED F/9, OMC140 maksutov F/14.3, SW 102MAK F/13 on Vixen GPDX.
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#13

Post by yobbo89 » Fri Nov 15, 2019 10:43 am

The topic reminds me of folded refractors which have 2 or more mirrors in them as well as a refracting front lense .

Here are some images from the web
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#14

Post by KathyNS » Fri Nov 15, 2019 2:00 pm

My Newtonian is a catadioptric, because it really doesn't work properly without a coma corrector.
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#15

Post by Don Alvarez » Fri Nov 15, 2019 2:24 pm

me-yelling-at-my-cat-to-not-eat-my-salad-58434960.png
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#16

Post by Marcelo F. » Fri Nov 15, 2019 2:31 pm

Image
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#17

Post by helicon » Fri Nov 15, 2019 5:44 pm

I also am glad that my refractor is truly a refractor. Though I could call it "Fred".
-Michael
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#18

Post by j.gardavsky » Fri Nov 15, 2019 7:55 pm

KathyNS wrote:
Fri Nov 15, 2019 2:00 pm
My Newtonian is a catadioptric, because it really doesn't work properly without a coma corrector.
Kathy,
and when it makes spikes around the stars,
then it is catadioptric asterix,

JG
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#19

Post by russmax » Sat Jan 04, 2020 1:08 am

A refractor is called a refractor because that is its name. Likewise with a reflector.
Language is by usage, so if you overthink it, people might tease you for it, as shown in the posts above.
--Russmax
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#20

Post by Mandrew » Thu Jan 23, 2020 6:53 am

It’s a telescope!
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