Editing Daguerreotype (section)

== ''Camera obscura'' ==
{{Main|Camera_obscura|l1 = Camera obscura}}
The ''[[camera obscura]]'' (Latin for "dark chamber") in its simplest form is a naturally occurring phenomenon.<ref name="rideal">{{cite web |url=http://www.npg.org.uk/learning/digital/portraiture/transition-connections.php |title=The Developing Portrait: Painting Towards Photography |last=Rideal |first=Liz |author-link=Liz Rideal |work=npg.org.uk |access-date=2014-09-26 |archive-url=https://web.archive.org/web/20141019120729/http://www.npg.org.uk/learning/digital/portraiture/transition-connections.php |archive-date=2014-10-19 |url-status=live }}</ref>

A broad-leaved tree in bright sunshine will provide conditions that fulfill the requirements of a [[pinhole camera]] or a [[camera obscura]]: a bright light source (the sun), the shade that the leafy canopy provides, a flat surface onto which the image is projected and holes formed by the gaps between the leaves. The sun's image will show as a round disc, and, in a partial eclipse, as a crescent.<ref>[https://petapixel.com/2012/05/21/crescent-shaped-projections-through-tree-leaves-during-the-solar-eclipse/ Michael Zhang: "Tree leaves as 'Pinhole cameras' during a solar eclipse"]</ref>

A clear description of a camera obscura is given by Leonardo da Vinci in Codex Atlanticus (1502): (he called it ''oculus artificialis'' which means "the artificial eye")<ref>{{cite book|author1=Lynn Picknett|author2=Clive Prince|title=The Turin Shroud: How Da Vinci Fooled History|url=https://books.google.com/books?id=lzodpIzjf0QC&pg=PA182|year=2007|publisher=Simon and Schuster|isbn=978-0-7432-9217-7|page=182}}</ref>[[File:Camera obscura2.jpg|right|thumb|Camera obscura, from a manuscript of military designs. 17th century, possibly Italian]]<blockquote>If the facade of a building, or a place, or a landscape is illuminated by the sun and a small hole is drilled in the wall of a room in a building facing this, which is not directly lighted by the sun, then all objects illuminated by the sun will send their images through this aperture and will appear, upside down, on the wall facing the hole.</blockquote>

In another notebook, he wrote:[[File:Camerae-obscurae.jpg|thumb|1840–1841 [[Camera obscura|camerae obscurae]] and plates for daguerreotype called "Grand Photographe" produced by [[Charles Chevalier]] ([[Musée des Arts et Métiers]])]]<blockquote>You will catch these pictures on a piece of white paper, which placed vertically in the room not far from that opening, and you will see all the above-mentioned objects on this paper in their natural shapes or colors, but they will appear smaller and upside down, on account of crossing of the rays at that aperture. If these pictures originate from a place which is illuminated by the sun, they will appear colored on the paper exactly as they are. The paper should be very thin and must be viewed from the back.<ref>[http://www.kirriemuircameraobscura.com/history-camera-obscuras Kirriemuir Camera Obscura ''History of Camera Obscuras'']</ref></blockquote>

In the 16th century, [[Daniele Barbaro]] suggested replacing the small hole with a larger hole and an old man's spectacle lens (a [[Lens (optics)#Types of simple lenses|biconvex lens]] for correcting long-sightedness), which produced a much brighter and sharper image.<ref name="rideal" /><ref>{{cite web |url=http://brightbytes.com/cosite/what.html |title=What is a camera obscura? |last1=Wilgus |first1=Jack |last2=Wilgus |first2=Beverly |date=August 2004 |publisher=brightbytes.com |access-date=2013-07-16 |archive-url=https://web.archive.org/web/20170307162314/http://brightbytes.com//cosite/what.html |archive-date=2017-03-07 |url-status=live }}</ref><ref>{{cite web |url=https://www.bbc.co.uk/history/british/empire_seapower/vermeer_camera_01.shtml |title=Vermeer and the Camera Obscura |last=Steadman |first=Philip |date=17 February 2012 |publisher=BBC |access-date=15 July 2013 |archive-url=https://web.archive.org/web/20101129052642/http://www.bbc.co.uk/history/british/empire_seapower/vermeer_camera_01.shtml |archive-date=29 November 2010 |url-status=live |df=dmy-all}}</ref><ref>[https://www.youtube.com/watch?v=gvzpu0Q9RTU Making a camera obscura in your room. ''National Geographic'']</ref>

By the late 18th century, small, easily portable box-form units equipped with a simple lens, an internal mirror, and a [[ground glass]] screen had become popular among affluent amateurs for making sketches of landscapes and architecture. The camera was pointed at the scene and steadied, a sheet of thin paper was placed on top of the ground glass, then a pencil or pen could be used to trace over the image projected from within. The beautiful but fugitive little light-paintings on the screen inspired several people to seek some way of capturing them more completely and effectively—and automatically—by means of chemistry.

Daguerre, a skilled professional artist, was familiar with the ''camera obscura'' as an aid for establishing correct proportion and [[perspective (visual)|perspective]], sometimes very useful when planning out the celebrated theatrical scene backdrops he painted and the even larger ultra-realistic panoramas he exhibited in his popular [[Diorama]].