Talk:Wide-angle lens

From Wikipedia, the free encyclopedia

	Film Portal This article is within the scope of WikiProject Films. This project is a central gathering of editors working to build comprehensive and detailed articles for film topics on Wikipedia. If you would like to participate, you can edit the article attached to this page, or visit the project page, where you can join the project and/or contribute to the discussion.
Start This article has been rated as Start-Class on the quality scale. ??? This article has not yet received a rating on the priority scale.
Editing Guidelines Please remember these guidelines when editing a film article: If a non-film article already exists with the name of the film that you are trying to create an article for, disambiguate and use (film) in the title: Film Title (film) For more information see: Wikipedia:Naming conventions (films) When writing an article about a particular film, the general format should be a concise lead section, followed by a plot summary of no more than 900 words, production details, a cast list, a reception section, and references. Create an Infobox that tells all pertinent information about the film.
Additional Information: This article has been checked against the following criteria for B-Class status: Referencing and citation: not checked Coverage and accuracy: not checked Structure: not checked Grammar: not checked Supporting materials: not checked To fill out this checklist, please add the following to the template call: <!-- 1. It is suitably referenced, and all major points are appropriately cited. --> |B-Class-1=yes/no <!-- 2. It reasonably covers the topic, and does not contain major omissions or inaccuracies. --> |B-Class-2=yes/no <!-- 3. It has a defined structure, including a lead section and one or more sections of content. --> |B-Class-3=yes/no <!-- 4. It is free from major grammatical errors. --> |B-Class-4=yes/no <!-- 5. It contains appropriate supporting materials, such as an infobox, images, or diagrams. --> |B-Class-5=yes/no Related task forces (general): Filmmaking task force

Please add new comments, with section heads for new topics, at the bottom.

[edit] Project Filmmaking

I disagree; the attached article on wide-angle lenses does not belong in Filmmaking. Why? Because wide-angle lenses are not unique to motion picture making, either film or digital. In fact, they are probably less used in filmmaking than in still photography because of the ability of motion picture equipment to pan the scene. If the article is moved anywhere, it should be to one of the sections on photography. Anoneditor 22:28, 29 September 2006 (UTC)

I know it's old, but I might as well answer. You've probably noticed by now that projects overlap. There are lots of articles on photographic optics, for example, that are part of both project filmmaking and project physics. It doesn't hurt, except that their banners are obnoxiously large and distracting. Dicklyon 01:03, 9 December 2006 (UTC)

Thanks.Anoneditor 03:03, 9 December 2006 (UTC)

[edit] Normal lens

Dicklyon, I edited your edit of the second paragraph of the article because it left out the rationale for the use of the diagonal measure as the arbiter of the "normal lens." It also didn't mention the image sensor of digital cameras, an omission that might be confusing to readers who have less familiarity with the subject.Anoneditor 02:53, 9 December 2006 (UTC)

I left out the rationale because it is not correct. I used "film format" because I mis-read note 1. The "image aperture" terminology is pretty non-standard and confusing, in my opinion, because most people still don't get that an aperture is a hole, and the term aperture is so loaded in the meaning in photography already.

There are, unfortunately, some books that repeat the rationale about "more or less normal perspective", or "approximately as the eye sees it", neither of which makes any sense when you look at it. It's really just a convention to call a lens "normal" when its focal length is close to for format diagonal. Most books that tell you so don't include a "rationale" since there's really not one. The notion of a "normal" lens is over 100 years old, but the stuff about the perspective of the human eye seems to be only in more recent books. Dicklyon 04:49, 9 December 2006 (UTC)

I did some more book searching on books.google.com, and don't find any books that use the term "image aperture". But lots that use "film format" including some that use "camera/film format". We should really adopt a more standard term. As to the "rationale", if you'd like to include it, please do at least attribute it to a source, since it's not so widely accepted. Dicklyon 04:56, 9 December 2006 (UTC)

I don't guess it really matters, given the minimal significance of the issue, but my recollection is that this rationale was given repeatedly by the editors of Popular Photography and Modern Photography in the 1960s. Also, I think there's another consideration involved with "normal" perspective, i.e., the distance at which the photograph is viewed. Perspective distortion arises because photos are all viewed at a more or less standard distance. At a closer viewing distance the apparent perspective distortion of a wide angle lens disappears, giving the perspective one would see if standing at the camera when photo was taken. I don't think the issue of viewing distance was discussed in Perspective distortion (photography) to which this article links. Do you think is should be? Anoneditor 17:33, 9 December 2006 (UTC)

The idea of "correct perspective" has been around even longer than the idea of a normal lens, I think. You're right, it depends on viewing distance. The old derivations of DOF often assumed viewing at the distance that would give "correct" perspective, in calculating an acceptable COC. The distance is equal to focal length when you're making direct-view or contact prints. The COC was taken often as FL/1000, or later as 1/1000 of the focal length that would normally be used on that format. Eventually it was generally admitted that correct perspective was irrelevant, that photos are viewed all different ways, and that COC more like diagonal/1000 or diagonal/1500 would make more sense. Check out my draft paper on DOF all this history at dicklyon.com and maybe you'll find some bits worth quoting or some appropriate sources if you want to work on it; I'll look for a good source of the early use of format diagonal as "normal". Dicklyon 17:55, 9 December 2006 (UTC)

Here's a good bit from Dallmeyer, 1874: (book). He talks about the viewing distance for correct perspective, but also introduces the notion that the angle of view of the eye is only about 60 degrees. If you reduce this a bit more, as many have done, it can be used as the basis for a "normal" lens. But there is absolutely no basis for this 60 degree limit in human eye vision, so it's really a rationale that's just made up. People who have looked at it at all critically have simply dismissed it. Dicklyon 18:03, 9 December 2006 (UTC)

[edit] 0.7x

What does it mean to be a 0.7x wide angle lens? That the real image is 0.7x smaller than the filtered image? —Preceding unsigned comment added by 71.132.222.28 (talk) 05:49, 23 February 2008 (UTC)