Talk:Science of photography

Should

This page should be an intelligent redirection page towards the correct terms and science to describe the workings of any aspect of the photographic process (digital, film, etc). It should include anything pertinent to photography that is too specific for the page about the specific science, but too technical to be explained on the photography page. In a quick search, most of the information is available already on wikipedia, but it could be explained with more relevance towards actually building cameras and taking pictures (engineering concerns, generating artistic effects, etc). (I do not claim to have achieved this yet; what exists currently is a brief, brief overview). This page does not intend to be a collection of camera manuals, nor a page on how to take good pictures.—The preceding unsigned comment was added by Hvc (talk • contribs) .

I agree with Hvc above about the scope and direction this page needs. In recent edits this page seems to have become confusing and disjointed with long rambling passages that may be copied and pasted from somewhere. I am new to this "wikipedia business" so I am reluctant to make the wholesale changes I believe this page needs.

I think it should be just a brief discussion of the general nature of photography, and links to more specific pages elsewhere. 1p2o3i 17:41, 4 September 2006 (UTC)

Quality of this page

This page was till a few days ago in bad shape. Just a note here to thank the latest editor, I believe it was Imroy, for great work making it much better. —Preceding unsigned comment added by 1p2o3i (talk • contribs)

Yep, that was me. Thanks. I came upon this page randomly and noticed its poor shape. The first thing I did was remove the large amount of very poorly written content that Cinegrefx/210.210.36.160 had recently copied into the article [1] (some people seem to treat Wikipedia as a place to dump any old content they can lay their hands on, without any thought given to the structure or cohesion of the article). Then I went through and did a lot of editing of the text and formatting. I'm sure a lot more could be done with this article, I simply did the things that were easy and obvious to me. --Imroy

f-number and aperture diameter

I have edited the article to remove the common misconception that the f-number is equal to the ratio of the focal length to the aperture diameter. It is not. The f-number is equal to the ratio of the focal length to the diameter of the entrance pupil of the lens. The latter is proportional to the diameter of the aperture. It is true that doubling the f-number halves the diameter of the aperture but it is not true that the aperture diameter is equal to the focal length divided by the f-number.--Srleffler 04:33, 14 February 2006 (UTC)

Is it science or technology?

I think the name of this page is a bit controversial. Though the subject matter is about scientific issues of photography, it is not forming a branch of science. The name of the page may imply that there exists such a branch. It is important to note that the photography technology does not tend to discover new rules or establish new theories (as what usually science does), instead it is using the current state of different sciences like physics, chemistry, etc to make better products and develop more convenient techniques. So I wouldn't call that the science of photography. --Neshatian 14:56, 21 February 2006 (UTC)

I would like to respectfully offer a second opinion.

I think the name is actually very good. Every aspect of photography has a huge body of science behind it. Photography could be said to be a blend of optics - chemistry - digital image capture - digital image processing - mechanical engineering - all sciences, or technologies so based on science, that no explanation of photography's physical aspects can take place without touching on some aspect of science.

I think the title implies that the article relates to the science and technology underlaying photography.

While photograpy is not a major branch of science such as physics, chemistry or astronomy, advances in photography have been a continuing area of current research for something like a century. Had photography not existed, I would guess much current knowledge in optics and chemistry would not exist. 1p2o3i 17:59, 4 September 2006 (UTC)

I might suggest Photographic Science? And/or a collaboration/merge with Imaging Science? Da5nsy (talk) 19:07, 20 March 2013 (UTC)

I'd like to echo the idea that this is related to imaging science. There have been many huge advances in the automated processing of images both in-camera and post-production. Some of these relate to the production of the final image, but many are significant in its retrieval from depositories. For example, facial recognition by Google Search. This is all an aspect of photographic technology. Ursus-deningeri2 (talk) 11:57, 28 August 2020 (UTC)

Discussion on wrong page?

I'm totally new to this editing and discussion process and the conventions of wikipedia, but the article itself seems to have discussion items on it that would properly belong here on the discussion page. 16:45 Sept 3 2006

Photography in general, or filmmaking?

The boxed header at the top of this discussion page which contains the words, "This article is part of Wikipedia:WikiProject Filmmaking....", suggests this article relates exclusively to motion picture filmmaking. However the title" Science of Photography" would suggest a much broader purpose. A reader would reasonably conclude the article pertains to the science of all photographic imaging; still; moving; film based; digital... 16:54 Sept 3 2006

Reciprocity: failure

The section on reciprocity, which derives from the original contribution of an anonymous editor in Sept. 2005, is pretty much a failure, and all wrong. The linked main article is more correct. I may work on fixing it, or may just remove it and direct to the other article. Film speed is really not part of the concept; this statement is bogus: "Halving the amount light exposing the film can be achieved...by...decreasing the film speed by one stop." Dicklyon 20:36, 17 January 2007 (UTC)

Cleanup, revert, plagiarism

I reverted back to the edits I had made earlier due to the claim of plagiarism in the intro. Plagiarism is the practice of claiming, or implying, original authorship or incorporating material from someone else's written or creative work, in whole or in part, into ones own without adequate acknowledgment. The intro I used was from Photography.com but was properly cited. Nonetheless, I re-wrote the intro and cited it again. I also did a lot of cleanup that I did not to be all for not. Hit me up with any comments or re-write the intro if still does not feel suitable. -Barkeep 13:09, 22 May 2007 (UTC) Talk

Plagiarism was the wrong word, it was copyright infringement. And it doesn't matter if the intro was cited. Unless the material had a license compatible with the GNU FDL that Wikipedia uses, or you had the permission of photography.com, that was still copyright infringement. No amount of credit or attribution can make it ok. It's as simple as that. --Imroy 13:34, 22 May 2007 (UTC)

Doesn't plagiarism mean unauthorized copying? Whatever... copyright violation is perhaps more precise here. Dicklyon 20:42, 22 May 2007 (UTC)

Oh, I should also mention that I thought it was lazy of Dicklyon to revert all of your edit when it was just the intro that was at issue. Doing a partial revert takes a little more time, but usually isn't that difficult. I assume there isn't a problem with the rest of your extensive edit. --Imroy 13:43, 22 May 2007 (UTC)

Lazy, yes. But if a large chunk of an edit is plagiarized, it's not my job to check the other parts. I assume it's all worth a revert, and not much more. Dicklyon 20:42, 22 May 2007 (UTC)

Silver-based Photography

I wonder whether this article is in danger of being superseded by technology and thus needing a major re-write or re-structuring. Digital photography has de-facto taken over from silver-based photography amongst amateurs and professionals and I doubt whether an article with the generic title "Science of Photography" but sole reference to traditional, silver-based processes does justice to state of the art photographic technology.--Rbudegb (talk) 12:37, 1 March 2009 (UTC)

Digital photography changes very little with regards to the science of its operation. Just looking at the sections of the article:

1. I would imagine that digital sensors suffer from reciprocity law failure too
2. Digital photography uses lenses
3. Digital photography suffers from motion blur
4. Digital cameras must still focus the image
5. Digital cameras still suffer from various forms of aberration in the lenses
6. Digital photography is not concerned with film grain resolution
7. Digital cameras may have problems with the diffraction limit of their lenses, especially the compacts
8. Digital sensors contribute to noise

So most of this article applies equally to both film and digital photography and also mentions some of the differences e.g with respect to grain vs noise. Please explain how simply replacing film with a digital sensor somehow "supersedes" all of the basic principles of physics that applies to both? --Imroy (talk) 13:56, 1 March 2009 (UTC)

I agree with you in that the basic laws of Physics aren't suddenly "superseded". However, I beg to differ in terms of the detail: every professional photographer will tell you that digital photography is a game changer and most aspects of the photographic process are effected. At the very least it merits equal mention to silver-based processes. My observation is that perhaps in its current guise, this article conveys a mis-leading and increasingly out-dated image as though silver-based capture is still the main technology.I'm happy to suggest changes. --Rbudegb (talk) 14:29, 1 March 2009 (UTC)

If you agree that the physics don't change with digital capture, then just what are you complaining about? This is the science of photography article, after all. From a quick search through the article, there is only one place where the word 'film' is not immediately followed (or preceded in one case) by the digital equivalent (excluding the 'film grain' section). The use of 'CCD' should be changed to something more generic because many cameras now use CMOS or other sensors. But I digress.

You speak of "equal mention" and that the article "conveys a mis-leading and increasingly out-dated image". These sound like appeals to emotion to me. So please explain what you want to do. Or just do it, if it's not too large a change. --Imroy (talk) 09:23, 3 March 2009 (UTC)

Imroy, you're absolutely right; I should put my money where my mouth is so to say. But I'd like to make some suggestions to you and other editors first since you've been honing this article for some time and I've only just barged in.

1) in the opening paragraph I would drop the "such as Chemistry and Physics" since Chemistry evokes film and wet-lab processes more than anything else - or re-word it.

2) in the "reciprocity" section you refer to "film-speed" which could perhaps be changed to "ISO setting". However, there seems to be consensus that CCDs or CMOSs don't suffer from "reciprocity failure" like the photographic material this sections refers to (Schwarzschild -effect). They do suffer from shifting signal/noise ratios in that the quality of the data decreases in extreme low-light conditions - but that is different to the increasing lag or de-coupling and colourshift incurred with Schwarzschild.

3) The "Film Grain" section is, strictly speaking superfluous unless it is set in an historic framework.

4) The "Noise" section needs expanding or re-editing with the subsequent sections into "digital capture" or similar to elucidate how different light sensitive arrays work (CCDs, CMOSs, PMTs) and what factors shift the signal / noise ratio.

That's it for now - best regards --Rbudegb (talk) 21:19, 4 March 2009 (UTC)

Where is this consensus that image sensors don't suffer reciprocity failure? I always teach that they do, though it's of a very different sort than what you get with film. The film grain and noise sections should be merged, as grains are the primary source of what's essentially "shot noise" in film. Dicklyon (talk) 07:08, 5 March 2009 (UTC)

Hi, have a look at this: http://www.astropix.com/HTML/I_ASTROP/FILM_DIG.HTM It's a site that is devoted to Astrophotography, ie. a discipline which is ideal for examining reciprocity failure due to the long exposures involved. If you hover over each picture with your cursor, you see the comparison between film and digital. The accompanying text explains what's going on. BTW, I have no connection or conflict of interest with that site, other than that I found it illustrated our debate quite succinctly. --Rbudegb (talk) 20:10, 5 March 2009 (UTC)

What debate is that? I admit that it is not an uncommon claim to say that digital sensors have no reciprocity failure. I understand very well why they say it, and for the cooled sensors they use in astrophotography, it's pretty much true. But if you ask, in general, can the sensor capture the same qualilty image with half as much light and twice the exposure time, the answer is no, when the exposure time is so long that dark current is significant. For many consumer cameras, which aren't exactly cold inside, this limit can come in around 1 to 10 seconds. It's not the same kind of reciprocity failure as film has, but has essentially the same effect, of requiring more intensity than reciprocal with exposure time to get a given image quality. You find statements like "Note: Reciprocity failure does not affect digital cameras, although long exposure times will produce excess noise" and "With long shutter speeds, many digital cameras do have a well-known problem, although it is not called reciprocity failure" that both deny and confirm the problem. Whatever you call it, the concept of reciprocity breaks down at long exposure times. Dicklyon (talk) 03:57, 6 March 2009 (UTC)

Here is a useful description of what's going on. And this one says "something equivalent to reciprocity failure is present. The dark current...". These give you some idea what I mean when I teach against the idea that digital does not have reciprocity failure. Dicklyon (talk) 04:09, 6 March 2009 (UTC)

It seems to me we're talking about two entirely different properties: Schwarzschild (colour-shifts and changes in contrast) occurring in photographic emulsion at extremely long, low-light or extremely short high-intensity exposures on the one hand and deteriorating signal/noise ratios in digital devices in extreme low light conditions on the other. I guess we can argue until the cows come home whether indeed both constitute reciprocity failure. My main point is that the article doesn't make it clear enough that digital differs considerable from silver-halide capture: there is no equivalent failure to Schwarzschild in digital. CCD and CMOS technology has improved in leaps and bounds over the past 10 years to the point that you can use digital in very long exposures for Astrophotography without cooling your sensors (check the capture data in the link I posted before) - if "dark-current" - as per your link to the 1973 publication - is the main cause of reciprocity failure in digital at ultra long exposures I would consider that a largely academic issue - whereas reciprocity failure in film is not - it is still within the experience of the average amateur and professional (studio flash!) photographer. I guess we have to agree to disagree and leave the article as is. Here is a link to a site that may interest you: http://www.clarkvision.com/imagedetail/digital.sensor.performance.summary/index.html All the best. --Rbudegb (talk) 01:12, 7 March 2009 (UTC)

From the point of view of the astrophotographer, both effects are "deteriorating signal/noise ratios in extreme low light conditions," and both are also "colour-shifts and changes in contrast occurring at extremely long, low-light exposure." You are right that they are different, but to this level of description they are the same. If you think of them both as "leakage" phenomena, they differ in that film leaks toward dark and digital detectors leak toward light. I agree it's a good idea to compare and constrast digital and film; I just don't agree that saying digital is not subject to reciprocity failure should be a part of such a contrast. And I don't see why you'd call the digital case's behavior "academic"; it's very important, especially to the astrophotographer, who must decide how much to cool the sensor to reduce the effect enough for his observing conditions. And to the ordinary consumer DSLR shoot who wants to do night shots, comparing dark leakage of different cameras is an important consideration. Some are better than others, but leakage even in ideal pure silicon is non-trivial. But nobody is suggesting leaving the article as it is.

The Clarkvision page is interesting, but not entirely correct. For example in this bit:

Read noise dominates the signal-to-noise ratio of the lowest signals for short exposures of less than a few seconds to a minute or so. For longer exposures, thermal noise usually becomes a factor. Thermal noise increases with temperature, as well as exposure time. Thermal noise results from noise in dark current, and the noise value is the square root of the number of dark-current generated electrons.

He is confusing thermal noise with the noise of dark current; the latter does depend on temperature, but it's not what's called thermal noise. Thermal noise is part of the read noise, and can be made quite small in modern well-designed sensors. And his statement that "the noise value is the square root of the number of dark-current generated electrons" is really just a lower bound on the standard deviation; it will be worse if the dark current is not accurately estimated and subtracted. If a single well-matched dark frame is subtracted, for example, it will be greater by a factor of square root of two. If the temperature drifts between the image frame and the dark frame, or if dark frame subtraction is not done, it will be much worse. But whatever it is, it limits the range of exposure time over which you can count on reciprocity to give you increased SNR. Dicklyon (talk) 08:05, 7 March 2009 (UTC)