Talk:Spherical aberration

Things needed in 2005

I thought this subject needed a short, concise article instead of being redirected to the complex article on aberration in general. If someone is really strongly against this then go ahead and change it back. Rsduhamel 03:12, 31 Dec 2004 (UTC)

No, that's a fine idea. As much as I like the old Britannica article, I nevertheless agree with the idea of splitting the important named effects into small articles. In the end, but this would need a tough amount of work, all the elementary treament of aberrations should be separate articles, and the Aberration in optical systems would be reduced to (still lengthy)

• Definition and overview
• History
• Integreated mathematical treatment (eiconal)

Pjacobi 11:23, 2005 Feb 23 (UTC)

The page really needs a simple line drawing of light rays being focused at different distances depending on their radial positions. Mglg 20:45, 1 June 2006 (UTC)

There are some simple pictures of spherical aberration here: http://www.cartage.org.lb/en/themes/sciences/physics/Optics/Optical/Lens/Lens.htm Probably the best I have found on the web so far.

"Short focal ratio" versus "small f-number"

For me at least, the article would be easier to understand if the term "short focal ratio" were replaced with "small f-number." Clicking on the "focal ratio" hyperlink takes the reader to f-number after all. I guess different parts of the optics community use different jargon. Other than this quibble, I think the article is excellent. Alison Chaiken 18:23, 12 October 2006 (UTC)

As noted, fast is the popular term in photography. It clearly indicates what is desirable and not so easy to achieve. Also, photography most often discusses it in terms of aperture (that is 1/f-number), which makes more sense if you consider the f/() a fraction with the actual number in the denominator. That is, f/4 is larger than f/16, even though 4 is smaller than 16. The result, though, is that "small f-number" seems clumsy to say, even though technically more correct. Photographers never say "increase the f-number", but usually say "stop down" instead. The reverse is "open up" not "stop up", maybe to avoid confusion with clogged drains. I am not sure how it is done in non-photographic optics. Gah4 (talk) 21:24, 26 August 2014 (UTC)

Interference?

The various pictures of point-spread functions appear to show interference patterns, which could confuse people expecting to see the kind of bokeh you see in photography rather than what you find in microscopy. Could someone more familiar with the details add that? —Ben FrantzDale 00:34, 13 November 2007 (UTC)

Regularity of rings

I expected the rings to be evenly-spaced and fading toward the edges according to Fraunhofer diffraction, yet the beautiful illustrations show brighter rings at the outside and decreasing frequency. What's up with that? 155.212.242.34 (talk) 21:28, 20 November 2007 (UTC)

Near field, it should be Fresnel diffraction instead. There are some nice pictures there, too. Gah4 (talk) 21:07, 26 August 2014 (UTC)

Why spherical?

I think it should be stated early that spherical surfaces are easier to grind, and so popular for optical devices. (Mirrors and lenses.) It is explained later that the result is that it is easier to make many spherical lenses than one aspherical one, and is the whole reason why spherical aberration is important. This should be moved up and expanded. Gah4 (talk) 21:11, 26 August 2014 (UTC)

Hasn't changed yet, I will see what I can do. Gah4 (talk) 07:37, 11 January 2019 (UTC)

Thanks for the improvements to my improvements. Next: due to the increased refraction of light rays when they strike a lens or a reflection of light rays when they strike a mirror near its edge. This isn't quite right. The way a lens or curved mirror works is that the change increases with radius (first order change). The important part of spherical aberration is second order. It is harder to explain a second derivative than a first derivative. Gah4 (talk) 07:38, 12 January 2019 (UTC)

Removed orphan text

I moved this text here:

Longitudinal or axial spherical aberration

When light rays are passed through an uncorrected convex lens, the rays at the periphery are bent more than the ones passing near the optical center. Thus, the peripheral rays produce many focal points on the principal axis before the actual focus. This is called longitudinal or axial spherical aberration.

It seemed to repeat the description of the main phenomenon of the article. So I moved it here. It does, however, contain the additional vocabulary words longitudinal spherical aberration and axial spherical aberration, which appear nowhere else in the article. Maybe these should be re-integrated into the article.

Also, the description of the phenomenon given in this text is quite clear -- perhaps clearer than the present introduction. Was this once the introduction to the article?

178.38.191.160 (talk) 11:44, 21 May 2015 (UTC)

Acuña-Romo image

Regarding the image (to the the right):

description

@Srleffler: Why not just change the "description" from "Acuña-Romo lens" to something potentially more appropriate? X1\ (talk) 22:52, 15 July 2019 (UTC)

Below, Srleffler comment is copied to here from my Talk page. X1\ (talk) 22:57, 15 July 2019 (UTC)

I reverted you at Spherical aberration. That image does not appear to be an image of an "Acuña-Romo lens" per se but rather an illustration of the fact that the equation allows one to form a second surface that corrects any aberrations introduced by the first surface of a lens. Presenting it with the caption "Acuña-Romo lens" is misleading. No one would design an actual lens with that crazy profile. A raytrace image of an actual practical Acuña-Romo lens design would be a better fit for the article.

For reference, see Draft:Acuña-Romo equation. X1\ (talk) 23:19, 15 July 2019 (UTC)

I thought about that, but didn't feel that this image was very useful in the context of this article. A different caption could make it less misleading, but still wouldn't easily allow the image to convey any useful information about Acuña-Romo lenses. A properly raytraced image showing a practical Acuña-Romo lens design would be more appropriate for this article.--Srleffler (talk) 03:21, 16 July 2019 (UTC)

Acuña-Romo equation

Re: this edit: I chose only Spanish because only that was the only one of the linked articles that was well developed. I left the links to the other articles today, but removed the {{ill}} template. Red links are only for viable article topics. The Acuña-Romo equation is not a viable article topic on the English Wikipedia. The equation is not yet notable. Even when notable, the topic is probably better covered in an existing article (possibly this one). It's not clear the topic merits an extensive exposition of the equation (WP:UNDUE). Before we go any further, there at least needs to be some coverage in independent secondary reliable sources. Right now, there are a couple of blog posts and Acuña and Romo citing their own work.

Other language Wikipedias have their own standards, so the existence of articles in other languages is not relevant.--Srleffler (talk) 03:58, 16 July 2019 (UTC)

Should we say Acuna-Romo solved the Wasserman-Wolf problem

Should we say Acuna-Romo solved the Wasserman-Wolf problem as described in [1] - then the red-link could redirect here ? - Rod57 (talk) 12:13, 12 August 2019 (UTC)

Mention Descartes' work

Should this page not discuss [2]. I.e. many people seem to think that Acuna-Romo solved an aberration problem for the first time while Descartes seems to have taken care of that many centuries ago. Acuna-Aroma try to solve a more sophisticated problem: given the shape of one side of the lens, what shape should the other side take in order to avoid aberration? That said, their paper looks suspicious in that they appear to be merely solving algebraic equations while one would expect that the problem should require solving (delay) ODE's of some sort. — Preceding unsigned comment added by 109.131.16.178 (talk) 21:18, 7 December 2019 (UTC)

Yes, we should definitely talk about Descartes' work. I moved your addition down a bit, since I think it's important to cover practical solutions before abstract theoretical ones. In practice, aberration is not normally corrected using aplanatic lenses. The existance of closed-form expressions for designing aspheric surfaces is not particularly important, given that a modern computer running ray tracing software can optimize a singlet lens design in minutes or less.--Srleffler (talk) 23:52, 7 December 2019 (UTC)

My confusion

"The effect is proportional to the fourth power of the diameter and inversely proportional to the third power of the focal length". This is what confuses me, as I'm not sure how the effect is measured.--CaffeineP (talk) 03:55, 7 April 2021 (UTC)