Editing Daguerreotype (section)

== Portraiture ==
In one early attempt at portraiture, a Swedish amateur daguerreotypist caused his sitter nearly to lose an eye because of practically staring into the sun during the five-minute exposure.<ref>{{harv|Eder|1978|p=187}}. The amateur daguerreotypist was Lieutenant Lars Jesper Benzelstierna and his sitter was the actor Georg Dahlqvist.</ref>

Even with fast lenses and much more sensitive plates, under portrait studio lighting conditions an exposure of several seconds was necessary on the brightest of days, and on hazy or cloudy days the sitter had to remain still for considerably longer. The head rest was already in use for portrait painting.

Establishments producing daguerreotype portraits generally had a daylight studio built on the roof, much like a greenhouse. Whereas later in the history of photography artificial electric lighting was done in a dark room, building up the light with hard spotlights and softer floodlights, the daylight studio was equipped with screens and blinds to control the light, to reduce it and make it unidirectional, or diffuse it to soften harsh direct lighting. Blue filtration was sometimes used to make it easier for the sitter to tolerate the strong light, as a daguerreotype plate was almost exclusively sensitive to light at the blue end of the spectrum and filtering out everything else did not significantly increase the exposure time.

Usually, it was arranged so that sitters leaned their elbows on a support such as a posing table, the height of which could be adjusted, or else head rests were used that did not show in the picture, and this led to most daguerreotype portraits having stiff, lifeless poses. Some exceptions exist, with lively expressions full of character, as photographers saw the potential of the new medium, and would have used the [[tableau vivant]] technique. These are represented in museum collections and are the most sought after by private collectors today.<ref>{{cite web |url=http://www.musee-orsay.fr/en/events/exhibitions/archives/archives.html?zoom=1&tx_damzoom_pi1%5BshowUid%5D=108982&cHash=b461a5bf10 |title=''A Game of Chess'' (Circa 1850) |publisher=musee-orsay.fr |access-date=2012-11-05 |archive-url=https://web.archive.org/web/20131116073153/http://www.musee-orsay.fr/en/events/exhibitions/archives/archives.html?zoom=1&tx_damzoom_pi1%5BshowUid%5D=108982&cHash=b461a5bf10 |archive-date=2013-11-16 |url-status=live }}</ref> In the case of young children, their [[Hidden mother photography|mothers were sometimes hidden]] in the frame, to calm them and keep them still so as to prevent blurring.<ref name="Bathurst 2013">{{cite news |last1=Bathurst |first1=Bella |title=The lady vanishes: Victorian photography's hidden mothers |url=https://www.theguardian.com/artanddesign/2013/dec/02/hidden-mothers-victorian-photography |access-date=28 January 2018 |work=The Guardian |date=2 December 2013 |archive-url=https://web.archive.org/web/20180118104008/https://www.theguardian.com/artanddesign/2013/dec/02/hidden-mothers-victorian-photography |archive-date=18 January 2018 |url-status=live |df=dmy-all}}</ref>

[[File:Device to hold heads during Daguerreotype exposure.JPG|thumb|upright|Device to hold heads still during the long exposure time required to make a daguerreotype portrait]]<!-- material beneath does not belong in this subsection -->
The image in a daguerreotype is often described as being formed by the [[Amalgam (chemistry)|amalgam]], or alloy, of [[Mercury (element)|mercury]] and [[silver]] because mercury vapor from a pool of heated mercury is used to develop the plate; but using the [[A. E. Becquerel|Becquerel]] process (using a red filter and extra exposure) daguerreotypes can be produced without mercury, and chemical analysis shows that there is no mercury in the final image with the Becquerel process.<ref>{{harv|Barger|White|2000|p=148}} "[The Becquerel method] does not use mercury at all. Becquerel plates are made by sensitizing a polished daguerreotype plate with iodine vapor only ... the exposed plate is ... given an overall exposure to red light until a print-out image appears ... image particles formed in this way are composed only of silver."</ref>  This brings into question the theory that the image is formed of amalgam with mercury development.

Although the daguerreotype process could only produce a single image at a time, copies could be created by re-daguerreotyping the original.<ref>{{harv|Barger|White|2000|p=42}}</ref> As with any original photograph that is copied, the contrast increases. With a daguerreotype, any writing will appear back to front. Recopying a daguerreotype will make the writing appear normal and rings worn on the fingers will appear on the correct hand. Another device to make a daguerreotype the right way round would be to use a mirror when taking the photograph.

The daguerreotypes of the 1852 Omaha Indian (Native American) delegation in the Smithsonian include a daguerreotype copied in the camera, recognizable by the contrast being high and a black line down the side of the plate.<ref>{{cite web |url=http://www.indiana.edu/~aisri/Preponderance/nmnh_Preponderance_6_Article2.html |title=A Preponderance of Evidence: The 1852 Omaha Indian Delegation Daguerreotypes Recovered |publisher=Indiana University Bloomington |access-date=2013-06-25 |archive-url=https://web.archive.org/web/20140108103014/http://www.indiana.edu/~aisri/Preponderance/nmnh_Preponderance_6_Article2.html |archive-date=2014-01-08 |url-status=dead }}</ref>