Talk:Camera obscura

Al-hazem
Could we suggest [it is indeed established] that creation of the camera obscura was accidental? I've seen descriptions concluding, from Al-Hazem's text, the dark room was known to him before he used it for the experiments on eclipse.

And as for the theory, the observation of the inverted image, there are also an account about a Chinese called Mo Ti and his observation of inverted image, a century before similar observations from Aristotle. (I donno a reference for this accounts yet)

It seems less of a [accidental] discovery, and more of a creativity.

Downtownee 10:22, 31 October 2006 (UTC)


 * If you look at Jagged 85's edits, he changes "persian scientist" to Iraqi and keeps pushing it. Obviously the previous edit of "dark pussy hole" is a troll, but I'm seriously doubting Jagged's NPOV stance or otherwise agenda free maintenance at this point.

Comparison link: http://en.wikipedia.org/w/index.php?title=Camera_obscura&diff=188751796&oldid=188031134

Did Iraq exist in Al-Hazem's time? Shouldn't it be Mesopotamia?

Apepper (talk) 07:49, 12 June 2008 (UTC) -

Lets stop the lying please: Lets face it... Scientists like Aristotle & Mo-Ti etc. have proven to have discussed the principle of light being projected from a hole onto a surface (possibly even in a dark room)

Ibn al-Hatham (a.k.a Alhazen) was the first person (with proof) to have created the 'camera obscura' and used it for experiments, and explained the inversion of light.

Ok maybe you don't like him. But its the truth, you should provide an accurate story & not hide anything. If you want to do the right thing, and be respected & trusted as editors. Include him OR include the person who created one before him.


 * 1) http://www.bbc.co.uk/dna/h2g2/A2875430
 * 2) http://en.wikipedia.org/wiki/Alhazen#cite_note-Wade-44
 * 3) (Kelley, Milone & Aveni 2005):
 * "The first clear description of the device appears in the Book of Optics of Alhazen."


 * 1) ^ a b (Wade & Finger 2001):
 * "The principles of the camera obscura first began to be correctly analysed in the eleventh century, when they were outlined by Ibn al-Haytham." — Preceding unsigned comment added by 92.4.221.62 (talk) 10:55, 20 September 2011 (UTC)

Calling someone who lived in that of the world in that time an "Iraqi" is simply ludicrous. It is a like saying that Hiawatha was an American and that he lived in the U.S.A. Or that Czar Nicholas lived in the U.S.S.R. — Preceding unsigned comment added by 68.71.8.84 (talk) 20:41, 14 July 2011 (UTC)


 * Al-Kindi also studied Camera Obscura but with an extramissionist theory. This characterize the camera obscura interpretation of Al-Kindi very different from the modern interpretation. Alhazen reached an interpretation that is very similar to the modern version of geometrical optics. Al-Kindi was based on Euclids. He essentially added arguments for rectilinear propagation of light by using CAmera obscura, whereas EUuclids postulated rectilinear propagation. One important difference between Euclids and Al-Kindi is the rejection of discrete rays by AL-Kindi which he substitute by a field of view like Ptolemy. All this ideas are in the history of optics of Darrigol (https://books.google.com.br/books/about/A_History_of_Optics_from_Greek_Antiquity.html?id=Ye_1AAAAQBAJ&redir_esc=y).
 * Manouchk (talk) 20:01, 8 April 2024 (UTC)

The invention/creation of the Camera Oscura

 * Having gone over some books and sources over the Internet, it is important we mention Mo-Ti's and Aristotle's discovery of the camera oscura principle first, which dates prior to Al-Hasan's assembly of the princicples. This will help this article become more factual, detailed and useful to Wikipedia users. I will soon provide some links and ISBNs for sources we could use to accurately describe the discovery and creation with fair credits to the concerned people. Here is an extract:


 * "''The earliest mention of this type of device was by the Chinese philosopher Mo-Ti (5th century BC). He formally recorded the creation of an inverted image formed by light rays passing through a pinhole into a darkened room. He called this darkened room a "collecting place" or the "locked treasure room."


 * Aristotle (384-322 BC) understood the optical principle of the camera obscura. He viewed the crescent shape of a partially eclipsed sun projected on the ground through the holes in a sieve, and the gaps between leaves of a plane tree.


 * The Islamic scholar and scientist Alhazen (Abu Ali al-Hasan Ibn al-Haitham) (c.965 - 1039) gave a full account of the principle including experiments with five lanterns outside a room with a small hole.'' "


 * link http://brightbytes.com/cosite/what.html


 * If I don't hear from anyone who is willing to collaborate, I will run through with you guys the proposed addition and then proceed to add the amendments myself. --Sina7 (Signature added by Downtownee)


 * Please do. My previous note concerned this matter. I'm delighted someone is going to take it over. I put my note before yours for the sake of being chronologically ordered while having related notes together. -- Downtownee 07:53, 3 October 2007 (UTC)

Seville
I believe there is one in seville, spain that gives a view of most of the city and all of the expo '92, it is called, "torre tavira". I don't dare edit the article but if anyone can verify then it should be added to the list of locations. 65.184.41.200 02:59, 3 October 2007 (UTC)

Latin word
Since the correct italian spelling is Camera oscura (without b), I'd redirect it to the correct spelling, unless in english it is used instead with the current spelling. In this case I'd add a redirect from Camera oscura. --Gianfranco

"Camera obscura" is correct in English. It's Latin, not Italian. --Zundark, Tuesday, April 9, 2002


 * Just a note: English is Germanic. Italian, is, a Latin language. --Downtownee 10:29, 4 February 2007 (UTC)

More Camera Obscura
There are two other famous Camera obscuras - one in Wales and one in Santa Monica, California. And in the movie - A Matter of Life and Death Middle Street, Shere, Surrey, England, UK is the village seen through camera obscura.

Old painting masters
Wasn't there some consperacy theory that the old masters used these to make their paintings?
 * Yes, see David Hockney. It needs adding to this article. Justinc 22:28, 8 Apr 2005 (UTC)


 * Yes there were. It is not considered a conspiracy though. One of the first uses of the new invention, photgraphy, esp. during 1850s, was its assistance to painters. There were a debate on if photography is indeed a distict form of art, and many of the first photogrpahers were either painters themselves or were commissioned to make up very complicated images used by painting masters as "sketches". One of these photographers was O. G. Rejlander. Also have a look at Henry P. Robinson, who held a view of the photography must follow aesthetic and scenery rules of the contemporary painting. Plus Hockney is not an "old" master! --Downtownee 10:29, 4 February 2007 (UTC)

Correct the misspelling
Strange, the main page has the incorrect spelling "Camera Onscura" but when I go to the edit section the correct "Camera obscura" is listed...oh well. I guess I can't change it. - John

Plural form
'Cameras obscura' is the proper plural form, not 'camera obscuras'. I've corrected the article. Future editors should keep this in mind. Kent Wang 18:30, 11 July 2005 (UTC)


 * This is not even correctly pedantic. Common usage has the plural 'camera obscuras', which is easily good enough. The correct plural form, never used by anyone at all, is 'cameras obscurae'.


 * Try camerae obscurae for the actual latin plural. "Cameras obscura" and "Camera obscuras" kind of make sense as an english plural, but mixing english and latin plural forms in "cameras obscurae" is just strange. FiggyBee 09:39, 13 November 2006 (UTC)


 * The only plural form that appears in the OED is "camera obscuras", from Charles Hutton's Mathematical and Philosophical Dictionary of 1796.   -- Dominus 15:00, 7 February 2007 (UTC)


 * Google book search finds 26 citations for "cameras obscura" and 262 for "camera obscuras". -- Dominus 15:00, 7 February 2007 (UTC)


 * Of eight dictionaries I consulted, five were silent. OED, American Heritage 4, and Webster’s 3rd give “camera obscuras.” There really is no reason for “cameras obscura.” Maybe if the phrase came from French, such as attorney general, then maybe there would be an argument. Maybe. But it didn’t. It came from Latin. So you either treat it as a compound English word (as all the dictionaries do) and add an “s” at the end, or you use the Latin and write “camerae obscurae.” John P. McCaskey (talk) 18:03, 8 July 2014 (UTC)


 * It's an English-language phrase based upon Latin. Still, it's English, and it follows normal English pluralization. The ancient Romans never had these darkened rooms, so they never wrote this phrase down, nor probably ever said it either. BeenAroundAWhile (talk) 19:11, 30 August 2016 (UTC)


 * Oh, good. One never knows when one'll be called on to refer to more than one of these at a time, does one? It could happen at any moment. Perhaps it already has! No, I would've remembered something that exciting. Still, though. – AndyFielding (talk) 08:00, 22 May 2021 (UTC)

Vermeer
The article says there is considerable controversy over whether Vermeer and others used the camera obscura. But last night I saw a documentary on the BBC (Light Fantastic) where it was said that a precise date can be given when Vermeer switched fully to the camera obscura. Now there were some inaccuracies in the documentary but those were simplifications for 'the less educated viewer', so to say. But saying one can pinpoint a date is something different. Anyone know more? DirkvdM 06:28, 25 August 2005 (UTC)
 * Rebecca Stefoff in The Camera notes Philip Steadman's detailed analysis and reconstruction of Vermeer's use of the camera obscura and that though some art historians still dispute his proofs, it is certain that Canaletto was admired for his skill in judiciously employing the device, and that there is no doubt that Joshua Reynolds made use of his, which was disguised as a book, despite his deprecation of it as an instrument of 'high art' in his' Discourses on painting and the fine arts : delivered at the Royal Academy  ~

Resolution
The article said that a pinhole gives low resolution, which can be solved by using a lens. I don't see how this influences resolution (it does influence light-sensitivity, though), so I removed that. Resolution is a matter of how fine the grain is in a photocamera. The equivalent in the camera obscura would be how accurate the artist is, I suppose. DirkvdM 06:58, 25 August 2005 (UTC)


 * A formula can be found at pinhole camera. Anyway, a pinhole for this use gives neither brightness nor resolution. Meggar 03:12, 11 January 2006 (UTC)


 * resolution is not just a term relevant to film grain. it refers to how well an image resolves at the VP. If you've ever tried making a pinhole camera, and have used a huge hole, you will know that the circle of confusion becomes so great that the image is comprised of large circles, it is then said to have poor resolution. DavidP

removed this etymology
also known in Arabic as “qamara”, hence Latin camera

Since it isn't - "camera" is Latin for "chamber", and was long before the invention of the camera obscura. (See for example) FiggyBee 09:22, 13 November 2006 (UTC)

"A Muslim named Abu Ali Al-Hasan Ibn al-Haitham"
Regarding the sentence "A Muslim named Abu Ali Al-Hasan Ibn al-Haitham (965-1039 CE), known in the West as Al-Hazen...", what relevance to the article is it that he was a Muslim? There are plenty of other people referenced in the article, and there is no mention of their choice of belief. For example, the following people are mentioned: Willett & Patteson, Leonardo da Vinci, Johann Zahn, Johannes Vermeer, Johannes Kepler, Robert Boyle, Robert Hooke, Paul Sandby, Canaletto, Joshua Reynolds, Louis Daguerre and William Fox Talbot. These people have not been introduced by referring to their personal beliefs, so why is there need to mention Abu Ali Al-Hasan Ibn al-Haitham's? --203.10.224.59 06:14, 8 May 2007 (UTC)


 * Muslim community, especially in Middle East as its origin, is intentionally and, through elementary education, unconsciously aware of a brotherhood among themselves called "umma." Hence many Muslims are used to indicate or show interest if someone is of their own religion. Your point, nevertheless, is right and it should be asked to be tolerated by Muslims if these kind of remarks are removed from the text. Downtownee 12:27, 11 May 2007 (UTC)

Serious Problems Regarding Abu Ali Al-Hasan Ibn al-Haitham
Whoever keeps adding/reverting the article should consider the following: Haitham was born in Cairo, not Iraq or Persia. He also is not the first person to make observations on this subject - The "inventors" are the Chinese, the Greeks furthered it, and the Copts, such as Haitham, contributed also. Haitham says himself that he did not invent this. There are plenty of other references on Wikipedia to preexisting camera obscura. —Preceding unsigned comment added by 12.150.11.25 (talk) 20:25, 8 November 2007 (UTC)


 * Not really. Every biography of Ibn al-Haytham clearly states that he was born in Basra and later worked in Cairo. Jagged 85 (talk) 09:46, 18 July 2008 (UTC)

Internal conflict
Hello,

I might be missing something here, but "The first mention and discovery of the principals behind camera obscura belong to Mozi (470 BCE to 390 BCE)" and then "A Persian (of Arab background) scientist named Abu Ali Al-Hasan Ibn al-Haitham, born in Basra (965-1039 [B]CE) [studied the phenomena/system] "

This would appear to indicate that al-Haitham had the first thing that might be called a camera obscura? At the least it jumps the timeline around a little. User A1 (talk) 08:44, 9 January 2008 (UTC)


 * What Mozi and Aristotle described were the principles of a pinhole camera. What Ibn al-Haytham described was a camera obscura ("dark chamber"). Jagged 85 (talk) 22:15, 3 February 2008 (UTC)


 * Jagged 85 clearly has an agenda here or knows nothing about photography. More to the point it's pretty gross you keep using the term "iraqi". I don't refer to Native American tribes which ones existed in the USA as "New Jerseyian". Since you're paying more attention to the wording "iraqi" then you are interested in reconciling the technological differences between the observations Aristotle made and Mozi I'm going to call you on bullshit. —Preceding unsigned comment added by 12.150.11.25 (talk) 21:22, 11 June 2008 (UTC)


 * Dude, I'm not the one who wrote this article. If you just came here to personally attack me, go to my talk page and do it. Anyway, I've recently updated the article to include all the different versions of the camera obscura, from the rudimentary version described by Aristotle to the complete modern version described by Alhazen. Jagged 85 (talk) 09:43, 18 July 2008 (UTC)

Photograph of camera obscura projection
Hi, I noticed that there is no picture which shows how the image of a Camera Obscura actually looks like. I just played with Commons and uploaded such a picture (http://commons.wikimedia.org/wiki/Image:Camera_obscura_example_picture.JPG). Since it surpasses my wiki skills to integrate it anyway, I leave it to you to decide whether this is a sensible addition. (You can say it sucks, and that it is not. That's ok :) ) —Preceding unsigned comment added by 78.53.146.235 (talk) 10:41, 29 October 2008 (UTC)

This article needs to be rewritten
The writing's terrible!--97.66.98.27 (talk) 23:51, 25 May 2009 (UTC)

Possibly Italian?
The caption of the 17th century drawing says it's "possibly Italian", but since the building is clearly the Florence Cathedral isn't it pretty obviously Italian? Pais (talk) 14:16, 31 August 2009 (UTC)

Improper Rendering in Firefox
The image http://en.wikipedia.org/wiki/File:Canaletto4fogli.jpg renders next to the TOC in IE, but overlaps it completely in Firefox. The image should probably not even be there in the first place, but on the right hand side of the article. I'd fix it but I don't know how to edit wikipedia, and don't have the time to learn right now. —Preceding unsigned comment added by 71.225.88.153 (talk) 15:05, 10 January 2010 (UTC)

Alhazen inventions are usefull for the world
world used Alhazen works not others, Alhazen created optic's theory in his book of optics. i knew the wrong concept of optic in europe that light come out from eyes that should be light come into eyes. many wrong theories in greek scientist. and i did not see chinese scientist before so why it appears now....we should not change histories right ? —Preceding unsigned comment added by Shatree (talk • contribs) 05:31, 4 February 2010 (UTC)

url redirect to disambiguation?
i don't know how to check the stats, but i'm betting the UK and US bands also get a pretty high number of views, so maybe the page for /Camera_Obscura could lead to a disambiguation page between the three? —Preceding unsigned comment added by 68.150.203.57 (talk) 08:48, 13 February 2010 (UTC)

Misusing of refs
is one of the main contributors to Wikipedia (over 67,000 edits; he's ranked 198 in the number of edits), and practically all of his edits have to do with Islamic science, technology and philosophy. This editor has persistently misused sources here over several years. This editor's contributions are always well provided with citations, but examination of these sources often reveals either a blatant misrepresentation of those sources or a selective interpretation, going beyond any reasonable interpretation of the authors' intent. Please see: Requests for comment/Jagged 85. That's an old and archived RfC. The point is still valid though, and his contribs need to be doublechecked. I searched the page history, and found 31 edits by Jagged 85 (for example, see this edits). Tobby72 (talk) 15:58, 14 June 2010 (UTC)

Dodgy para cut to talk
I've removed this:

Alhazen provided the first clear description and correct analysis of the device and for first describing how an image is formed in the eye using the camera obscura as an analogy.
 * While these earlier scholars described the effects of a single light passing through a pinhole, none of them suggested that what is being projected onto the screen is an image of everything on the other side of the aperture. Abu Ali Al-Hasan Ibn al-Haytham (965–1039 AD), known in the West as Alhacen or Alhazen, in his Book of Optics (1021), was the first to demonstrate this with his lamp experiment where several different light sources are arranged across a large area, and he was thus the first scientist to successfully project an entire image from outdoors onto a screen indoors with the camera obscura.

The assertion that "none of them suggested that what is being projected onto the screen is an image of everything on the other side of the aperture" is quite unbeleiveable in the light of "The Greek philosopher Aristotle (384 to 322 BCE) understood the optical principle of the pinhole camera. He viewed the crescent shape of a partially eclipsed sun projected on the ground through the holes in a sieve, and the gaps between leaves of a plane tree". I suspect (but haven't verified) that this is yet more Jaggedese William M. Connolley (talk) 10:04, 23 March 2011 (UTC)

Alhazen is Missing
As it currently stands, all mention of Alhazen has been eliminated from the article, except for a couple reference titles. If the article had once been too laudatory of Alhazen's contributions, it is now at the other extreme. Others provide evidence below that Alhazen's use of the camera obscura is a milestone in the history of science. The sentence, "The Song Dynasty Chinese scientist Shen Kuo (1031–1095) experimented with a camera obscura, and was the first to apply geometrical and quantitative attributes to it in his book of 1088 AD, the Dream Pool Essays" is false. Alhazen's Book of Optics is from 1021. I also suggest you use the latinized "Alhazen" in the article (and the talk) as that is how is referred to in his Wikipedia article. — Preceding unsigned comment added by McLir (talk • contribs) 13:40, 22 February 2012 (UTC)


 * Perhaps that's partly my fault. In this edit I took out an unsourced bit about Alhazen that had been stuck in at a bad place, with no support.  I'm certainly not against getting a good correct sourced history in there.  Maybe you can work on that.  Dicklyon (talk) 23:27, 22 February 2012 (UTC)

Other languages
There is an article about camera obscura on Chinese wiki, please also add it, thanks.

http://zh.wikipedia.org/wiki/%E6%9A%97%E7%AE%B1 — Preceding unsigned comment added by 112.118.41.91 (talk) 07:02, 23 November 2013 (UTC)

Mo Tze and Al-Hazen mentioned on Cosmos regarding the camera obscrura
(I didn't have a pen handy while watching the 5th episode of "Cosmos: A Spacetime Odyssey", "Hiding in the Light", but I believe the man's name might have been given as "Mo Tze" in the animation.) Anyway, some information about his his life and beliefs was presented in a very positive light. He was credited with developing the beginnings of the scientific method and demonstrating the camera obscura. The segment about Al-Hazen is even longer and of course the camera obscrura is discussed. I think he was referred to Arabic. If you missed this episode, it's being rebroadcast on the "National Geographic Channel" at 11P eastern tonight (right now!). Or you can watch the episode on the show's website for the next 97 days. http://www.cosmosontv.com/ Yours, Wordreader (talk) 03:01, 8 April 2014 (UTC)

Aristotle is misquoted - and according to a reliable source (NASA) he was not referring to the pinhole camera, but to the phenomenon of diffraction
Article text: ''The Greek philosopher Aristotle (384 to 322 BCE) understood the optical principle of the pinhole camera.[3] He viewed the crescent shape of a partially eclipsed sun projected on the ground through the holes in a sieve and through the gaps between the leaves of a plane tree. In the 4th century BCE, Aristotle noted that "sunlight travelling through small openings between the leaves of a tree, the holes of a sieve, the openings wickerwork, and even interlaced fingers will create circular patches of light on the ground."''

Correct quote: (many places on the net):

"Why is it that when the sun passes through quadri-laterals, as for instance in wickerwork, it does not produce a figure rectangular in shape but circular?" he wrote. "Why is it that an eclipse of the sun, if one looks at it through a sieve or through leaves, such as a plane-tree or other broadleaved tree, or if one joins the fingers of one hand over the fingers of the other, the rays are crescent-shaped where they reach the earth?"

For the answer suggested, see:   http://science.nasa.gov/science-news/science-at-nasa/2003/30may_solareclipse2/    RPSM (talk) 10:25, 18 September 2014 (UTC)


 * The holes in the wickerwork or sieve are the pinholes, each forming an image. The wording "... if one looks at it through ..." is suggestive of some other phenomenon, but the statement that "the rays are crescent-shaped where they reach the earth" makes it clear that projected images are the subject, not direct viewing through the apertures. My guess is that the original Greek for what is here rendered as "through" might more accurately be translated as "by means of" or the like. Being a NASA scientist is no guarantee of expertise in the nuances of ancient Greek. Diffraction would have played no essential role in forming the projected images described. 66.81.241.184 (talk) 02:57, 12 June 2016 (UTC)


 * To clarify my previous comment: the role of diffraction in forming a pinhole image is of negligible importance unless the pinhole is small enough that edge diffraction affects a significant percentage of the light passing through it. With a relatively large hole (as in an ancient sieve), the imaging can be explained solely by the fact that rays from the subject travel in straight lines (because they are not diffracted) from the subject through the hole and onto the projection surface. Aristotle's question can be answered without recourse to the phenomenon of diffraction: an image of the solar disk formed through a square hole will only appear round if the image of the Sun is sufficiently large in comparison to the correspondingly distant hole. Each point of the Sun is actually imaged as a square, but the size of each such square is constant regardless of the projection distance, while the image of the Sun as a whole becomes larger with increased distance. In other words, the image seen actually consists of numberless images of the square hole (or a square array of overlapping images of the Sun's disk, if you prefer) which are not individually discernible. But the image will be quite noticeably square if the projection surface is very near the same square hole and the image formed is therefore very small. 66.81.241.184 (talk) 04:13, 12 June 2016 (UTC)

Invented
I took out the assertion that Alhazen‎ invented the camera obscura. That turns out to be User:Jagged 85, and hence unreliable William M. Connolley (talk) 21:13, 4 January 2015 (UTC)


 * Hmm. The artcile could use some Brünofication still. Serten II (talk) 21:32, 6 January 2015 (UTC)

Aberystwyth
The camera obscura on Constitution Hill in Aberystwyth is open to the general public from 11 am to 4 pm every day. One of the largest in the world, it was built in 1880. Everybody got to be somewhere! (talk) 15:01, 22 May 2016 (UTC)

pinhole image projection direct viewing
Some readers come to WP seeking info about direct viewing of pinhole projected image, such as for eclipses. There are many related WP articles, perhaps most relevant Pinhole camera, but none that do a great job of discussing the subject. (Also, a good discussion might mention that with care and fiddling ordinary hand-held binoculars can do quite a good job of projecting a clear and sizable image onto a safe surface.)-71.174.177.142 (talk) 21:46, 21 August 2017 (UTC)
 * Pinhole camera
 * Camera obscura
 * Solar_eclipse
 * Pinhole (optics)
 * Pinhole camera model (Redirected from Pinhole projection)
 * Magic lantern

Viewed as a mirrored image or not?
It is stated now : "If the image is caught on a semi-transparent screen, it can be viewed from the back so that it is no longer reversed (but still upside-down)" I don't think that the part after "the back" is correct. (Or, have I missed a crucial element?)..

E.g. : - If I stand in a room and face the window and look outside I might see a red light to my left, a green light to my right, a yellow light at the top and an blue light at the bottom.

- if I now close the shutters and create a small hole I turn the room into a camera obscura

- If I now turn arround and face the wall opposite the widow I will still see the red light to my left, the green to my right, but the blue on top and the yellow below. (So, in this case I would see the image not as reversed, only upside down. )

- if the opposite wall would be of a semi transparent glass and I would view the image from behind the glass I would see the green light to my left, the red light to my right and the blue on top and the yellow below. (So, in this case I would see the image reversed and upside down. )

Only if I would place a mirror on the wall opposite the window in such a way that it would project the image on an other transparent glass and I would view that glass from behind I would see all the lights in the correct position.

Proposal for the text: "If the image is caught on a semi-transparent screen, it can be viewed from the back as a reversed and upside-down image. By placing a mirror between the hole/lens and the screen the image can by viewed in the correct orientation."

[Maybe even include my step-by-step example?] Vlaascho (talk) 09:47, 23 May 2020 (UTC)


 * If, in your example, you take a photograph of the projection from the front of the wall and turn it upright you'll have the red to the right, the green to the left, yellow at the top and blue at the bottom: a mirrored image. Maybe it's easier to imagine the effect with the image of a person raising one hand (a raised left hand would seem to be the person's right hand in the frontal view of the projected image).


 * I replaced the top image in the article with one that illustrates the reversal slightly better (the person sitting outside has the monument to his left, so in the projection it's on his right). I first found and used a version of a very similar image that is drawn much clearer, but the depiction of the person in the projection turned out to be wrong (the person is in the right place but with her hands in the wrong position). Somehow, most images of the principle don't really show the reversal at all and unfortunately several that did try to incorporate it failed to get the details right. I hope to find a clear and correct image sometime.


 * It's tricky to describe the reversal correctly, so there may be some confused or confusing lines in the article, but do you now agree with the line that you believed to be incorrect?Joortje1 (talk) 07:03, 24 May 2020 (UTC)

Pinhole images?
Back in 2016, in this edit, we took to equating "pinhole images" to the camera obscura. And before that it was already a "phenomenon". All the books I can find say that a camera obscura is the "dark room" in which the image is formed; the structure or apparatus, not the phenomenon, and not the image. Comments before I work on rewriting the lead accordingly? Dicklyon (talk) 22:26, 15 October 2020 (UTC)

I changed it. Comments? Dicklyon (talk) 17:14, 2 December 2020 (UTC)


 * I only noticed this question today. I believe it was problematic that the term "pinhole images" was removed from the lead, because its oft-repeated use in the rest of the text made much less sense without it. I hope my new addition to the text helps. Unfortunately, I have not yet found sources that are more useful (amongst all the clutter about photographic pinhole images and some other technical applications). There must be some citation-worthy texts that properly describe this physical phenomenon, but I gave up looking. From the refs that I did include, it must nonetheless be clear enough that "pinhole image" is the same as the principle of "camera obscura" and that these terms do get equated.Joortje1 (talk) 21:36, 16 September 2023 (UTC)

Use of language
This article repeatedly asserts that such-and-such a person (eg Roger Bacon) “falsely” argued for a particular proposition. Unless it is being suggested that the person deliberately argued a case that he knew to be wrong (in which case the assertion should be properly evidenced), the adverb “falsely” constitutes a misuse of the English language. It may be that the author is not a native English speaker, but a better choice would be “mistakenly” or “incorrectly”. Teagueqc (talk) 14:53, 28 March 2024 (UTC)