Lens speed refers to the maximum aperture diameter, or minimum f-number, of a photographic lens. 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 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 dist ...

and bokeh, especially in portrait photography, as well as for sports photography 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 (such ...

. 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" (fixed focal length) lenses are generally faster than

zoom lens A zoom lens is a mechanical assembly of lens elements for which the focal length (and thus angle of view) can be varied, as opposed to a fixed-focal-length (FFL) lens (see prime lens). A true zoom lens, also called a parfocal lens, is one ...

es. 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 optical aberration, aberration found in optical systems that have elements with spherical surfaces. Lens (optics), Lenses and curved mirrors are prime examples, because this shape is easier to man ...

becomes more significant and must be corrected. Thus, faster telephoto and wide-angle retrofocus designs tend to be much more expensive. A

telecompressor A telecompressor or focal reducer is an optical element used to reduce focal length, increase lens speed, and in some instances improve optical transfer function (OTF) performance. It is also widely known under the name “Speed Booster”, which is ...

, 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 coating An optical coating is one or more thin layers of material deposited on an optical component such as a lens, prism or mirror, which alters the way in which the optic reflects and transmits light. These coatings have become a key technology in th ...

s, and the move toward smaller imaging formats. For example, the

1911 Encyclopædia Britannica A notable ongoing event was the Comparison of the Amundsen and Scott Expeditions, race for the South Pole. Events January * January 1 – A decade after federation, the Northern Territory and the Australian Capital Territory ...

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 princip ...

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

cameras; see Pentax lenses. 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 system. In 2014, Panasonic 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 displayed a prop lens christened the Super-Q-Gigantar 40mm 0.33 at photokina. 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 In optics, the numerical aperture (NA) of an optical system is a dimensionless number that characterizes the range of angles over which the system can accept or emit light. By incorporating index of refraction in its definition, NA has the proper ...

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 is ...

diameter. In practice, that cannot be reached due to mechanical constraints of the camera system (shutter clearance,

mount Mount is often used as part of the name of specific mountains, e.g. Mount Everest. Mount or Mounts may also refer to: Places * Mount, Cornwall, a village in Warleggan parish, England * Mount, Perranzabuloe, a hamlet in Perranzabuloe parish, C ...

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, to protect ...

systems), the cost of going beyond a numerical aperture of 0.95 (f/0.164) is usually prohibitive. In SLR camera systems, typical

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 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 Cosina Voigtländer refers to photographic products manufactured by Cosina under the Voigtländer name since 1999. Cosina leases rights to the Voigtländer name from RINGFOTO GmbH & Co. ALFO Marketing KG in Germany. Cosina Voigtländer products have ...

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 *

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 Fujinon is a brand of optical lenses made by Fuji Photo Film Co., Ltd, now known as Fujifilm. Fujifilm's Fujinon lenses have been used by professional photographers and broadcast stations as well as cinematography. Fujifilm started manufacture ...

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 The American Optical Company, also known as AO Eyewear, is a luxury American eyewear and sunglass company based in Vernon Hills, Illinois near Chicago. AO designs and manufactures in the United States. History Founded in 1833 by William Beecher, ...

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 *

-IDEAX 125mm 0.67 and/or 0.85 (X-ray lens, two speeds quoted on front ring) *

Zeiss Zeiss or Zeiß may refer to: People *Carl Zeiss (1816–1888), German optician and entrepreneur *Emil Zeiß (1833–1910), German Protestant minister and painter Companies *Carl Zeiss AG, German manufacturer of optics, industrial measurem ...

Planar 50mm 0.7 (Limited 10-copies production for the NASA 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 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 Magee, Leonard ...

'') * 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 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 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 *

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 Super Farron 76mm 0.87 * Farrand 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 TV-Nikkor 35mm 0.9 (Fastest Nikon lens ever made; TV lens in M39 lens mount, 12.6 mm diameter image circle) *

Noktor Noktor was a manufacturer of a 50mm 0.95 HyperPrime manual-focus lens A lens is a transmissive optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, w ...

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 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 Reconar 98mm 1.0 Medium Format aerial photography lens * Kollmorgen 153mm 1.0 *

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, educ ...

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 t ...

, medical & scientific imaging systems), including: *

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 *

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 Angénieux is a French manufacturer of photographic and cinematographic lenses. The main markets are cinema, television, space travel and medicine. The company is part of the Thales Group, which represents Angénieux in 48 countries. The company ...

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) *

28mm 0.95 Type 'M1' and 'M2' (for 16mm film) *

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 'Xenon' 17mm, 25mm, and 50mm 0.95 * Senko 25mm and 50mm 0.95 (see also above entry to the Noktor) *

Soligor Soligor was originally the trade mark for the American Allied Impex Corporation, used from 1956 for lenses and later cameras imported from Japan. It imported cameras from Japan and also took control of companies in Japan. Among the first product ...

'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: *

R-Biotar 100mm 0.73 * LOMO 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 *

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 *

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