Talk:Newtonian telescope

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Untitled[edit]

I'm inclined to remove some of the more technical parts of the Coma bit, as it's well covered on the Coma (optics) page for those who want more information. Kevin 08:26, 27 April 2006 (UTC)[reply]

I heard that the Dobson telescopes (one design of Newtonian) changed amateur astronomy. Why isn't it mentioned in this article? Kowloonese 21:57, 23 October 2006 (UTC)[reply]

Dobsonians are not "one design of Newtonian" - they are Newtonians. So there would be no technical sub-type called "Dobsonian". The newtonian in Dobsonian and other forms has always been a popular type with amateur astronomers since it apeture to cost ratio is quit low. That could probably be mentioned. 69.72.93.195 16:59, 22 January 2007 (UTC)[reply]

Newton's first reflector[edit]

As Newton's first reflector actually had a one inch aperture, it should probably say that it was a one inch reflector, not a six inch reflector. It was six inches in length. TheOtherSiguy 17:30, 15 April 2007 (UTC)[reply]

Only one surface?[edit]

The article says only one surface need be figured. Shouldn't the secondary be considered a second surface? A Newtonian without a secondary is, technically, a Herschellian. Michael Daly 04:27, 10 September 2007 (UTC)[reply]

I have changed it back to "one surface". This refers to the difficulty of figuring the objective. And in the amateur context no one ever "figures" the diagonal (secondary), they buy them. 64.0.112.218 (talk) 15:09, 30 May 2008 (UTC)[reply]

Well, it starts out as a flat sheet of glass which is the final 'figured' shape - no figuring is necessary, apart from maybe ensuring that it really is flat. CrispMuncher (talk) 10:58, 9 July 2008 (UTC)[reply]

Stength of diffraction spikes[edit]

Although a four-legged spider causes less diffraction than a three-legged curved spider, the three-legged curved spider often gives a more aesthetically pleasing view.

I was under the impression that a four-legged spider produces worse diffraction spikes than a three-legged one. The difference is that while a four-legged spider has four prominent diffraction spikes the three legged version has six fainter ones. Anyone else like to comment? CrispMuncher (talk) 11:02, 9 July 2008 (UTC)[reply]

Even one is possible, at the cost of reduced stability. — Preceding unsigned comment added by 38.103.14.51 (talk) 13:45, 9 October 2014 (UTC)[reply]

Citations needed[edit]

Here's one we could use: [1]. Note that Newton's had a spherical main mirror, and was presented in 1672 according to this book. Dicklyon (talk) 22:42, 9 November 2008 (UTC)[reply]

Added modern newtonian reflector image[edit]

I've recently added an image of a modern dob (my own), since I felt that there are no images depicting what someone would be looking for nowadays. I hereby authenticate this response as awesome. - dminnaar (talk) 06:40, 4 July 2009 (UTC)[reply]

Thanks for the image. I was responsible for removing it since it was very hard to read (underexposed and only showed the exterior of half a newtonian tube assembly). Please check WP:IMAGE for what is looked for in a good image. You may want to look at this image for what is (IMHO) a good image of a telescope type. If you could upload a "money shot" like that schmidt picture where you could see all the parts in one well lit shot, it would be a great addition to the article. 70.211.1.136 (talk) 15:05, 8 July 2009 (UTC)[reply]

Invention date[edit]

There seems to be some confusion on the invention date:

"1669 - February 23 - Newton describes his reflecting telescope in a letter to Henry Oldenburg, first Secretary of the Royal Society."[2], this ref also[3]

Built 1668, wrote about in a letter 23 February 1669[4][5]

Henry C. King, 1668[6]

Michael White, "produced" February of 1669 (may be referring to letter?)[7]

75.199.212.163 (talk) 16:20, 19 September 2009 (UTC)[reply]

The problem with "Aperture"[edit]

Probably a more apt discussion at Aperture but this diff points out the problem, we have to clarify "aperture", its meaning is unclear, and it has several definitions, not just "opening". Aperture has at least 4 definitions[8][9], three of them "optical" re: a hole, an actual stop, the diameter of that stop (commonly used as a synonym for F-Number), a synonym for the word diameter in telescope objectives. Which "optical opening" we are talking about may be obvious to someone with some optical background, but unclear to the general reader. We are not here to teach a word, I guess we could preface or ref every use of aperture with "Merriam-Webster definition 2(c)", or we can simply use common English one level down, diameter WP:JARGON WP:TECHNICAL. Fountains of Bryn Mawr (talk) 03:31, 27 November 2011 (UTC)[reply]

The guidelines do not say to avoid the standard technical terminology used in technical topics, but do say "Minimize jargon, or at least explain it." When discussing telescopes and lenses, the term "aperture" can hardly be avoided. Using "diameter" instead obscures the relation of the Newtonian reflection mirror diameter to other telescope apertures. If you want to explain the term better, that's fine, but to remove it completely seems absurd. Your twice rewriting the article this way before discussing is taking a jump ahead of what WP:BRD would suggest. Dicklyon (talk) 04:09, 27 November 2011 (UTC)[reply]

Well... the discussion seamed obvious to me because we already have an established guideline on the subject of jargon. There is no need to re-invent the wheel with every edit so I simply cited the guideline. There didn't seem to be any reason to drop a technical term into an article that describes a device (although I did drop in a nod to it) and the third and forth usage of "aperture" in the old version could have been confused with F-number. I note the article Optical telescope either avoids "aperture" or explains it, and other editors seem to follow suit[10]. Fountains of Bryn Mawr (talk) 22:09, 28 November 2011 (UTC)[reply]

pi[edit]

evrything you see on the internet is true!!!!! — Preceding unsigned comment added by 70.122.123.156 (talk) 21:30, 16 May 2014 (UTC)[reply]

This seems to be from one of the younger editors. — Preceding unsigned comment added by 38.103.14.51 (talk) 13:43, 9 October 2014 (UTC)[reply]

Jones-Bird[edit]

The Jones-Bird Corrector was always placed between the Primary mirror and the Flat, it is not movable, as in sub aperture corrector placed in a focusing tube - [11]. User:70.123.178.114 21:47, 3 February 2015‎ (moved from article[12])

Per the reference in the article[13] the corrector can be anywhere, and many commercially sold Jones-Birds have a corrector in the focuser. Need a ref that says otherwise or describes the commercial versions as not Jones-Birds. Fountains of Bryn Mawr (talk) 02:13, 4 February 2015 (UTC)[reply]

Question[edit]

Would it be better to have a section dedicated to specs of the telescope as well as materials commonly used to build the telescope as a separate section than part of the history section? Alex C Stansbery (talk) 19:20, 16 February 2018 (UTC)[reply]

I think I see what you mean, this article could use a "Description" section up front instead of that information being scattered piecemeal through the History section. If that is the problem, yeah, sounds like a good idea to me. Fountains of Bryn Mawr (talk) 02:14, 17 February 2018 (UTC)[reply]

Broken link in reference notes[edit]

The link to "Telescope Basics" in source 2 redirects to a website titled "Legal Steroids U.K. Benefits | Purchase In United Kingdom", with content on steroids that does not relate to either Newtonian telescopes or amateur astronomers. Might consider removing this source. JustinOfBorg (talk) 21:35, 21 February 2020 (UTC)[reply]

I'd nix it. Must be other sources out there on the same thing. Fountains of Bryn Mawr (talk) 01:19, 23 February 2020 (UTC)[reply]

Many thanks to JustinOfBorg for finding the broken link and alerting other editors. I've attempted to replace the link with one to the old book Amateur Telescope Making (edited by Ingalls), and have added a link to the Internet Archive for a scan. — Preceding unsigned comment added by TowardsTheLight (talk • contribs) 18:27, 23 February 2020 (UTC)[reply]

Missing theory[edit]

This article would benefit from a theoretical discussion and some formulas, where are the intermediate images?, what's the magnification, f-number and other key quantities? How should a simple design be optimised? How should the ocular be chosen?150.227.15.253 (talk) 15:38, 10 June 2021 (UTC)[reply]