Lens speed
Encyclopedia
Lens speed refers to the maximum aperture
diameter, or minimum f-number
, of a photographic lens
. A lens with a larger maximum aperture (that is, a smaller minimum f-number) is a fast lens because it delivers more light intensity (illuminance
) to the focal plane, allowing a faster shutter speed
. A smaller maximum aperture (larger minimum f-number) is "slow" because it delivers less light intensity and requires a slower shutter speed.
A lens may be referred to as "fast" or "slow" depending on its maximum aperture compared to other lenses of similar focal length
designed for a similar film format
. Lens speed given by the minimum f-number
, or alternatively maximum aperture diameter or maximum numerical aperture
, is a useful quantitative way to compare similar lenses.
Lens speed is important in taking pictures in dim light, or with long telephoto lenses. For controlling depth of field
, especially in portrait photography, lens speed is a key variable in combination with other variables such as focal length and camera format size.
Lenses may also be referred to as being "faster" or "slower" than one another using this same method. A lens with a maximum aperture of is faster than one with an aperture of 5.6, though neither is especially fast. A lens with an aperture of 1.8 is slower than a lens with an aperture of 1.2, though both are fast lenses.
The range of lenses considered "fast" has evolved to lower f-numbers over the years, due to advances in lens design, optical manufacturing, quality of glass, optical coating
s, and the move toward smaller imaging formats. For example, the 1911 Encyclopaedia Britannica states that "...[Lenses] are 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."
With 35 mm cameras, the fastest lenses are typically in the "normal lens
" range near 50 mm. Longer telephoto designs and wide-angle retrofocus designs tend to be slower. Attaining maximum lens speed requires engineering tradeoffs, and as such, "prime
" (fixed focal length) lenses are generally faster than zoom lens
es, and modern manual-focus lenses are generally faster than their autofocus counterparts.
The fastest lenses in general production are 1.2 or 1.4, with more at 1.8 and 2.0, and many at 2.8 or slower; 1.0 is unusual, though sees some use.
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. This is not a hard and fast rule, however, as there are several high-quality fast lenses available that are relatively inexpensive, particularly in normal lens
focal lengths. For example, the Canon EF 50mm f/1.8 II is very inexpensive, but quite fast and optically well-regarded.
): 1.0 is about 50% faster than 1.2, which is about 50% faster than 1.4.
, Canon, Nikon and Pentax all make an autofocus 50mm 1.4 lens. These are not unusual lenses and are relatively inexpensive. Canon also makes autofocus 50mm and 85mm 1.2 lenses, while Nikon makes a manual focus 50mm 1.2 lens and an autofocus 85mm 1.4; see Canon EF 50mm lens
es and Canon EF 85mm lens
es for details. Pentax makes a 77mm 1.8 lens; see Pentax lenses
.
For historical background, see .
Some of the fastest camera lenses currently in production are as follows:
The following camera lenses are no longer in production :
Many very fast lenses exist in C-mount (such as used by CCTVs), including:
Very fast lenses in D-mount for 8mm movie use on H8 cameras:
Very fast lenses used in x-ray machines:
Aperture
In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture of an optical system is the opening that determines the cone angle of a bundle of rays that come to a focus in the image plane. The aperture determines how collimated the admitted rays are,...
diameter, or minimum f-number
F-number
In optics, the f-number of an optical system expresses the diameter of the entrance pupil in terms of the focal length of the lens; in simpler terms, the f-number is the focal length divided by the "effective" aperture diameter...
, of a photographic lens
Photographic lens
A camera lens 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 capable of storing an image chemically or electronically.While in principle a simple convex lens will suffice, in...
. A lens with a larger maximum aperture (that is, a smaller minimum f-number) is a fast lens because it delivers more light intensity (illuminance
Illuminance
In photometry, illuminance is the total luminous flux incident on a surface, per unit area. It is a measure of the intensity of the incident light, wavelength-weighted by the luminosity function to correlate with human brightness perception. Similarly, luminous emittance is the luminous flux per...
) to the focal plane, allowing a faster shutter speed
Shutter speed
In photography, shutter speed is a common term used to discuss exposure time, the effective length of time a camera's shutter is open....
. A smaller maximum aperture (larger minimum f-number) is "slow" because it delivers less light intensity and requires a slower shutter speed.
A lens may be referred to as "fast" or "slow" depending on its maximum aperture compared to other lenses of similar focal length
Focal length
The focal length of an optical system is a measure of how strongly the system converges or diverges light. For an optical system in air, it is the distance over which initially collimated rays are brought to a focus...
designed for a similar film format
Film format
A film format is a technical definition of a set of standard characteristics regarding image capture on photographic film, for either stills or movies. It can also apply to projected film, either slides or movies. The primary characteristic of a film format is its size and shape.In the case of...
. Lens speed given by the minimum f-number
F-number
In optics, the f-number of an optical system expresses the diameter of the entrance pupil in terms of the focal length of the lens; in simpler terms, the f-number is the focal length divided by the "effective" aperture diameter...
, or alternatively maximum aperture diameter or maximum numerical aperture
Numerical aperture
In optics, the numerical aperture 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 property that it is constant for a beam as it goes from one...
, is a useful quantitative way to compare similar lenses.
Lens speed is important in taking pictures in dim light, or with long telephoto lenses. For controlling depth of field
Depth of field
In optics, particularly as it relates to film and photography, depth of field is the distance between the nearest and farthest objects in a scene that appear acceptably sharp in an image...
, especially in portrait photography, lens speed is a key variable in combination with other variables such as focal length and camera format size.
Lenses may also be referred to as being "faster" or "slower" than one another using this same method. A lens with a maximum aperture of is faster than one with an aperture of 5.6, though neither is especially fast. A lens with an aperture of 1.8 is slower than a lens with an aperture of 1.2, though both are fast lenses.
The range of lenses considered "fast" has evolved to lower f-numbers over the years, due to advances in lens design, optical manufacturing, quality of glass, optical coating
Optical coating
An optical coating is one or more thin layers of material deposited on an optical component such as a lens or mirror, which alters the way in which the optic reflects and transmits light. One type of optical coating is an antireflection coating, which reduces unwanted reflections from surfaces, and...
s, and the move toward smaller imaging formats. For example, the 1911 Encyclopaedia Britannica states that "...[Lenses] are 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."
With 35 mm cameras, the fastest lenses are typically in the "normal lens
Normal lens
In photography and cinematography a normal lens, also called a standard lens, is a lens that reproduces perspective that generally looks "natural" to a human observer under normal viewing conditions, as compared with lenses with longer or shorter focal lengths which produce an expanded or...
" range near 50 mm. Longer telephoto designs and wide-angle retrofocus designs tend to be slower. Attaining maximum lens speed requires engineering tradeoffs, and as such, "prime
Prime lens
In film and photography, a prime lens is either a photographic lens whose focal length is fixed, as opposed to a zoom lens, or it is the primary lens in a combination lens system....
" (fixed focal length) lenses are generally faster than zoom lens
Zoom lens
A zoom lens is a mechanical assembly of lens elements for which the focal length can be varied, as opposed to a fixed focal length lens...
es, and modern manual-focus lenses are generally faster than their autofocus counterparts.
The fastest lenses in general production are 1.2 or 1.4, with more at 1.8 and 2.0, and many at 2.8 or slower; 1.0 is unusual, though sees some use.
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. This is not a hard and fast rule, however, as there are several high-quality fast lenses available that are relatively inexpensive, particularly in normal lens
Normal lens
In photography and cinematography a normal lens, also called a standard lens, is a lens that reproduces perspective that generally looks "natural" to a human observer under normal viewing conditions, as compared with lenses with longer or shorter focal lengths which produce an expanded or...
focal lengths. For example, the Canon EF 50mm f/1.8 II is very inexpensive, but quite fast and optically well-regarded.
Fast lenses
For scale, note that 0.7, 1.0, 1.4, and 2.0 are each 1 f-stop apart (2× as fast), as an f-stop correspond to a factor of square root of 2, about 1.4. Thus around 1.0, a change of 0.1 corresponds to about 1/4 of an f-stop (by linear approximationLinear approximation
In mathematics, a linear approximation is an approximation of a general function using a linear function . They are widely used in the method of finite differences to produce first order methods for solving or approximating solutions to equations.-Definition:Given a twice continuously...
): 1.0 is about 50% faster than 1.2, which is about 50% faster than 1.4.
, Canon, Nikon and Pentax all make an autofocus 50mm 1.4 lens. These are not unusual lenses and are relatively inexpensive. Canon also makes autofocus 50mm and 85mm 1.2 lenses, while Nikon makes a manual focus 50mm 1.2 lens and an autofocus 85mm 1.4; see Canon EF 50mm lens
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 between element 2 and 3 and its faster cousins adding...
es and Canon EF 85mm lens
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....
es for details. Pentax makes a 77mm 1.8 lens; see Pentax lenses
Pentax Lenses
Pentax DA and DA* lenses are the current lens line for Pentax digital SLR cameras. They use the Pentax KAF Mount. All of these lenses have an autofocus feature, either operated from the camera body or from an internal SDM motor...
.
For historical background, see .
Some of the fastest camera lenses currently in production are as follows:
- Cosina VoigtländerCosina VoigtländerCosina Voigtländer refers to photographic products manufactured by Cosina under the Voigtländer name since 1999. Cosina leases rights to the Voigtländer name from Ringfoto...
Nokton 25mm 0.95 (Micro Four ThirdsMicro Four Thirds systemThe Micro Four Thirds system is a standard created by Olympus and Panasonic, and announced on August 5, 2008, for mirrorless interchangeable lens digital cameras and camcorders design and development...
mount, announced 26/8/2010) - Leica Noctilux-M 50 mm f/0.95 ASPH, announced on September 15, 2008, it is the fastest aspherical lens to have ever reached mass production, with a MSRP of £6290 (aprox $10,000USD).
- NoktorNoktorNoktor is a manufacturer of a 50mm 0.95 HyperPrime manual-focus lens for the Micro Four Thirds system. Noktor's lenses went on sale in April 2010, and they are one of three types of lenses faster than 1.0 that are currently manufactured.-External links:*...
50mm 0.95 'HyperPrime' (a fast CCTV lens design adapted for the Micro Four Thirds systemMicro Four Thirds systemThe Micro Four Thirds system is a standard created by Olympus and Panasonic, and announced on August 5, 2008, for mirrorless interchangeable lens digital cameras and camcorders design and development...
)
The following camera lenses are no longer in production :
- Zeiss 50mm 0.7 (Limited production lens built for the NASANASAThe National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
space program, used on 35mm movie cameras by Stanley KubrickStanley KubrickStanley Kubrick was an American film director, writer, producer, and photographer who lived in England during most of the last four decades of his career...
for some candlelit scenes in Barry LyndonBarry LyndonBarry Lyndon is a 1975 British-American period romantic war film produced, written, and directed by Stanley Kubrick based on the 1844 novel The Luck of Barry Lyndon by William Makepeace Thackeray which recounts the exploits of an 18th century Irish adventurer...
) - Tokyo KogakuTopconTopcon is a Japanese manufacturer of optical equipment for ophthalmology and surveying. Their headquarters are in Itabashi, Tokyo. They are affiliated with Toshiba, which holds 40% of Topcon's stock.-History of Topcon:...
Similar 50 mm 0.7 (WWII) and Similar 5 cm 0.7 (1951; only three were produced, two of which were used on a South PoleSouth PoleThe South Pole, also known as the Geographic South Pole or Terrestrial South Pole, is one of the two points where the Earth's axis of rotation intersects its surface. It is the southernmost point on the surface of the Earth and lies on the opposite side of the Earth from the North Pole...
expedition) - WrayWrayWray or WRAY may refer to:* Wray , former British camera and lens manufacturer* Wray, Colorado, city in Yuma County, Colorado, USA* Wray, Lancashire, village of Lancashire, England...
64mm 0.71 - Leica Leitz 75mm 0.85
- NikonNikon, also known as just Nikon, is a multinational corporation headquartered in Tokyo, Japan, specializing in optics and imaging. Its products include cameras, binoculars, microscopes, measurement instruments, and the steppers used in the photolithography steps of semiconductor fabrication, of which...
TV-Nikkor 35mm 0.9-Fastest Nikon lens ever made - CanonCanon Inc.is a Japanese multinational corporation that specialises in the manufacture of imaging and optical products, including cameras, camcorders, photocopiers, steppers and computer printers. Its headquarters are located in Ōta, Tokyo, Japan.-Origins:...
50mm 0.95 (Available in TV and Canon 7 Rangefinder Version) - Leica ELCAN 90mm 1.0
- Leica Noctilux 50mm 1.0 (Leica M mount, discontinued and replaced 2008 with a new Noctilux, see above)
- Canon EFCanon EF lens mountIntroduced in 1987, the EF lens mount is the standard lens mount on the Canon EOS family of SLR film and digital cameras. EF stands for "Electro-Focus": automatic focusing on EF lenses is handled by a dedicated electric motor built into the lens...
50mm 1.0 (for Canon autofocus SLR, now out of production) - CanonCanon Inc.is a Japanese multinational corporation that specialises in the manufacture of imaging and optical products, including cameras, camcorders, photocopiers, steppers and computer printers. Its headquarters are located in Ōta, Tokyo, Japan.-Origins:...
8.5-25.5 mm 1.0 zoom lens, made 1975-1983 for the 310XL Super 8mmSuper 8 mm filmSuper 8 mm film is a motion picture film format released in 1965 by Eastman Kodak as an improvement of the older "Double" or "Regular" 8 mm home movie format....
silent and sound camera series, fastest lens ever made in Super8, was originally advertised as facilitating "shooting at candlelight" in combination with 160-ASA films.
Many very fast lenses exist in C-mount (such as used by CCTVs), including:
- FujinonFujinonFujinon is a division of Fujifilm that specialises in the production of optical lenses for photographic, medical, video, and television use.- Fujinon SWD :...
50mm 0.7 - Canon 'TV-16' 25mm 0.78
- Apollo 'High Speed Lens' 25mm 0.85
- FujinonFujinonFujinon is a division of Fujifilm that specialises in the production of optical lenses for photographic, medical, video, and television use.- Fujinon SWD :...
25mm 0.85 - Tarcus 25mm 0.85
- Ampex 'LE610 Television Lens' 25mm 0.95
- Angenieux 'M1' and 'M2' 25mm 0.95 (NASA used the M1 for first high-resolution photographs of the Moon by Ranger 7Ranger 7Ranger 7 was the first US space probe to successfully transmit close images of the lunar surface back to Earth. It was also the first completely successful flight of the Ranger program. Launched on 28 July 1964, Ranger 7 was designed to achieve a lunar impact trajectory and to transmit...
) - Angenieux 50mm 0.95
- AstroScope 25mm 0.95
- Avenir 25mm 0.95
- Century 'Nighthawk' 25mm 0.95
- Carl Meyer 25mm 0.95
- Cinetar 25mm 0.95
- Dallmeyer 25mm 0.99 (1930)
- Goyo Optical 17mm, 25mm, and 50mm 0.95
- JML 25mm and 50mm 0.95
- Navitar 25mm and 50mm 0.95
- Navitron 25mm and 50mm 0.95
- Schneider KreuznachSchneider KreuznachSchneider 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....
'Xenon' 17mm, 25mm, and 50mm 0.95 - Senko 25mm and 50mm 0.95
- SoligorSoligorSoligor 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...
'Super Elitar' 25mm 0.95 - Som Berthiot 'Cinor' 25mm and 50mm 0.95
- Tarcus 'I.T.V. Lens' 50mm 0.95
- Yakumo 25mm and 50mm 0.95
- Zeika 'Nominar' 25mm 0.95
- Astro Berlin 25mm 1.0
- Astro Berlin 'Tachonar' 35mm 1.0
- Carl Meyer 38mm 1.0
- RTH (Rank/Taylor Hobson) Monital 130mm 1.0 (made by SOPELEM in France)
Very fast lenses in D-mount for 8mm movie use on H8 cameras:
- Kern Switar 13mm 0.9
- Kern Switar 18mm 0.9 (built for NASA for Apollo Moon landing)
- Cinetor 'TELE-PHOTO' 37.5mm 1.0
- Walz 'TELEPHOTO' 37.5mm 1.0
Very fast lenses used in x-ray machines:
- Canon 50mm/65mm 0.75
- Leitz 50mm/65mm 0.75
- Rayxar 50mm/65mm/150mm 0.75
- Tachon Astro-Berlin 65mm 0.75
- RodenstockRodenstock GmbHThe Rodenstock GmbH is a renowned German manufacturer headquartered in Munich and the only brand producer of the entire spectacles product worldwide...
TV-Heligon 42mm/50mm 0.75 - RodenstockRodenstock GmbHThe Rodenstock GmbH is a renowned German manufacturer headquartered in Munich and the only brand producer of the entire spectacles product worldwide...
XR-Heligon 42mm/50mm 0.75 - Kowa 42mm/65mm 0.75
- Kowa 55mm 0.8
- Lenzar Optics 184.6mm 0.9 (Photographic lens made by Lenzar Optics Corp., Riviera Beach FL, f0.9-f8)
- Kowa 33.5mm 0.95
- Canon 90mm 1.0
- FujiFujifilmis a multinational photography and imaging company headquartered in Tokyo, Japan.Fujifilm's principal activities are the development, production, sale and servicing of color photographic film, digital cameras, photofinishing equipment, color paper, photofinishing chemicals, medical imaging...
90mm 1.0 - Kowa 90mm 1.0
- Leitz 90mm 1.0
- RodenstockRodenstock GmbHThe Rodenstock GmbH is a renowned German manufacturer headquartered in Munich and the only brand producer of the entire spectacles product worldwide...
Heligon 68mm 1.0 - Kowa 55mm 1.0
- Mt Prospect 90mm 1.0
External links
- Just how fast is that lens? f-number doesn't directly determine focal-plane illuminance, due to light transmission losses.