Editing Camera (section)

=== Exposure control ===
{{Main|Exposure (photography)}}

==== Aperture ====
{{Main|Aperture}}
[[File: Lenses with different apertures.jpg|thumb|Different apertures of a lens]]

Light enters the camera through an aperture, an opening adjusted by overlapping plates called the aperture ring.<ref name="Columbia">{{Cite encyclopedia|title=camera|encyclopedia=The Columbia Encyclopedia|publisher=Columbia University Press|url=https://www.pin1.harvard.edu/pin/authenticate?__authen_application=HUL_ACC_MGMT_SVC&__hulaccess_gateway=ezproxy&__hulaccess_resource=zorecord&__hulaccess_url=https%3A%2F%2Fsearch.credoreference.com%2Fcontent%2Ftopic%2Fcamera|last=Columbia University|date=2018|editor=Paul Lagasse|edition=8|url-access=subscription}}</ref><ref name="How-Stuff-Works">{{Cite web|title=How Cameras Work|url=https://electronics.howstuffworks.com/camera.htm/printable|access-date=13 December 2019|work=How Stuff Works|date=21 March 2001|archive-date=14 December 2019|archive-url=https://web.archive.org/web/20191214060333/https://electronics.howstuffworks.com/camera.htm/printable|url-status=live}}</ref><ref name="Dawn">Laney, Dawn A. ..BA, MS, CGC, CCRC. “Camera Technologies.” ''Salem Press Encyclopedia of Science'', June 2020. Accessed 6 February 2022.</ref> Typically located in the lens,<ref name="Warren-Camera">{{Cite encyclopedia|title=Camera: An Overview|encyclopedia=Encyclopedia of twentieth-century photography|publisher=Routledge|location=New York|date=2006|editor=Lynne Warren|isbn=978-1-57958-393-4}}</ref> this opening can be widened or narrowed to alter the amount of light that strikes the film or sensor.<ref name="Columbia" />  The size of the aperture can be set manually, by rotating the lens or adjusting a dial or automatically based on readings from an internal light meter.<ref name="Columbia" />

As the aperture is adjusted, the opening expands and contracts in increments called [[f-number|''f-stops'']].{{efn|These f-stops are also referred to as ''f-numbers'', ''stop numbers'', ''steps'' or ''stops''. The f-number is the focal length of the lens divided by the diameter of the effective aperture.}}<ref name="Columbia" /> The smaller the f-stop, the more light is allowed to enter the lens, increasing the exposure. Typically, f-stops range from {{f/}}1.4 to {{f/}}32{{Efn|Theoretically, they can extend to {{f/}}64 or higher.<ref name="Dawn" />}} in standard increments: 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, and 32.<ref name="Britannica-Technology">{{Cite encyclopedia|title=technology of photography|encyclopedia=Britannica Academic|url=https://academic-eb-com.ezp-prod1.hul.harvard.edu/levels/collegiate/article/technology-of-photography/108552#36407.toc|access-date=13 December 2019|url-access=subscription|archive-date=10 November 2023|archive-url=https://web.archive.org/web/20231110043035/https://www.pin1.harvard.edu/cas/login?service=https%3A%2F%2Fkey-idp.iam.harvard.edu%2Fidp%2FAuthn%2FExternal%3Fconversation%3De1s1%26entityId%3Dezp-prod1.hul.harvard.edu%2Flts%2Fezproxyprod%2Fsp#36407.toc|url-status=live}}</ref> The light entering the camera is halved with each increasing increment.<ref name="Warren-Camera" />[[File:Daisies-Focus.jpg|thumb|right|The distance range in which objects appear clear and sharp, called ''[[depth of field]]'', can be adjusted by many cameras. This allows a photographer to control which objects appear in focus, and which do not.|alt=An image of flowers, with one in focus. The background is out of focus.]]

The wider opening at lower f-stops narrows the range of focus so the background is blurry while the foreground is in focus. This [[depth of field]] increases as the aperture closes. A narrow aperture results in a high depth of field, meaning that objects at many different distances from the camera will appear to be in focus.<ref name="Warren-35mm">{{Cite encyclopedia|title=Camera: 35&nbsp;mm|encyclopedia=Encyclopedia of twentieth-century photography|publisher=Routledge|location=New York|date=2006|editor=Lynne Warren|isbn=978-1-57958-393-4}}</ref> What is acceptably in focus is determined by the [[circle of confusion]], the photographic technique, the equipment in use and the degree of magnification expected of the final image.<ref>{{cite book|title=The British Journal Photographic Almanac|date=1956|publisher=Henry Greenwood and Co. Ltd|pages= 468–471}}</ref>

==== Shutter ====
{{Main|Shutter (photography)}}

The shutter, along with the aperture, is one of two ways to control the amount of light entering the camera. The [[Shutter (photography)|shutter]] determines the duration that the light-sensitive surface is exposed to light. The shutter opens, light enters the camera and exposes the film or sensor to light, and then the shutter closes.<ref name="Warren-Camera" /><ref name="Focal">{{Cite encyclopedia|publisher=Elsevier|isbn=978-0-240-80740-9|pages=770–771|last=Rose|first=B|title=The Camera Defined|encyclopedia=The Focal Encyclopedia of Photography|access-date=12 December 2019|date=2007|doi=10.1016/B978-0-240-80740-9.50152-5|url=https://linkinghub.elsevier.com/retrieve/pii/B9780240807409501525|archive-date=14 December 2019|archive-url=https://web.archive.org/web/20191214060334/https://linkinghub.elsevier.com/retrieve/pii/B9780240807409501525|url-status=live|url-access=subscription}}</ref>

There are two types of mechanical shutters: the leaf-type shutter and the focal-plane shutter. The leaf-type uses a circular iris diaphragm maintained under spring tension inside or just behind the lens that rapidly opens and closes when the shutter is released.<ref name="Britannica-Technology" /> [[File: Focal-plane shutter.jpg|thumb|A focal-plane shutter. In this shutter, the metal shutter blades travel vertically.]]
More commonly, a [[focal-plane shutter]] is used.<ref name="Warren-Camera" /> This shutter operates close to the film plane and employs metal plates or cloth curtains with an opening that passes across the light-sensitive surface. The curtains or plates have an opening that is pulled across the film plane during exposure. The focal-plane shutter is typically used in single-lens reflex (SLR) cameras, since covering the film (rather than blocking the light passing through the lens) allows the photographer to view the image through the lens at all times, except during the exposure itself. Covering the film also facilitates removing the lens from a loaded camera, as many SLRs have interchangeable lenses.<ref name="Columbia" /><ref name="Britannica-Technology" />

A [[digital camera]] may use a mechanical or electronic shutter, the latter of which is common in smartphone cameras. Electronic shutters either record data from the entire sensor simultaneously (a global shutter) or record the data line by line across the sensor (a rolling shutter).<ref name="Columbia" /> In movie cameras, a rotary shutter opens and closes in sync with the advancement of each frame of film.<ref name="Columbia" /><ref>{{Cite encyclopedia|title=Motion-picture camera|encyclopedia=Encyclopedia Britannica|access-date=12 December 2019|url=https://www-britannica-com.ezp-prod1.hul.harvard.edu/technology/motion-picture-camera}}{{dead link|date=November 2023}}</ref>

The duration for which the shutter is open is called the ''[[shutter speed]]'' or ''exposure time''. Typical exposure times can range from one second to 1/1,000 of a second, though longer and shorter durations are not uncommon. In the early stages of photography, exposures were often several minutes long. These long exposure times often resulted in blurry images, as a single object is recorded in multiple places across a single image for the duration of the exposure. To prevent this, shorter exposure times can be used. Very short exposure times can capture fast-moving action and eliminate motion blur.<ref name="Philip's">{{Cite encyclopedia|publisher=Philip's|isbn=978-0-19-954609-1|title=Camera|encyclopedia=World Encyclopedia|access-date=12 December 2019|url=https://archive.org/details/worldencyclopedi00oxfo|url-access=registration|year=2004}}</ref><ref name="Britannica-Technology" /><ref name="Columbia" /><ref name="Warren-Camera" /> However, shorter exposure times require more light to produce a properly exposed image, so shortening the exposure time is not always possible.

Like aperture settings, exposure times increment in powers of two. The two settings determine the exposure value (EV), a measure of how much light is recorded during the exposure. There is a direct relationship between the exposure times and aperture settings so that if the exposure time is lengthened one step, but the aperture opening is also narrowed one step, then the amount of light that contacts the film or sensor is the same.<ref name="Warren-Camera" />

==== Light meter ====
{{Main|Light meter}}

[[File: Sekonic L-358 Flash Master.jpg|thumb|A handheld digital light meter showing an exposure of 1/200th at an aperture of f/11, at ISO 100. The light sensor is on top, under the white diffusing hemisphere.]]
In most modern cameras, the amount of light entering the camera is measured using a built-in light meter or exposure meter.{{Efn|Some photographers use handheld [[exposure meter]]s independent of the camera and use the readings to manually set the exposure settings on the camera.<ref name="Britannica-Camera" />|name=|}} Taken through the lens (called ''{{Abbr|TTL|through the lens}} metering''), these readings are taken using a panel of light-sensitive [[semiconductor]]s.<ref name="How-Stuff-Works" /> They are used to calculate optimal exposure settings. These settings are typically determined automatically as the reading is used by the camera's [[microprocessor]]. The reading from the light meter is incorporated with aperture settings, exposure times, and film or sensor sensitivity to calculate the optimal exposure.{{Efn|Film canisters typically contain a DX code that can be read by modern cameras so that the camera's computer knows the sensitivity of the film, the ISO.<ref name="Warren-Camera" />]|name=|}}

[[Light meter]]s typically average the light in a scene to 18% middle gray. More advanced cameras are more nuanced in their metering—weighing the center of the frame more heavily (center-weighted metering), considering the differences in light across the image (matrix metering), or allowing the photographer to take a light reading at a specific point within the image (spot metering).<ref name="Warren-35mm" /><ref name="Philip's" /><ref name="Britannica-Camera">{{Cite encyclopedia|title=camera|encyclopedia=Britannica Academic|url=https://academic-eb-com.ezp-prod1.hul.harvard.edu/levels/collegiate/article/camera/18803|access-date=12 December 2019|url-access=subscription|archive-date=10 November 2023|archive-url=https://web.archive.org/web/20231110042914/https://www.pin1.harvard.edu/cas/login?service=https%3A%2F%2Fkey-idp.iam.harvard.edu%2Fidp%2FAuthn%2FExternal%3Fconversation%3De1s1%26entityId%3Dezp-prod1.hul.harvard.edu%2Flts%2Fezproxyprod%2Fsp|url-status=live}}</ref><ref name="Columbia" />