Editing Aperture (section)

===Maximum and minimum apertures===
{{further|Lens speed}}
The specifications for a given lens typically include the maximum and minimum aperture (opening) sizes, for example, {{f/|0.95}} – {{f/|22}}. In this case, {{f/|0.95}} is currently the maximum aperture (the widest opening on a full-frame format for practical use<ref name="wayne">{{Cite web|last=wayne|date=2021-05-03|title=Argus -Laowa f/0.95 Large Aperture Lenses - Ultra-fast lens|url=https://www.venuslens.net/argus-large-aperture-lenses-laowa/|access-date=2021-09-06}}</ref>), and {{f/|22}} is the minimum aperture (the smallest opening). The maximum aperture tends to be of most interest and is always included when describing a lens. This value is also known as the [[lens speed|lens "speed"]], as it affects the exposure time. As the aperture area is proportional to the light admitted by a lens or an optical system, the aperture diameter is proportional to the square root of the light admitted, and thus inversely proportional to the square root of required exposure time, such that an aperture of {{f/|2}} allows for exposure times one quarter that of {{f/|4}}. ({{f/|2}} is 4 times larger than {{f/|4}} in the aperture area.)

[[File:16 minolta 50mm.jpg|thumb|right|The aperture range of a 50 mm Minolta lens, {{f/|1.4}} – {{f/|16}}]]

Lenses with apertures opening {{f/|2.8}} or wider are referred to as "fast" lenses, although the specific point has changed over time (for example, in the early 20th century aperture openings wider than {{f/|6}} were considered fast.<ref>{{Cite web|url=https://lenscross.com/2021/08/basics-of-photography-a-beginners-guide/|title = Basics of Photography: A Beginner's Guide|date = 31 August 2021}}</ref> The fastest lenses for the common [[135 film|35 mm film]] format in general production have apertures of {{f/|1.2}} or {{f/|1.4}}, with more at {{f/|1.8}} and {{f/|2.0}}, and many at {{f/|2.8}} or slower; {{f/|1.0}} is unusual, though sees some use. When comparing "fast" lenses, the [[Film format|image format]] used must be considered. Lenses designed for a small format such as [[Half-frame camera|half frame]] or [[APS-C]] need to project a much smaller [[image circle]] than a lens used for [[Large format (photography)|large format]] photography. Thus the optical elements built into the lens can be far smaller and cheaper.

In exceptional circumstances lenses can have even wider apertures with f-numbers smaller than 1.0; see [[Lens speed#Fast lenses|lens speed: fast lenses]] for a detailed list. For instance, both the current Leica Noctilux-M 50mm ASPH and a 1960s-era Canon 50mm rangefinder lens have a maximum aperture of {{f/|0.95}}.<ref>{{cite web|url=https://gizmodo.com/5048115/leicas-11000-noctilux-50mm-f095-lens-is-a-nightvision-owl-eye-for-your-camera|title=Leica's $11,000 Noctilux 50mm f/0.95 Lens Is a Nightvision Owl Eye For Your Camera|first=John|last=Mahoney|website=gizmodo.com|date=10 September 2008 |access-date=15 April 2018}}</ref> Cheaper alternatives began appearing in the early 2010s, such as the [[Cosina Voigtländer]] {{f/|0.95}} Nokton (several in the {{val|10.5|-|60|u=mm}} range) and {{f/|0.8}} ({{val|29|u=mm}}) Super Nokton manual focus lenses in the for the [[Micro Four-Thirds System]],<ref>{{cite web |title= Micro Four Thirds Mount Lenses |website= Cosina Voigtlander |date= 19 September 2021 |url= https://www.cosina.co.jp/voigtlander/en/micro-four-thirds/ |access-date= 2023-09-15 |archive-url= https://web.archive.org/web/20220521061918/https://www.cosina.co.jp/voigtlander/en/micro-four-thirds/ |archive-date= 2022-05-21 |url-status= live}}</ref> and the [[Venus Optics]] (Laowa) Argus {{val|35|u=mm}} {{f/|0.95}}.<ref name="wayne"/>

Professional lenses for some movie cameras have f-numbers as small as {{f/|0.75}}. [[Stanley Kubrick]]'s film ''[[Barry Lyndon]]'' has scenes shot by candlelight with a [[Carl Zeiss Planar 50mm f/0.7|NASA/Zeiss 50mm f/0.7]],<ref>{{cite magazine |last1= Lightman |first1= Herb A. |last2= DiGiulio |first2= Ed |date= 16 March 2018 |orig-date= March 1976 |magazine= [[American Cinematographer]] |title= Photographing Kubrick's 'Barry Lyndon' |url= https://theasc.com/articles/flashback-barry-lyndon |access-date= 2023-09-15 |archive-url= https://web.archive.org/web/20230207011224/https://theasc.com/articles/flashback-barry-lyndon |archive-date= 2023-02-07 |url-status= live}}</ref> the fastest lens in film history. Beyond the expense, these lenses have limited application due to the correspondingly shallower [[Depth of field|depth of field (DOF)]]&nbsp;– the scene must either be shallow, shot from a distance, or will be significantly defocused, though this may be the desired effect.

Zoom lenses typically have a maximum relative aperture (minimum f-number) of {{f/|2.8}} to {{f/|6.3}} through their range. High-end lenses will have a constant aperture, such as {{f/|2.8}} or {{f/|4}}, which means that the relative aperture will stay the same throughout the zoom range. A more typical consumer zoom will have a variable maximum relative aperture since it is harder and more expensive to keep the maximum relative aperture proportional to the focal length at long focal lengths; {{f/|3.5}} to {{f/|5.6}} is an example of a common variable aperture range in a consumer zoom lens.

By contrast, the minimum aperture does not depend on the focal length&nbsp;– it is limited by how narrowly the aperture closes, not the lens design&nbsp;– and is instead generally chosen based on practicality: very small apertures have lower sharpness due to diffraction at aperture edges, while the added depth of field is not generally useful, and thus there is generally little benefit in using such apertures. Accordingly, DSLR lens typically have minimum aperture of {{f/|16}}, {{f/|22}}, or {{f/|32}}, while [[large format]] may go down to {{f/|64}}, as reflected in the name of [[Group f/64]]. Depth of field is a significant concern in [[macro photography]], however, and there one sees smaller apertures. For example, the [[Canon MP-E 65mm f/2.8 1-5x Macro lens|Canon MP-E 65mm]] can have effective aperture (due to magnification) as small as {{f/|96}}. The [[Pinhole camera|pinhole]] optic for [[Lensbaby]] creative lenses has an aperture of just {{f/|177}}.<ref>{{cite web|url=http://www.lensbaby.com/optics-pinhole.php |title=Pinhole and Zone Plate Photography for SLR Cameras |work=Lensbaby Pinhole optic |url-status=dead |archive-url=https://web.archive.org/web/20110501093047/http://www.lensbaby.com/optics-pinhole.php |archive-date=1 May 2011 }}</ref>

<gallery>
Image:Jonquil flowers at f32.jpg|{{f/|32}} – small aperture and slow shutter
Image:Jonquil flowers at f5.jpg|{{f/|5.6}} – large aperture and fast shutter
Image:Aperture Example Wall.jpg|{{f/|22}} – small aperture and slower shutter (Exposure time: 1/80)
Image:Aperture Example Wall 2.jpg|{{f/|3.5}} – large aperture and faster shutter (Exposure time: 1/2500)
Image:Povray focal blur animation.gif|Changing a camera's aperture value in half-stops, beginning with {{f/|256}} and ending with {{f/|1}}
Image:Povray focal blur animation mode tan.gif|Changing a camera's aperture diameter from zero to infinity
</gallery>