Talk:Astrograph

Expanded article

The original article stated "An astrograph is basically a Newtonian reflector but uses a hyperbolic mirror instead of a parabolic mirror or spherical mirror". I have come across other statements [1] that:

An astrograph is a REFRACTOR with a short focal length and a wide field of view, intended for photographic use. Often the objective of an astrograph has more than two lenses. A Schmidt telescope or a Newtonian aren't astrographs, even if they are equipped for photography, because they aren't refractors. And the Newtonian doesn't even have a wide useful field of view.

• Is the no. 1 definition of an "astrograph" that it is a REFRACTOR?

• Or is "astrograph" defined by what it does? ---> Wide field large format photography or imaging of the night sky.

If it is the second definition then a Schmidt camera is an astrograph. If not then my weasel statment "although there are many (usually larger) reflecting designs such as the Ritchey-Chrétien and Catadioptrics such as the Schmidt camera" should probably be removed. (ratting my self out there ;^)). Halfblue 03:06, 18 October 2006 (UTC)

Astrographs are historically refracting telescopes of specific (sometimes exact) focal lengths used for Astrometry. Reflectors were not used for this task because spherical aberration at the film plane defeated the purpose of accurate measurement. Schmidt cameras seem to fall outside of the classification "astrograph" in most reliable references I have seen; maybe because their short F-ratios produce image plates that are non-standard (wide field) so cannot be used in conjunction with other astrographs for measuring. There seems to be a trend in amateur circles to call anything you can mount a camera on an "astrograph", not sure if this is technically correct. Will take a stab at a better definition. MrFloatingIP (talk) 16:35, 10 December 2009 (UTC)

Image copyright problem with Image:Pluto discovery plates.png

The image Image:Pluto discovery plates.png is used in this article under a claim of fair use, but it does not have an adequate explanation for why it meets the requirements for such images when used here. In particular, for each page the image is used on, it must have an explanation linking to that page which explains why it needs to be used on that page. Please check

• That there is a non-free use rationale on the image's description page for the use in this article.
• That this article is linked to from the image description page.

This is an automated notice by FairuseBot. For assistance on the image use policy, see Wikipedia:Media copyright questions. --20:54, 1 October 2008 (UTC)

External links modified

Hello fellow Wikipedians,

I have just modified one external link on Astrograph. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:

• Added archive https://web.archive.org/web/20060516050009/http://www.pietro.org:80/Astro_C5/Articles/KGraun_pluto_2003_Film.htm to http://www.pietro.org/Astro_C5/Articles/KGraun_pluto_2003_Film.htm
• Added {{dead link}} tag to http://aanda.u-strasbg.fr:2002/articles/aas/full/1999/09/ds8335/node2.html

When you have finished reviewing my changes, please set the checked parameter below to true or failed to let others know (documentation at {{Sourcecheck}}).

This message was posted before February 2018. After February 2018, "External links modified" talk page sections are no longer generated or monitored by InternetArchiveBot. No special action is required regarding these talk page notices, other than regular verification using the archive tool instructions below. Editors have permission to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the RfC before doing mass systematic removals. This message is updated dynamically through the template {{source check}} (last update: 5 June 2024).

• If you have discovered URLs which were erroneously considered dead by the bot, you can report them with this tool.
• If you found an error with any archives or the URLs themselves, you can fix them with this tool.

Cheers.—InternetArchiveBot (Report bug) 09:49, 20 October 2016 (UTC)