Talk:List of largest optical refracting telescopes

message: There is also the 12 1/4 inch Grubb refractor installed in Oxford 1874. It is currently housed in Keele Observatory: http://www.astro.keele.ac.uk/~obs/
http://www.astro.keele.ac.uk/~obs/optics_main.htm
The salient details for this are aperture 12.25 inches (310 mm), focal length 4.39 metres  —Preceding unsigned comment added by Old astronomer (talk • contribs) 13:02, 8 November 2009 (UTC)
replies: text: The problem is that, in today's day and age, it's pretty easy to have a 12 to 14-inch refractor.  There are probably hundreds if not thousands out there, and only those that are really old were "large" back in their time period, but that is now a historical note and by today's standards they shouldn't be considered "among the largest".  I think this list shouldn't include anything below 16 inches in today's day and age. 149.97.32.58 (talk) 23:15, 8 January 2013 (UTC)
thread_title: Others missing

message: I'm sorry but the last edit make the table look ugly.
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The article that Paris 1900 Exposition links to (Exposition Universelle (1900)) dose not talk about the telescope: could someone knowledgeable about the topic fix this? --Canageek 19:29, Jun 12, 2005 (UTC)
===Paris 1900 refractor===
If I remember well, this instrument was a DOUBLE refractor - the lenses optimized for visual and photographic use, resp. Source: Sky & Telescope somewhen in the sixties - perhaps J. Ashbrook's column "Astronomical Scrapbook".
In addition I seriously doubt that (vertically mounted) lenses were designed to sag into correct figure.  --ECeDee 19:22, 19 July 2005 (UTC)
replies: text: See also 1911britannica - there is a hint in favour of double refractor --84.178.136.47 19:37, 19 July 2005 (UTC)

text: The double refractor was at Meudon (Paris Observatory). The Paris 1900 Exposition instrument was a simple refractor and was horizontal (see article), it was a total failure I think the glass was deformed by its own weight. Ericd 14:53, 20 July 2005 (UTC)
replies: text: I remembered not very well. Today finally I got hand on my source: J. Ashbrook's column "Astronomical Scrapbook" in Sky & Telescope, Aug. 1958, p. 509. The Great Paris Refractor (Exposition instrument) in fact was single, but had two lenses (see article). This agrees with the Britannica information. --ECeDee 22:28, 1 March 2006 (UTC)
thread_title: Comments

message: If I remember well, this instrument was a DOUBLE refractor - the lenses optimized for visual and photographic use, resp. Source: Sky & Telescope somewhen in the sixties - perhaps J. Ashbrook's column "Astronomical Scrapbook".
In addition I seriously doubt that (vertically mounted) lenses were designed to sag into correct figure.  --ECeDee 19:22, 19 July 2005 (UTC)
replies: text: See also 1911britannica - there is a hint in favour of double refractor --84.178.136.47 19:37, 19 July 2005 (UTC)

text: The double refractor was at Meudon (Paris Observatory). The Paris 1900 Exposition instrument was a simple refractor and was horizontal (see article), it was a total failure I think the glass was deformed by its own weight. Ericd 14:53, 20 July 2005 (UTC)
replies: text: I remembered not very well. Today finally I got hand on my source: J. Ashbrook's column "Astronomical Scrapbook" in Sky & Telescope, Aug. 1958, p. 509. The Great Paris Refractor (Exposition instrument) in fact was single, but had two lenses (see article). This agrees with the Britannica information. --ECeDee 22:28, 1 March 2006 (UTC)
thread_title: Paris 1900 refractor

message: Surely somone has made a bigger optical refracting telescope in the last 100 years?  Some of the stubs i've worked on have 5 meter diameter telescopes, the radio telescopes can get up above 50 (of course they aren't refracting optical)--Rayc 23:45, 26 October 2005 (UTC)
replies: text: Maybe we just learned that big refracters aren't very practical, and that very large aperture telescopes should be reflectors?  149.97.32.58 (talk) 23:20, 8 January 2013 (UTC)
thread_title: Bigger?

message: The folks at Lick claim the 36 inch is actualy the 2 largest in the world.  This claim is also repeated in the DVD sold at the gift shop.  Who's right? Jwissick(t)(c) 23:18, 6 November 2005 (UTC)
thread_title:  Lick ranking 

message: How can this instrument be the same that the small refractor of Berlin when they heve different focal length ? I know both are Zeiss instruments. Was one modified later ? I know there is a 50cm at Nice that was improved with a better Zeiss lens given as reparation for war.  Ericd 14:09, 2 May 2007 (UTC)
thread_title:  Belgrade Refractor 

message: There is a 30-inch amateur refractor in the UK - see Hanwell Community Observatory. It was constructed by John Wall to his own design and comprises a single full aperture objective and several sub-aperture corrector lenses placed at/near the prime focus. The design apparently removes most false colour and is the basis for a commercially available 8-inch apochromatic refractor.  —Preceding unsigned comment added by 90.196.231.155 (talk) 09:56, 15 October 2010 (UTC)
thread_title:  The 'John Wall' telescope: a 30-inch amateur refractor in the UK 

message: The list should include this one: http://assa.saao.ac.za/html/his-tel-innes-67c_26_5i.html. It is still in Johannesburg. The list mentions a scope located at Johannesburg that was moved to Australia - I don't think that is correct, and even if it is, it is different to the telescope I have provided a link to, which is definitely still in Johannesburg. I looked through it as a kid in thr 1980s. I believe it is the largest refractor in the southern hemisphere, so it would be good to get this entry right.  — Preceding unsigned comment added by 83.81.191.5 (talk) 11:56, 20 June 2011 (UTC)
replies: text: -)
This statement is essentially correct. The Union Observatory (in Johannesburg) was commissioned around 1925 or 1926. The director at the time was Robert Innes and the 26.5" refractor was ordered from Thomas Grubb and Son. Grubb was purchased by Parsons while the scope was being made. This instrument was abandoned in the early 1980's but was rescued by an amateur effort and is now used for public outreach and school tours. I was an occasional operator of this telescope until 2007.
The 26" telescope referred to in the Yale southern station was originally installed in the Boyden observatory (near Bloemfontein, South Africa), not in the Union Observatoy, Johannesburg. It was moved to Mt Stromlo (Australia) around 1952 and - as the list records destroyed in a fire. I have heard that this instrument was fabricated by Alvin Clarke but I have not been able to confirm whether this is accurate.NoiseJammer (talk) 01:46, 30 March 2017 (UTC)
thread_title:  THe Innes Refractor, Johannesburg 

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message: I don't know anything about telescopes.  Are the imperial measurements (manually converted from metric) really supposed to be annotated with prime (′ U+2032) and double prime (″ U+2033)?  When I noticed it at the Yerkes Observatory table entry, I thought it was a one-off.  Not so.  There are four prime characters denoting feet but 64 double prime characters denoting inches.  Is that how it is supposed to be done for astronomical instruments?
—Trappist the monk (talk) 23:28, 4 October 2023 (UTC)
thread_title:  prime and double prime?