Lens speed refers to the maximum

aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. An ...

diameter, or minimum

f-number In optics, the f-number of an optical system such as a camera lens is the ratio of the system's focal length to the diameter of the entrance pupil ("clear aperture").Smith, Warren ''Modern Optical Engineering'', 4th Ed., 2007 McGraw-Hill ...

, of a

photographic lens A camera lens (also known as photographic lens or photographic objective) is an optical lens or assembly of lenses used in conjunction with a camera body and mechanism to make images of objects either on photographic film or on other media capa ...

. A lens with a larger than average maximum aperture (that is, a smaller minimum f-number) is called a "fast lens" because it can achieve the same exposure as an average lens with a faster

shutter speed In photography, shutter speed or exposure time is the length of time that the film or digital sensor inside the camera is exposed to light (that is, when the camera's shutter (photography), shutter is open) when taking a photograph. The am ...

. Conversely, a smaller maximum aperture (larger minimum f-number) is "slow" because it delivers less light intensity and requires a slower (longer) shutter speed. A fast lens speed is desirable in taking pictures in dim light, for stability with long

telephoto A telephoto lens, in photography and cinematography, is a specific type of a long-focus lens in which the physical length of the lens is shorter than the focal length. This is achieved by incorporating a special lens group known as a ''telephoto ...

lenses, and for controlling

depth of field The depth of field (DOF) is the distance between the nearest and the furthest objects that are in acceptably sharp focus in an image captured with a camera. Factors affecting depth of field For cameras that can only focus on one object di ...

and bokeh, especially in portrait photography, as well as for

sports photography Sports photography refers to the genre of photography that covers all types of sports. In the majority of cases, professional sports photography is a branch of ''photojournalism,'' while amateur sports photography, such as photos of childre ...

and

photojournalism Photojournalism is journalism that uses images to tell a news story. It usually only refers to still images, but can also refer to video used in broadcast journalism. Photojournalism is distinguished from other close branches of photography (suc ...

. Lenses may also be referred to as being "faster" or "slower" than one another; so an lens can be described as faster than an 5.6 despite 3.5 not generally being considered "fast" outright. What ''is'' considered fast largely depends on focal length, image diameter (i.e. format covered, such as APS, full frame, medium format), and in the case of zoom lenses, zoom factor.

Tradeoffs

Attaining maximum lens speed requires engineering tradeoffs, and as such, "

prime A prime number (or a prime) is a natural number greater than 1 that is not a product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime because the only way ...

" (fixed focal length) lenses are generally faster than zoom lenses. With 35mm film cameras and full-frame digital cameras, the fastest lenses are typically in the " normal lens" range near 50mm; here, there are several relatively inexpensive high-quality fast lenses available. For example, the Canon EF 50mm 1.8 II or Nikon AF Nikkor 50mm 1.8D are very inexpensive, but quite fast and optically well-regarded. Old fast manual focus lenses, such as the Nikkor-S(C) or Nikkor AI-S 50mm 1.4, or Canon's FD and M39 counterparts, were historically produced abundantly, and are thus sold relatively inexpensively on the used lens market. Especially outside of the "normal" focal length, lens speed also tends to correlate with the price and/or quality of the lens. This is because lenses with larger maximum apertures require greater care with regard to design, precision of manufacture, special coatings and quality of glass. At wide apertures,

spherical aberration In optics, spherical aberration (SA) is a type of aberration found in optical systems that have elements with spherical surfaces. Lenses and curved mirrors are prime examples, because this shape is easier to manufacture. Light rays that strike a ...

becomes more significant and must be corrected. Thus, faster

and wide-angle retrofocus designs tend to be much more expensive. A telecompressor, also known as a speed booster, may be used to increase the speed of a lens with a corresponding reduction to its focal length. For example, the Metabones 0.58x BMPCC speed booster may be combined with a 1.2 lens to produce 0.74.

Fast lenses

While the fastest lenses in general production in the 2010s were 1.2 or 1.4, the 2020s have seen several 0.95 lenses, see below. What is considered "fast" has evolved to lower f-numbers over the years, due to advances in

lens design Optical lens design is the process of designing a lens to meet a set of performance requirements and constraints, including cost and manufacturing limitations. Parameters include surface profile types (spherical, aspheric, holographic, diffractive, ...

optical manufacturing Optical manufacturing and testing spans an enormous range of manufacturing procedures and optical test configurations. The manufacture of a conventional spherical lens typically begins with the generation of the optic's rough shape by grinding a ...

, quality of glass, optical coatings, and the move toward smaller imaging formats. For example, the

1911 Encyclopædia Britannica A notable ongoing event was the race for the South Pole. Events January * January 1 – A decade after federation, the Northern Territory and the Australian Capital Territory are added to the Commonwealth of Australia. * Ja ...

states that "... ensesare also sometimes classified according to their rapidity, as expressed by their effective apertures, into extra rapid, with apertures larger than 6; rapid, with apertures from 6 to 8; slow, with apertures less than 11" whilst today, 6 would be deemed at the rather slow end. For scale, note that 0.5, 0.7, 1.0, 1.4, and 2.0 are each 1 f-stop apart (2× as fast), as an f-stop corresponds to a factor of the

square root of 2 The square root of 2 (approximately 1.4142) is a positive real number that, when multiplied by itself, equals the number 2. It may be written in mathematics as \sqrt or 2^, and is an algebraic number. Technically, it should be called the princi ...

, about 1.4. Thus around 1.0, a change of 0.1 corresponds to about 1/4 of an f-stop (by

linear approximation In mathematics, a linear approximation is an approximation of a general function using a linear function (more precisely, an affine function). They are widely used in the method of finite differences to produce first order methods for solving o ...

): 1.0 is about 50% faster than 1.2, which is about 50% faster than 1.4. , Canon, Nikon, Pentax and Sony all make an autofocus 50mm 1.4 lens. These are not unusual lenses and are relatively inexpensive. As of 2022, Canon also makes autofocus 50mm and 85mm 1.2 lenses, while Nikon makes a manual focus 58mm 0.95 lens and an autofocus 85mm 1.4; see

Canon EF 50mm lens The EF 50mm lenses are a group of normal prime lenses made by Canon that share the same focal length. These lenses are based on the classic double-Gauss lens, with the f/1.8 being a standard six-element double-Gauss with an air gap and powers betw ...

es and

Canon EF 85mm lens The EF 85mm lenses are a group of medium telephoto prime lenses made by Canon Inc. that share the same focal length. These lenses have an EF type mount that fits the Canon EOS line of cameras. This 85mm focal length is "perfect for portraiture" ...

es for details. Pentax makes a 50mm 1.4 lens and 55mm 1.4 lens for

APS-C Advanced Photo System type-C (APS-C) is an image sensor format approximately equivalent in size to the Advanced Photo System film negative in its C ("Classic") format, of 25.1×16.7 mm, an aspect ratio of 3:2 and Ø 31.15 mm field ...

cameras; see

Pentax lenses Pentax lenses were first badged as Takumar. The Takumar branded lenses were well respected for their line of Super Takumar, which designated the high performance coating applied to the lens as well as the optical formulas used to make them. The ...

. Sony makes several 50mm 1.4 lenses as well as a 50mm 1.2. The maximum exposure time for hand-held photography can be increased with an

image stabilisation Image stabilization (IS) is a family of techniques that reduce blurring associated with the motion of a camera or other imaging device during exposure. Generally, it compensates for pan and tilt (angular movement, equivalent to yaw and pit ...

system. In 2014,

Panasonic formerly between 1935 and 2008 and the first incarnation of between 2008 and 2022, is a major Japanese multinational conglomerate corporation, headquartered in Kadoma, Osaka. It was founded by Kōnosuke Matsushita in 1918 as a lightbulb ...

introduced the fastest lens with in-built stabilisation, the

Leica Leica Camera AG () is a German company that manufactures cameras, optical lenses, photographic lenses, binoculars, rifle scopes and microscopes. The company was founded by Ernst Leitz in 1869 (Ernst Leitz Wetzlar), in Wetzlar, Germany. ...

Nocticron Nocticron („Night-time“ from latin ''nox, noctis'' „night“ and ancient Greek ''kronos'' „time“) is the brand name of Leica lenses with an extreme speed of f/1.2. Because of the large aperture size and its image stabilisation system ...

42.5 mm f/1.2, which can even be operated with dual image stabilisation (Dual I.S.), provided that the camera body has an additional stabilising system at the image sensor. In the mid 1960s, there was something of a fad for fast lenses among the major manufacturers. In 1966, in response to the trend,

Carl Zeiss Carl Zeiss (; 11 September 1816 – 3 December 1888) was a German scientific instrument maker, optician and businessman. In 1846 he founded his workshop, which is still in business as Carl Zeiss AG. Zeiss gathered a group of gifted practica ...

displayed a prop lens christened the Super-Q-Gigantar 40mm 0.33 at

photokina Photokina (rendered in the promoters' branding as "photokina") is a trade fair held in Europe for the photographic and imaging industries. It is the world's largest such trade fair. The first Photokina was held in Cologne, Germany, in 1950, a ...

. Made from various parts found around the factory (the lenses came from a darkroom condenser enlarger), the claimed speed and focal lengths were purely nominal and it wasn't usable for photography.

Maximum possible speed

Theoretically, the smallest f-number is 0 (or numerical aperture of 1), corresponding to a lens with an infinite

entrance pupil In an optical system, the entrance pupil is the optical image of the physical aperture stop, as 'seen' through the front (the object side) of the lens system. The corresponding image of the aperture as seen through the back of the lens system i ...

diameter. In practice, that cannot be reached due to mechanical constraints of the camera system (shutter clearance, mount diameter). Even for systems that can be designed without significant constraints on lens size and image plane distance (e.g. microscopy and

photolithography In integrated circuit manufacturing, photolithography or optical lithography is a general term used for techniques that use light to produce minutely patterned thin films of suitable materials over a substrate, such as a silicon wafer (electroni ...

systems), the cost of going beyond a numerical aperture of 0.95 (f/0.164) is usually prohibitive. In SLR camera systems, typical mount diameters are in the range of 44–54 mm, with flange distances around 45 mm. This limits the maximum possible f-number to 1.0 to 1.2, with rather strong vignetting towards the edges of the image. Flange distances are significantly smaller for

rangefinder A rangefinder (also rangefinding telemeter, depending on the context) is a device used to measure distances to remote objects. Originally optical devices used in surveying, they soon found applications in other fields, such as photography an ...

and

mirrorless A mirrorless camera is a photo camera featuring a single, removable lens and a digital display. The camera does not have a reflex mirror or optical viewfinder like a digital single-lens reflex (DSLR) camera, but may have an electronic vi ...

cameras (even below 20 mm), theoretically enabling designs down to something like f/0.7 or even faster. The chance of seeing these in practice will be slim, since their cost and weight are likely not competitive with respect to equivalent imaging solutions employing larger sensors.

List of ultrafast lenses

Some of the fastest camera lenses in production were as follows: * Cosina Voigtländer Nokton 10.5mm, 17.5mm, 25mm, 42.5mm, 60mm 0.95 for Micro Four Thirds mount *Vantage One T1.0 Cine lenses from 17.5mm to 120mm (Super35mm Spherical Primes) *SLR Magic 25mm T/0.95 * Cosina Voigtländer Super Nokton 29mm 0.8 Micro Four Thirds mount * SLR Magic 35mm T/0.95 * Handevision Ibelux 40mm 0.85 (made for Micro Four Thirds and various APS camera mounts, including Sony E-Mount and Fujifilm X-Mount) * Fujinon 43mm 0.85 *

Noctilux-M 50mm 0.95 ASPH (announced on September 15, 2008, then the fastest aspherical lens to have reached mass production; MSRP of £6290 or approximately US$10,000). * Zhongyi Mitakon 50mm and 35mm 0.95 in various optical versions and mounts, of which at least the 50mm for Leica M rangefinders has been found to in fact only be 1.06! * Nikon Noct-Nikkor Z 58mm 0.95 The following lenses are no longer in production : * American Optical 81mm 3.259" 0.38 Solid Schmidt Mirror lens (designed for aerial reconnaissance, documented in 1967, but most likely never built) * GOI CV 20mm 0.5 Mirror lens (2.9 mm image diameter, 1948; design and glass types used are well documented for anyone wanting to build thei
own
* Signal Corps Engineering 33mm 0.6 * GOI Iskra-3 72mm 0.65 Mirror lens * Fujinon-IDEAX 125mm 0.67 and/or 0.85 (X-ray lens, two speeds quoted on front ring) * Zeiss Planar 50mm 0.7 (Limited 10-copies production for the

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeedi ...

space program, later used on 35mm movie cameras by

Stanley Kubrick Stanley Kubrick (; July 26, 1928 – March 7, 1999) was an American film director, producer, screenwriter, and photographer. Widely considered one of the greatest filmmakers of all time, his films, almost all of which are adaptations of nove ...

for some candlelit scenes in ''

Barry Lyndon ''Barry Lyndon'' is a 1975 Period film, period drama film written, directed, and produced by Stanley Kubrick, based on the 1844 novel ''The Luck of Barry Lyndon'' by William Makepeace Thackeray. Starring Ryan O'Neal, Marisa Berenson, Patrick Ma ...

'') * Tokyo Kogaku Similar 50mm 0.7 (8 elements in 4 groups, limited production in 1944 for Japanese Army. In 1951, another three were produced, two of which were used on a

South Pole The South Pole, also known as the Geographic South Pole, Terrestrial South Pole or 90th Parallel South, is one of the two points where Earth's axis of rotation intersects its surface. It is the southernmost point on Earth and lies antipod ...

expedition) * Kinoptik Lynxar 60mm 0.7 (Reproduction lens, usable but not optimised for photography) * Wray 64mm 0.71 (Reproduction lens, usable but not optimised for photography) *

LOMO LOMO (russian: Ленинградское Oптико-Mеханическое Oбъединение, Leningradskoye Optiko-Mekhanicheskoye Obyedinenie, Leningrad Optical Mechanical Association) is a manufacturer of medical and motion-picture lens ...

60mm 0.75 (Reproduction lens, usable but not optimised for photography) *

Aerojet Delft Aerojet was an American rocket and missile propulsion manufacturer based primarily in Rancho Cordova, California, with divisions in Redmond, Washington, Orange, Virginia, Orange and Gainesville, Virginia, Gainesville in Virginia, and Camden, Ar ...

Rayxar 105mm 0.75 Full Frame aerial photography lens *

Rayxar 150mm 0.75 Medium Format aerial photography lens *

Rayxar 250mm 0.75 Large Format aerial photography lens * American Optical 43mm 1.715" 0.8 (design documented in 1967, but likely never built) *

JML Optical JML may refer to: * Java Modeling Language, a specification language for Java programs * Journal of Memory and Language, abbreviated JML * "Joiner, mover, leaver", a collection of business processes managing access to an organisation's systems with ...

64mm 0.85 *

Summar 75mm 0.85 Reproduction lens, not for photography. *

Leitz-IR 150mm 0.85 Reproduction lens, not for photography. *

Farrand Farrand may refer to: * William R. Farrand (1853–1930), American manufacturer of pianos and organs * Livingston Farrand (1867–1939), American physician and anthropologist * Royal T. Farrand (1867–1927), American football player and medical d ...

Super Farron 76mm 0.87 *

Super Farron 150mm 0.87 Medium Format aerial photography lens (design documented in 1967, but likely never built) * Canon 50mm 0.95 (made as a rangefinder-coupled version with proprietary external bayonet for Canon 7 rangefinders, and an uncoupled C-mount "TV" version) * Kiev Рекорд-4 (Rekord-4) 52mm 0.9 (rangefinder lens, remained a prototype despite better resolution than the Canon 50mm0.95 rangefinder lens) *

Nikon (, ; ), also known just as Nikon, is a Japanese multinational corporation headquartered in Tokyo, Japan, specializing in optics and imaging products. The companies held by Nikon form the Nikon Group. Nikon's products include cameras, camera ...

TV-Nikkor 35mm 0.9 (Fastest Nikon lens ever made; TV lens in M39 lens mount, 12.6 mm diameter image circle) * Noktor 50mm 0.95 (C-mount lens converted for mirrorless cameras; the actual C-mount lens is still being made as D.O. Industries Kowa Navitron, JML, Tarcus; Elgeet Navitar, SLRMagic Hyperprime, Senko, Yakumo; Goyo; Ernitec Super) * SLR Magic HyperPrime CINE and LM 50mm 0.92 T0.95 (rangefinder lens, Erwin Puts measured it to be T1.1

*

Astro Berlin Astro may refer to: Entertainment and media * Astro (South Korean band), a South Korean boy band * Astro (UB40) (1957–2021), member of the British reggae band UB40 * Astro (Chilean band), a Chilean indie rock band * Astro (Japanese band), a ...

52mm 0.95 (Super-35 Cine lens) * Leitz Perkin Elmer 4.5" 114mm 0.95 T1 (aerial photography lens, 40mm image diameter, 1967) *

Pacific Optical The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the conti ...

25mm 1.0 (Medium Format 150° Fish-eye lens, 55 mm image diameter; only 3 copies were ever made: for the Canadian Government for aurora borealis research in the late 60s/early 70s. One of these lenses was used in the production of the IMAX movie Solarmax, one is presumed lost; the cost per piece was estimated at 250,000 USD) *

Noctilux-M 50mm 1.0 (Leica M mount, 1976; discontinued and replaced 2008 with a new Noctilux, see above) * Canon EF 50mm 1.0 L USM (for Canon EOS autofocus SLRs, announced 1987, released 1989, discontinued 2009) *

Panavision Panavision is an American motion picture equipment company founded in 1953 specializing in cameras and lenses, based in Woodland Hills, California. Formed by Robert Gottschalk as a small partnership to create anamorphic projection lenses duri ...

50mm 1.0 (Super-35 cine lens) * Nikkor-O 50mm 1.0 Prototype lens for Nikkor-S Rangefinder camera *

ELCAN 90mm 1.0 *

Wild Heerbrugg The Wild (Heerbrugg) company (pronounced "vilt") was founded in 1921 in Switzerland. The company manufactured optical instruments, such as surveying instruments, microscopes and instruments for photogrammetry among others. The company chan ...

Reconar 98mm 1.0 Medium Format aerial photography lens * Kollmorgen 153mm 1.0 * Zeiss UR 250mm 1.0 * Canon 8.5–25.5mm 1.0 zoom lens (made 1975–1983 for the 310XL Super 8mm silent and sound camera series, the fastest zoom lens ever made for Super8, originally advertised as facilitating "shooting at candlelight" in combination with 160-ASA films.)Lossau, Jürgen (2003). ''The Complete Catalogue Of Movie Cameras'', Hamburg/Germany, atoll medien, p. 59, Apart from those already mentioned, many very fast lenses exist in

C-mount A C mount is a type of lens mount commonly found on 16 mm movie cameras, closed-circuit television cameras, machine vision cameras and microscope phototubes. C-mount lenses provide a male thread, which mates with a female thread on the camera. ...

(as used by

16mm film 16 mm film is a historically popular and economical gauge of film. 16 mm refers to the width of the film (about inch); other common film gauges include 8 and 35 mm. It is generally used for non-theatrical (e.g., industrial, ed ...

cameras,

CCTV Closed-circuit television (CCTV), also known as video surveillance, is the use of video cameras to transmit a signal to a specific place, on a limited set of monitors. It differs from broadcast television in that the signal is not openly tr ...

, medical & scientific imaging systems), including: * Fujinon 50mm 0.7 * Canon 'TV-16' 25mm 0.78 * Fujinon YV2.7x2.9LR4A-SA 2.9-8mm 0.95 * Apollo 25mm 0.85 * Computar 8mm 0.8 (6.4 x 4.8 mm image) * Ernitec 25mm 0.85 * Fujinon 25mm 0.85 * Tarcus 25mm 0.85 *

Kern Switar KERN (1180 AM) is a commercial radio station licensed to Wasco- Greenacres, California, and serving the Bakersfield metropolitan area. The station is owned by American General Media. The radio studios and offices are in the American General M ...

18mm 0.9 (built for NASA for the Apollo Moon landing) * Ampex 'LE610 Television Lens' 25mm 0.95 * Angénieux 25mm 0.95 Type 'M1' and 'M2' (M1 was the original, more common, consumer-grade product, while M2 was aimed at the professional cine market, with better correction for aberrations and distortions) * Angénieux 28mm 0.95 Type 'M1' and 'M2' (for 16mm film) * Angénieux 35mm 0.95 * Angenieux 50mm 0.95 Type 'M1' and 'M2' * AstroScope 25mm 0.95 * Avenir 25mm 0.95 * Century 'Nighthawk' 25mm 0.95 * Carl Meyer 25mm 0.95 * Cinetar 25mm 0.95 * Goyo Optical 17mm, 25mm, and 50mm 0.95 * JML 25mm and 50mm 0.95 * Navitar 25mm and 50mm 0.95 (see also above entry to the Noktor) * Navitron 25mm and 50mm 0.95 (see also above entry to the Noktor) *

Schneider Kreuznach Schneider Kreuznach () is the abbreviated name of the company Jos. Schneider Optische Werke GmbH, which is sometimes also simply referred to as Schneider. They are a manufacturer of industrial and photographic optics. The company was founded on ...

'Xenon' 17mm, 25mm, and 50mm 0.95 * Senko 25mm and 50mm 0.95 (see also above entry to the Noktor) * Soligor 'Super Elitar' 25mm 0.95 * Som Berthiot 'Cinor' 25mm and 50mm 0.95 * Tarcus 'I.T.V. Lens' 50mm 0.95 * Precise Optics 50mm 0.95 * Kowa 50mm 0.95 * Yakumo 25mm and 50mm 0.95 * Zeika 'Nominar' 25mm 0.95 * Kaligar 'Nominar' 25mm 0.95 * Dallmeyer 25mm 0.99 (1930) * Astro Berlin 25mm 1.0 * Bausch & Lomb 29mm 1.0 * Astro Berlin 'Tachonar' 35mm and 75mm 1.0 * Carl Meyer Videostigmat 1.5" 38mm 1.0 * RTH (Rank/Taylor Hobson) Monital 130mm 1.0 made by SOPELEM in France, Super35mm cine lens Very fast lenses in D-mount for use in (Super-)8mm film and video (Hi)8 cameras: * Kern Switar 13mm 0.9 * Cinetor 'TELE-PHOTO' 37.5mm 1.0 * Walz 'TELEPHOTO' 37.5mm 1.0 * Amitar 'Telephoto' 38.1mm 1.0 * Rexer 'TELE' 38mm 1.0 * Manon 'Telephoto' 37.5mm 1.0 Very fast lenses used in X-ray machines: * Zeiss R-Biotar 100mm 0.73 *

100mm 0.73 * Canon 50mm and 65mm 0.75 * Leitz 50mm and 65mm 0.75 * De Oude Delft Rayxar 50mm, 65mm and 105mm, and allegedly 150mm 0.75 * De Oude Delft Rayxar 90mm 1.0 * Astro-Berlin Tachon 65mm 0.75 * Rodenstock XR-Heligon 42mm and 50mm 0.75 * Rodenstock XR-Heligon 68mm f/1 * Kowa 42mm and 65mm 0.75 * Carl Zeiss Jena 50mm 0.77 * Kowa 55mm 0.8 * Zeiss R-Biotar 55mm 0.85 * Lenzar Optics 184.6mm 0.9 (Photographic lens made by Lenzar Optics Corp., Riviera Beach FL, 0.9–8) * Kowa 33.5mm 0.95 * Kowa 55mm 1.0 * Rodenstock Heligon 68mm 1.0 * Canon 65mm and 90mm 1.0 * Fuji 90mm 1.0 * Kowa 90mm 1.0 * Zeiss R-Biotar 125mm 0.8

References

External links

Table of all fast lenses by focal length and image format covered.
Just how fast is that lens?
f-number doesn't directly determine focal-plane illuminance, due to light transmission losses. * {{cbignore Science of photography