Talk:Toric lens

New version

I replaced this article with a translation of the Dutch article nl:Torische lens (which I also translated to German de:Torische Linse. Not knowing whether or not it is allowed to remove the Stub templates, I just "commented them out". HHahn (Talk) 15:44, 18 July 2011 (UTC)

When an article gets longer than about a screenful, you should remove the stub tags that are at the bottom of the article. The tags above, though, are project tags which should not be removed. They identify the article as being relevant to a particular project's work. --Srleffler (talk) 04:16, 19 July 2011 (UTC)

OK, but the project tags above should at least be re-assessed! Both "Start class" and "Low importance" are now at least disputable, I would say. So how can I call for such a reassessment? HHahn (Talk) 08:57, 19 July 2011 (UTC)

Cylinder lenses

Dear mr. Srleffer,

You added a "See also" link to Cylindrical lens. The "problem" is that this is not wrong... ;-) Neverthless, I would preferably not have exactly this link here. Most people are complete laymen in optics. When they get in touch with toric lenses, this will invariably be in a context of eyeglasses. Opticians, ophthalmologists and the like are trained in an area that does talk about optics, but using their own terminology, which in many cases is not in line with the terminology used in physics. On top of that, the medical profession is in general not very accurate in keeping apart 'types' of quantities (like dimensions), units, etc. So what they say, is often difficult to match with the physical terminology, especially for laypeople.

The ophthalmics world talks about "cylinders", without wondering how laypeople understand that term. "A cylinder is ground into a glass", or so. I put quite a bit of effort in finding out how to visualize such a "cylinder component". I wondered how to superimpose a cylinder on a sphere. Imagine an (x, y, z) coordinate system, with the z-axis along the (spherical) lens's optical axis. Then:

• Just add the "heights" z(x, y) of the sphere's and cylinder's surfaces?
• Add the distances z(x, y) of the sphere's and cylinder's surface points from the cylinder axis?
• Add the vectors (x, y, z) pointing from the origin (what origin: the focal point of the sphere, or some point along the cylinder axis, or whatever?) to the sphere's and cylinder's surface points?
• Or what else?

The only way I see out of this is considering the cylinder as a term in some series expansion describing the toric surcface. This approximation would only be valid at small opening angles (lens diameter / focal length). This is what I am saying in the footnote, "In this context, the term cylinder is based on a mathematical approximation, which is only valid for small corrective powers." Unfortunately, I could not find a literature reference for this interpretation so far. (By the way, "small opening angles" would be better, but to keep it readable for laymen, I preferred to say "small corrective powers")

I am afraid that a link to cylindrical lens might be confusing here...

HHahn (Talk) 13:37, 19 July 2011 (UTC)

The potential for confusion is a strong reason why there should be links between the two articles. The best way to deal with confusion is to confront it directly, by comparing and contrasting the topics. Obviously, it would be better to discuss the issue in the body of the article than to have a See also link, but even the latter gives an interested reader the potential to find the other article and compare the two. You have to assume that some readers are going to come here already confused about the issue, and either help to resolve the confusion or provide the tools they need to figure it out themselves.

I changed the text at cylindrical lens to clarify that these lenses are not typically used for ophthalmic purposes, and that toric lenses are usually used.--Srleffler (talk) 17:04, 19 July 2011 (UTC)

I edited this article too. See what you think, and please correct it if I have introduced any errors.--Srleffler (talk) 17:25, 19 July 2011 (UTC)

Hello mr. Srleffer, Thanks for your corrections. I will also copy them into the corresponding Dutch and German articles.

As for the factor (n – 1) you introduced, you are probably right. I just wasn't sure in this case of describing single lens surfaces. However, in this article, all lens powers get this same factor (though you forgot them in the next paragraph, "Working"), so all powers mentioned remain proportional anyway.

You replaced the non-breaking spaces by the {{nowrap}} template. Perfect. But you did not do so in the "Working" paragraph. When I did, the "=" gave problems. But strange enough, these problems did not occur in the previous paragraph. However, the solution is simple: just put the "=" between double braces: {{=}}. Furthermore, I put spaces around division slashes, which makes it better readble. (I always forget this...)

As for the cylinder misunderstanding, I swapped the sentence you added and the next one, because it was not obvious what "the latter" was exactly referring to.

HHahn (Talk) 10:21, 20 July 2011 (UTC)

The equals signs cause problems because template calls use equal signs to assign text to variables. The trick I used to get it to work is to assign the expression explicitly to a variable called "1": {{nowrap|1=<mathematical formula>}}. The {{=}} template works fine for this purpose as well.--Srleffler (talk) 04:00, 21 July 2011 (UTC)

Figure References Confusing And Useless On Mobile Page

There are two places in the article that read "(see figure at right)". It is unclear to me which photo is being referred to in which location.

On the mobile version the figures are even harder to connect to the text. On my phone the figures appear above the text. You can see the equivalent of my mobile phone's presentation by visiting the [mobile version] of this page and narrowing your browser window so that the first line reads "A toric lens is a lens with two different powers in". — Preceding unsigned comment added by Neil Smithline (talk • contribs) 22:26, 21 April 2012 (UTC)

Do you have similar problems with other articles? Referencing figures on Wikipedia is hard. We can't number figures, because as the article gets edited the numbering gets out of synch with the references. The best technique we have in general for referring to figures is to place a figure to the right or left of the paragraph and refer to it as "at right" or "at left". I understand that this will be broken on a mobile device. Are you also having problems with it on a computer-based web browser? Your comment seems to imply that you are. Are the two referenced images not directly to the right of the text that refers to them? On my screen they are correctly aligned for any useable window size. When I open the mobile version, the first of the two images is correctly aligned, but the second is not; as you noted it appears above the paragraph rather than beside it.

I tweaked the image layout so that the degenerate image can no longer appear to the right of the text that refers to the previous image. I can't do anything about the fact that the mobile version puts an image above the text even when the image tag explicitly calls for it to be placed to the right. The mobile version just simply has bad layout.--Srleffler (talk) 18:36, 22 April 2012 (UTC)