Editing Camera obscura (section)

===1000 to 1400: Optical and astronomical tool, entertainment===
[[File:Light behaviour through pinhole.svg|thumb|A diagram depicting [[Ibn al-Haytham]]'s observations of light's behaviour through a pinhole]]
[[Image:Pinhole-camera.svg|right|thumb|[[Pinhole camera]]. Light enters a dark box through a small hole and creates an inverted image on the wall opposite the hole.<ref name='physics_worldview'>{{cite book|author1-link=Larry D. Kirkpatrick | last1 = Kirkpatrick | first1 = Larry D. | last2 = Francis | first2 = Gregory E. | title = Physics: A World View | chapter = Light | edition = 6 | publisher = Thomson Brooks/Cole | year = 2007 | location = Belmont, California | pages = 339 | isbn = 978-0-495-01088-3}}</ref>]]

Middle Eastern [[physicist]] [[Ibn al-Haytham]] (known in the West by the Latinised Alhazen) (965–1040) extensively studied the ''camera obscura'' phenomenon in the early 11th century.

In his treatise "On the shape of the eclipse" he provided the first experimental and mathematical analysis of the phenomenon.<ref>{{Cite book|title=A Critical Edition of Ibn al-Haytham's On the Shape of the Eclipse. The First Experimental Study of the Camera Obscura|last=Raynaud|first=Dominique|publisher=Springer International|year=2016|location=New York}}</ref><ref>{{cite book|url=https://monoskop.org/images/7/70/Needham_Joseph_Science_and_Civilisation_in_China_Vol_4-1_Physics_and_Physical_Technology_Physics.pdf|title=Science and Civilization in China, vol. IV, part 1: Physics and Physical Technology|last=Needham|first=Joseph|access-date=5 September 2016|archive-url=https://web.archive.org/web/20170703010030/http://monoskop.org/images/7/70/Needham_Joseph_Science_and_Civilisation_in_China_Vol_4-1_Physics_and_Physical_Technology_Physics.pdf|archive-date=3 July 2017|url-status=dead|page=98|quote=it seems that, like Shen Kua, he had predecessors in its study, since he did not claim it as any new finding of his own. But his treatment of it was competently geometrical and quantitative for the first time.}}</ref> 
He understood the relationship between the [[Focus (optics)|focal point]] and the pinhole.<ref>{{cite book|url=https://monoskop.org/images/7/70/Needham_Joseph_Science_and_Civilisation_in_China_Vol_4-1_Physics_and_Physical_Technology_Physics.pdf|title=Science and Civilization in China, vol. IV, part 1: Physics and Physical Technology|last=Needham|first=Joseph|access-date=5 September 2016|archive-url=https://web.archive.org/web/20170703010030/http://monoskop.org/images/7/70/Needham_Joseph_Science_and_Civilisation_in_China_Vol_4-1_Physics_and_Physical_Technology_Physics.pdf|archive-date=3 July 2017|url-status=dead|page=99|quote=The genius of Shen Kua's insight into the relation of focal point and pinhole can better be appreciated when we read in Singer that this was first understood in Europe by Leonardo da Vinci (+ 1452 to + 1519), almost five hundred years later. A diagram showing the relation occurs in the ''Codice Atlantico'', Leonardo thought that the lens of the eye reversed the pinhole effect, so that the image did not appear inverted on the retina; though in fact it does. Actually, the analogy of focal-point and pin-point must have been understood by Ibn al-Haitham, who died just about the time when Shen Kua was born.}}</ref>

{{blockquote|The image of the sun at the time of the eclipse, unless it is total, demonstrates that when its light passes through a narrow, round hole and is cast on a plane opposite to the hole it takes on the form of a moon-sickle. The image of the sun shows this peculiarity only when the hole is very small. When the hole is enlarged, the picture changes, and the change increases with the added width. When the aperture is very wide, the sickle-form image will disappear, and the light will appear round when the hole is round, square if the hole is square, and if the shape of the opening is irregular, the light on the wall will take on this shape, provided that the hole is wide and the plane on which it is thrown is parallel to it.|sign=|source=}}

In his ''[[Book of Optics]]'' (circa 1027), Ibn al-Haytham explained that rays of light travel in straight lines and are distinguished by the body that reflected the rays, writing:<ref>A. Mark Smith, ed. & trans., “Alhacen's Theory of Visual Perception: A Critical Edition, with English Translation and Commentary, of the First Three Books of Alhacen's ''De Aspectibus'', the Medieval Latin Version of Ibn Al-Haytham's ''Kitāb Al-Manāẓir'',” ''Transactions of the American Philosophical Society'', 91, [https://www.jstor.org/stable/3657358 4] {{Webarchive|url=https://web.archive.org/web/20180721014319/https://www.jstor.org/stable/3657358 |date=21 July 2018 }}–[https://www.jstor.org/stable/3657357 5] {{Webarchive|url=https://web.archive.org/web/20190819120246/https://www.jstor.org/stable/3657357 |date=19 August 2019 }} (2001): i–clxxxi, 1–337, 339–819 at 379, paragraph 6.85.</ref>
{{blockquote|Evidence that light and color do not mingle in air or (other) transparent bodies is (found in) the fact that, when several candles are at various distinct locations in the same area, and when they all face an aperture that opens into a dark recess, and when there is a white wall or (other white) opaque body in the dark recess facing that aperture, the (individual) lights of those candles appear individually upon that body or wall according to the number of those candles; and each of those lights (spots of light) appears directly opposite one (particular) candle along a straight line passing through that window. Moreover, if one candle is shielded, only the light opposite that candle is extinguished, but if the shielding object is lifted, the light will return.|sign=|source=}}

Latin translations of the ''Book of Optics'' from about 1200 onward seemed very influential in Europe. Among those Ibn al-Haytham is thought to have inspired are [[Witelo]], [[John Peckham]], [[Roger Bacon]], [[Leonardo da Vinci]], [[René Descartes]] and [[Johannes Kepler]].<ref>{{cite book|title=Global History of Philosophy: The Period of scholasticism (part one)|last=Plott|first=John C.|page=460|year=1984|publisher=Motilal Banarsidass Publ. |url=https://books.google.com/books?id=ErMRGiNcxJIC&q=euclid+inverted+image&pg=PA460|isbn=9780895816788|access-date=9 November 2020|archive-date=10 November 2023|archive-url=https://web.archive.org/web/20231110061753/https://books.google.com/books?id=ErMRGiNcxJIC&q=euclid+inverted+image&pg=PA460#v=snippet&q=euclid%20inverted%20image&f=false|url-status=live}}</ref> However, ''On the shape of the eclipse'' remained exclusively available in Arabic until the 20th century and no comparable explanation was found in Europe before Kepler addressed it. It were actually al-Kindi's work and especially the widely circulated pseudo-[[Euclid]]ean ''De Speculis'' that were cited by the early scholars who were interested in pinhole images.<ref name =lindberg/>

In his 1088 book, ''[[Dream Pool Essays]]'', the [[Song dynasty]] Chinese scientist [[Shen Kuo]] (1031–1095) compared the focal point of a concave burning-mirror and the "collecting" hole of ''camera obscura'' phenomena to an oar in a rowlock to explain how the images were inverted:<ref>{{cite book|last=Needham|first=Joseph|title=Science and Civilization in China, vol. IV, part 1: Physics and Physical Technology|url=https://monoskop.org/images/7/70/Needham_Joseph_Science_and_Civilisation_in_China_Vol_4-1_Physics_and_Physical_Technology_Physics.pdf|access-date=5 September 2016|archive-url=https://web.archive.org/web/20170703010030/https://monoskop.org/images/7/70/Needham_Joseph_Science_and_Civilisation_in_China_Vol_4-1_Physics_and_Physical_Technology_Physics.pdf|archive-date=3 July 2017|pages=97–98|url-status=dead}}</ref>

{{blockquote|"When a bird flies in the air, its shadow moves along the ground in the same direction. But if its image is collected (''shu'')(like a belt being tightened) through a small hole in a window, then the shadow moves in the direction opposite of that of the bird.[...] This is the same principle as the burning-mirror. Such a mirror has a concave surface, and reflects a finger to give an upright image if the object is very near, but if the finger moves farther and farther away it reaches a point where the image disappears and after that the image appears inverted. Thus the point where the image disappears is like the pinhole of the window. So also the oar is fixed at the rowlock somewhere at its middle part, constituting, when it is moved, a sort of 'waist' and the handle of the oar is always in the position inverse to the end (which is in the water)."}}

Shen Kuo also responded to a statement of [[Duan Chengshi]] in ''[[Miscellaneous Morsels from Youyang]]'' written in about 840 that the inverted image of a [[Chinese pagoda]] tower beside a seashore, was inverted because it was reflected by the sea: "This is nonsense. It is a normal principle that the image is inverted after passing through the small hole."<ref name="needham4 98"/>

English statesman and [[scholasticism|scholastic philosopher]] [[Robert Grosseteste]] (c. 1175 – 9 October 1253) was one of the earliest Europeans who commented on the ''camera obscura''.<ref>{{Cite journal|url=https://doi.org/10.1007/BF00327235|title=A reconsideration of Roger Bacon's theory of pinhole images|first=David C.|last=Lindberg|date=1 January 1970|journal=Archive for History of Exact Sciences|volume=6|issue=3|pages=214–223|via=Springer Link|doi=10.1007/BF00327235|pmid=11615487|s2cid=45315239|access-date=9 December 2021|archive-date=10 November 2023|archive-url=https://web.archive.org/web/20231110061744/https://link.springer.com/article/10.1007/BF00327235|url-status=live}}</ref>

English philosopher and Franciscan friar [[Roger Bacon]] (c. 1219/20 – c. 1292) falsely stated in his ''De Multiplicatione Specerium'' (1267) that an image projected through a square aperture was round because light would travel in spherical waves and therefore assumed its natural shape after passing through a hole. He is also credited with a manuscript that advised to study solar eclipses safely by observing the rays passing through some round hole and studying the spot of light they form on a surface.<ref name=Mannoni1>{{cite book|url=https://books.google.com/books?id=t_cSAQAAMAAJ|last=Mannoni|first=Laurent|title=The great art of light and shadow|year=2000|pages=5|publisher=University of Exeter Press |isbn=9780859895675|access-date=16 September 2020|archive-date=10 November 2023|archive-url=https://web.archive.org/web/20231110061750/https://books.google.com/books?id=t_cSAQAAMAAJ|url-status=live}}</ref>

Polish friar, theologian, physicist, mathematician and natural philosopher [[Vitello]] wrote about the ''camera obscura'' in his influential treatise ''Perspectiva'' (circa 1270–1278), which was largely based on Ibn al-Haytham's work.

English archbishop and scholar [[John Peckham]] (circa 1230 – 1292) wrote about the ''camera obscura'' in his ''Tractatus de Perspectiva'' (circa 1269–1277) and ''Perspectiva communis'' (circa 1277–79), falsely arguing that light gradually forms the circular shape after passing through the aperture.<ref>{{cite book|title=Tractatus de perspectiva|last1=Lindberg|first1=David C.|last2=Pecham|first2=John|year=1972|url=https://books.google.com/books?id=UytDAAAAIAAJ&q=camera&pg=PA15|access-date=9 November 2020|archive-date=10 November 2023|archive-url=https://web.archive.org/web/20231110061751/https://books.google.com/books?id=UytDAAAAIAAJ&q=camera&pg=PA15#v=snippet&q=camera&f=false|url-status=live}}</ref> His writings were influenced by Bacon.

At the end of the 13th century, [[Arnaldus de Villa Nova]] is credited with using a ''camera obscura'' to project live performances for entertainment.<ref>{{cite web|last=Burns|first=Paul T.|title=The History of the Discovery of Cinematography|url=http://www.precinemahistory.net/900.htm |access-date=4 January 2014 |archive-url=https://web.archive.org/web/20131231080921/http://www.precinemahistory.net/900.htm |archive-date=31 December 2013}}</ref><ref>{{cite web|last=Smith|first=Roger|title=A Look into Camera Obscuras|url=http://www.camera-obscura.org.uk/Camera_Obscura/Timeline.html|access-date=23 October 2014|archive-date=29 October 2014|archive-url=https://web.archive.org/web/20141029030133/http://www.camera-obscura.org.uk/Camera_Obscura/Timeline.html|url-status=live}}</ref>

French astronomer Guillaume de Saint-Cloud suggested in his 1292 work ''Almanach Planetarum'' that the eccentricity of the Sun could be determined with the ''camera obscura'' from the inverse proportion between the distances and the apparent solar diameters at apogee and perigee.<ref>{{cite book|first=J.L.|last=Mancha|title=Studies in Medieval Astronomy and Optics|pages=275–297|url=https://books.google.com/books?id=02KQgQNL-P4C&q=%22william+of+saint-cloud%22+camera&pg=PA37|isbn=9780860789963|year=2006|publisher=Ashgate Publishing |access-date=9 November 2020|archive-date=10 November 2023|archive-url=https://web.archive.org/web/20231110061751/https://books.google.com/books?id=02KQgQNL-P4C&q=%22william+of+saint-cloud%22+camera&pg=PA37#v=snippet&q=%22william%20of%20saint-cloud%22%20camera&f=false|url-status=live}}</ref>

[[Kamāl al-Dīn al-Fārisī]] (1267–1319) described in his 1309 work ''Kitab Tanqih al-Manazir'' (''The Revision of the Optics'') how he experimented with a glass sphere filled with water in a ''camera obscura'' with a controlled aperture and found that the colors of the rainbow are phenomena of the decomposition of light.<ref>Nader El-Bizri, "Optics", in ''Medieval Islamic Civilization: An Encyclopedia'', ed. Josef W. Meri (New York – London: Routledge, 2005), Vol. II, pp. 578–580</ref><ref>Nader El-Bizri, "Al-Farisi, Kamal al-Din," in ''The Biographical Encyclopaedia of Islamic Philosophy'', ed. Oliver Leaman (London – New York: Thoemmes Continuum, 2006), Vol. I, pp. 131–135</ref>

French Jewish philosopher, mathematician, physicist and astronomer/astrologer [[Gersonides|Levi ben Gershon]] (1288–1344) (also known as Gersonides or Leo de Balneolis) made several astronomical observations using a ''camera obscura'' with a [[Jacob's staff]], describing methods to measure the angular diameters of the Sun, the Moon and the bright planets Venus and Jupiter. He determined the eccentricity of the Sun based on his observations of the summer and winter solstices in 1334. Levi also noted how the size of the aperture determined the size of the projected image. He wrote about his findings in Hebrew in his treatise ''Sefer Milhamot Ha-Shem'' (''The Wars of the Lord'') Book V Chapters 5 and 9.<ref>{{cite book|title=The Astronomy of Levi ben Gerson|pages=140–143|last=Goldstein|first=Bernard R.|date=6 December 2012|publisher=Springer |isbn=9789401133425|url=https://books.google.com/books?id=ETOtBgAAQBAJ&pg=PA79|access-date=20 December 2019|archive-date=10 November 2023|archive-url=https://web.archive.org/web/20231110062242/https://books.google.com/books?id=ETOtBgAAQBAJ&pg=PA79#v=onepage&q&f=false|url-status=live}}</ref>