Large format lens
Encyclopedia
Large format lenses are photograph
Photograph
A photograph is an image created by light falling on a light-sensitive surface, usually photographic film or an electronic imager such as a CCD or a CMOS chip. Most photographs are created using a camera, which uses a lens to focus the scene's visible wavelengths of light into a reproduction of...
ic optic
Optic
Optic may mean:* optic, a British term for a device for dispensing fixed amounts of alcoholic spirits* Optics, the study of the behavior and properties of light* An optical element or component, such as a lens, prism, or mirror...
s that provide an image circle
Image circle
The image circle, or circle of illumination, of a lens is the circular area in the image plane formed by the cone of light transmitted by the lens . Within this circle is the smaller circle for which image definition is acceptable, the circle of good definition ; however, some authors make no...
large enough to cover large format film
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...
or plates
Photographic plate
Photographic plates preceded photographic film as a means of photography. A light-sensitive emulsion of silver salts was applied to a glass plate. This form of photographic material largely faded from the consumer market in the early years of the 20th century, as more convenient and less fragile...
. Large format lenses are typically used in large format
Large format
Large format refers to any imaging format of 4×5 inches or larger. Large format is larger than "medium format", the 6×6 cm or 6×9 cm size of Hasselblad, Rollei, Kowa, Pentax etc cameras , and much larger than the 24×36 mm frame of 35 mm format.The main advantage...
cameras and view camera
View camera
The view camera is a type of camera first developed in the era of the Daguerreotype and still in use today, though with many refinements. It comprises a flexible bellows which forms a light-tight seal between two adjustable standards, one of which holds a lens, and the other a viewfinder or a...
s.
Photographic optics generally project a circular image behind the lens
Lens (optics)
A lens is an optical device with perfect or approximate axial symmetry which transmits and refracts light, converging or diverging the beam. A simple lens consists of a single optical element...
. On smaller format cameras the image circle generally covers only the intended film size with little room to spare. Large format lenses are an exception. For large format use the circular patch of image light usually extends beyond the minimum size circle needed to fully cover the rectangle of the film. The extra image offers some or a great deal of room to spare since large format cameras usually make use of camera movements that re-align the lens away from dead center on the film. The film is often positioned as far off center as just inside the periphery of the image circle.
Lens designs
Lenses of the same general construction are often given a name implying this design. For example, a Tessar always has four elements in three groups as described below, although Tessars have been produced with different focal lengths and maximum apertures for many decades. Sometimes a name does not identify a specific design; Kodak's Ektar lens brand name encompasses many different types. Sometimes different manufacturers use different names for lenses of the same type; for example the Voigtländer Skopar is of Tessar design. And sometimes identical lenses are sold under different names and at different prices; for example, lenses branded as Rodenstock and Caltar.Early lenses suffered from flare and low contrast, worsening as the number of lens-air interfaces increased. The introduction of and improvements in anti-reflective coating
Anti-reflective coating
An antireflective or anti-reflection coating is a type of optical coating applied to the surface of lenses and other optical devices to reduce reflection. This improves the efficiency of the system since less light is lost. In complex systems such as a telescope, the reduction in reflections also...
s vastly reduced flare; some many-element lens designs which had been abandoned due to low contrast in spite of otherwise excellent performance became practical.
Lenses designed for use with monochromatic film, first orthochromatic
Orthochromatic
- Orthochromatic photography :Orthochromatic photography refers to a photographic emulsion that is sensitive to only blue and green light, and thus can be processed with a red safelight. The increased blue sensitivity causes blue objects to appear lighter and red ones darker...
, then panchromatic
Panchromatic
Panchromatic film is a type of black-and-white photographic film that is sensitive to all wavelengths of visible light. A panchromatic film therefore produces a realistic reproduction of a scene as it appears to the human eye. Almost all modern photographic film is panchromatic, but some types are...
, had less exacting requirements regarding chromatic aberrations than when colour film is used. When using older lenses today one should check that chromatic aberrations and flare are acceptable for the application.
Wide-angle lens designs
- The Hypergon is a wide angle lens that covers a flat field. It is constructed symmetrically consisting of two deep meniscusMeniscusThe meniscus is the curve in the upper surface of a liquid close to the surface of the container or another object, caused by surface tension. It can be either convex or concave. A convex meniscus occurs when the molecules have a stronger attraction to each other than to the material of the...
elements that almost form a sphereSphereA sphere is a perfectly round geometrical object in three-dimensional space, such as the shape of a round ball. Like a circle in two dimensions, a perfect sphere is completely symmetrical around its center, with all points on the surface lying the same distance r from the center point...
. The apertureApertureIn 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,...
is limited to f/20 due to sphericalSpherical aberrationthumb|right|Spherical aberration. A perfect lens focuses all incoming rays to a point on the [[Optical axis|optic axis]]. A real lens with spherical surfaces suffers from spherical aberration: it focuses rays more tightly if they enter it far from the optic axis than if they enter closer to the...
and chromatic aberrationChromatic aberrationIn optics, chromatic aberration is a type of distortion in which there is a failure of a lens to focus all colors to the same convergence point. It occurs because lenses have a different refractive index for different wavelengths of light...
s. - The Topogon is a double Gauss design arranged in a symmetrical design. Due to its wide angle coverage, and the small distortion, it and the MetrogonMetrogonMetrogon is a high resolution, low-distortion, extra-wide field photographic lens design, popularized by Bausch and Lomb. Variations of this design are said to have been used extensively by the US military for use in aerial photography on the T-11 camera .The most common Metrogon lenses have a f...
became the standard aerial lens until it was displaced in 1952. - The Hologon is a modification of the Biogon lens design. It contains a rear element that is close to film planeFilm planeA film plane is the area inside any image taking device with a lens and a digital sensor or film; such as a camera. The film plane varies in distance from the lens focal point in each manufacturer...
for better contrast, but interferes with mirror for SLRSingle-lens reflex cameraA single-lens reflex camera is a camera that typically uses a semi-automatic moving mirror system that permits the photographer to see exactly what will be captured by the film or digital imaging system, as opposed to pre-SLR cameras where the view through the viewfinder could be significantly...
. There is significant light falloff at edges, so it is frequently used with ND center graduated filters. - The Biogon is an ultra-wide-angle design by Ludwig BerteleLudwig BerteleLudwig Jakob Bertele was a German optics constructor. His developments received universal recognition and serve as a basis for considerable part of optical designs, which are used in modern world.-Biography:...
based on a double-ended reversed-telephoto objective. It was made by Zeiss for their 35mm ContaxContaxContax was a camera brand noted for its unique technical innovation and a wide range of Zeiss lenses, noted for their high optical quality. Its final incarnation was a line of 35 mm, medium format and digital cameras engineered and manufactured by Kyocera, and featuring modern Zeiss optics...
and the medium-format HasselbladHasselbladVictor Hasselblad AB is a Swedish manufacturer of medium-format cameras and photographic equipment based in Gothenburg, Sweden.The company is best known for the medium-format cameras it has produced since World War II....
cameras. The design was physically large, being two focal lengths in length and one focal length in diameter. There are two menisci at the front, and a single strong meniscus element at the rear. The rear element is close to the film plane for low distortion and better contrast, but interferes with the mirror on a single-lens reflex camera. - The Goerz Dagor has two symmetrical cemented triplets (6 elements in 2 groups). The two outer elements are positive, one of the inner elements is used to correct spherical aberration, and the other to flatten the field. There are only 4 glass-to-air interfaces, giving better flare and contrast than lenses with more elements, particularly important before the introduction of coated lenses. Reputed to have good sharpness and a large image circle, although there is softness at the edges.
File:Hypergon.png|Hypergon
File:Topogon.png|Topogon
File:Hologon.png|Hologon
File:Biogon21.png|Biogon
File:Dagor.png|Dagor
Normal lens designs
- Anastigmat is an achromatic lensAchromatic lensAn achromatic lens or achromat is a lens that is designed to limit the effects of chromatic and spherical aberration. Achromatic lenses are corrected to bring two wavelengths into focus in the same plane....
used to reduce or eliminate astigmatismAstigmatismAn optical system with astigmatism is one where rays that propagate in two perpendicular planes have different foci. If an optical system with astigmatism is used to form an image of a cross, the vertical and horizontal lines will be in sharp focus at two different distances...
designed specifically for photographic applications. All modern lenses are anastigmatic; lenses produced in the early days when this was a new feature often had the word Anastigmat in their name: Voigtländer Anastigmat Skopar.
- A TessarTessarThe Tessar is a famous photographic lens design conceived by physicist Paul Rudolph in 1902 while he worked at the Zeiss optical company and patented by Zeiss; the lens type is usually known as the Zeiss Tessar....
comprises four elements in three groups, one positive crown glassCrown glassCrown glass is either of two kinds of glass:*Crown glass was a type of hand-blown window glass.*Crown glass is a type of optical glass used in lenses....
element on the front, one negative flint glassFlint glassFlint glass is optical glass that has relatively high refractive index and low Abbe number. Flint glasses are arbitrarily defined as having an Abbe number of 50 to 55 or less. The currently known flint glasses have refractive indices ranging between 1.45 and 2.00...
element at the center and a negative plano-concave flint glass element cemented with a positive convex crown glass element at the rear. Many manufacturers have produced lenses of this type under their own names.
The Tessar design is suitable for front-element focussing, but unit focussing is used on large format cameras.
- The Heliar design consists of 5 elements in three groups with cemented doublets, allowing correction of spherical, chromatic, and astigmatic aberrations.
- A PlanarZeiss PlanarThe Zeiss Planar is a photographic lens designed by Paul Rudolph at Carl Zeiss in 1896. Rudolph's original was a six-element symmetrical design....
design is one with 4 groups of 6 elements, and a flat field design. Its symmetrical optical configuration produces low spherical aberration and astigmatism. The design was not widely used until coating processes were available, due to the very low contrast caused by light loss from the large number of transmission surfaces. - The SonnarZeiss SonnarThe Sonnar is a photographic lens originally designed by Dr. Ludwig Bertele in 1924 and patented by Zeiss Ikon. It was notable for its relatively light weight, simple design and fast aperture. The name "Sonnar" is derived from the German word "Sonne", meaning sun...
design originally had six elements, later seven, in three groups. The design uses fewer elements than the Planar design and is smaller and less expensive. It has more aberrations but better contrast and less flare than the Planar, a larger maximum aperture and lower chromatic aberration than the Tessar. Large format Sonnars have good sharpness and contrast at large apertures, but are large and heavy, and coverage does not allow much use of movements. The Sonnar has good edge contrastContrast (vision)Contrast is the difference in visual properties that makes an object distinguishable from other objects and the background. In visual perception of the real world, contrast is determined by the difference in the color and brightness of the object and other objects within the same field of view...
at all apertures, but some softness at wide apertures. - The Artar is a true apochromatic 4-element in 4 groups symmetrical process lens for the graphic arts, very well corrected for other aberrations. It was designed by Walter Zschokke of Goerz in 1904, based on Emile Von Hoegh's dialytehttp://www.panix.com/~zone/photo/czlens.htm. If uncoated it is subject to flare due to the 8 air-to-glass surfaces.
Large format lenses are photograph
Photograph
A photograph is an image created by light falling on a light-sensitive surface, usually photographic film or an electronic imager such as a CCD or a CMOS chip. Most photographs are created using a camera, which uses a lens to focus the scene's visible wavelengths of light into a reproduction of...
ic optic
Optic
Optic may mean:* optic, a British term for a device for dispensing fixed amounts of alcoholic spirits* Optics, the study of the behavior and properties of light* An optical element or component, such as a lens, prism, or mirror...
s that provide an image circle
Image circle
The image circle, or circle of illumination, of a lens is the circular area in the image plane formed by the cone of light transmitted by the lens . Within this circle is the smaller circle for which image definition is acceptable, the circle of good definition ; however, some authors make no...
large enough to cover large format film
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...
or plates
Photographic plate
Photographic plates preceded photographic film as a means of photography. A light-sensitive emulsion of silver salts was applied to a glass plate. This form of photographic material largely faded from the consumer market in the early years of the 20th century, as more convenient and less fragile...
. Large format lenses are typically used in large format
Large format
Large format refers to any imaging format of 4×5 inches or larger. Large format is larger than "medium format", the 6×6 cm or 6×9 cm size of Hasselblad, Rollei, Kowa, Pentax etc cameras , and much larger than the 24×36 mm frame of 35 mm format.The main advantage...
cameras and view camera
View camera
The view camera is a type of camera first developed in the era of the Daguerreotype and still in use today, though with many refinements. It comprises a flexible bellows which forms a light-tight seal between two adjustable standards, one of which holds a lens, and the other a viewfinder or a...
s.
Photographic optics generally project a circular image behind the lens
Lens (optics)
A lens is an optical device with perfect or approximate axial symmetry which transmits and refracts light, converging or diverging the beam. A simple lens consists of a single optical element...
. On smaller format cameras the image circle generally covers only the intended film size with little room to spare. Large format lenses are an exception. For large format use the circular patch of image light usually extends beyond the minimum size circle needed to fully cover the rectangle of the film. The extra image offers some or a great deal of room to spare since large format cameras usually make use of camera movements that re-align the lens away from dead center on the film. The film is often positioned as far off center as just inside the periphery of the image circle.
Lens designs
Lenses of the same general construction are often given a name implying this design. For example, a Tessar always has four elements in three groups as described below, although Tessars have been produced with different focal lengths and maximum apertures for many decades. Sometimes a name does not identify a specific design; Kodak's Ektar lens brand name encompasses many different types. Sometimes different manufacturers use different names for lenses of the same type; for example the Voigtländer Skopar is of Tessar design. And sometimes identical lenses are sold under different names and at different prices; for example, lenses branded as Rodenstock and Caltar.Early lenses suffered from flare and low contrast, worsening as the number of lens-air interfaces increased. The introduction of and improvements in anti-reflective coating
Anti-reflective coating
An antireflective or anti-reflection coating is a type of optical coating applied to the surface of lenses and other optical devices to reduce reflection. This improves the efficiency of the system since less light is lost. In complex systems such as a telescope, the reduction in reflections also...
s vastly reduced flare; some many-element lens designs which had been abandoned due to low contrast in spite of otherwise excellent performance became practical.
Lenses designed for use with monochromatic film, first orthochromatic
Orthochromatic
- Orthochromatic photography :Orthochromatic photography refers to a photographic emulsion that is sensitive to only blue and green light, and thus can be processed with a red safelight. The increased blue sensitivity causes blue objects to appear lighter and red ones darker...
, then panchromatic
Panchromatic
Panchromatic film is a type of black-and-white photographic film that is sensitive to all wavelengths of visible light. A panchromatic film therefore produces a realistic reproduction of a scene as it appears to the human eye. Almost all modern photographic film is panchromatic, but some types are...
, had less exacting requirements regarding chromatic aberrations than when colour film is used. When using older lenses today one should check that chromatic aberrations and flare are acceptable for the application.
Wide-angle lens designs
- The Hypergon is a wide angle lens that covers a flat field. It is constructed symmetrically consisting of two deep meniscusMeniscusThe meniscus is the curve in the upper surface of a liquid close to the surface of the container or another object, caused by surface tension. It can be either convex or concave. A convex meniscus occurs when the molecules have a stronger attraction to each other than to the material of the...
elements that almost form a sphereSphereA sphere is a perfectly round geometrical object in three-dimensional space, such as the shape of a round ball. Like a circle in two dimensions, a perfect sphere is completely symmetrical around its center, with all points on the surface lying the same distance r from the center point...
. The apertureApertureIn 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,...
is limited to f/20 due to sphericalSpherical aberrationthumb|right|Spherical aberration. A perfect lens focuses all incoming rays to a point on the [[Optical axis|optic axis]]. A real lens with spherical surfaces suffers from spherical aberration: it focuses rays more tightly if they enter it far from the optic axis than if they enter closer to the...
and chromatic aberrationChromatic aberrationIn optics, chromatic aberration is a type of distortion in which there is a failure of a lens to focus all colors to the same convergence point. It occurs because lenses have a different refractive index for different wavelengths of light...
s. - The Topogon is a double Gauss design arranged in a symmetrical design. Due to its wide angle coverage, and the small distortion, it and the MetrogonMetrogonMetrogon is a high resolution, low-distortion, extra-wide field photographic lens design, popularized by Bausch and Lomb. Variations of this design are said to have been used extensively by the US military for use in aerial photography on the T-11 camera .The most common Metrogon lenses have a f...
became the standard aerial lens until it was displaced in 1952. - The Hologon is a modification of the Biogon lens design. It contains a rear element that is close to film planeFilm planeA film plane is the area inside any image taking device with a lens and a digital sensor or film; such as a camera. The film plane varies in distance from the lens focal point in each manufacturer...
for better contrast, but interferes with mirror for SLRSingle-lens reflex cameraA single-lens reflex camera is a camera that typically uses a semi-automatic moving mirror system that permits the photographer to see exactly what will be captured by the film or digital imaging system, as opposed to pre-SLR cameras where the view through the viewfinder could be significantly...
. There is significant light falloff at edges, so it is frequently used with ND center graduated filters. - The Biogon is an ultra-wide-angle design by Ludwig BerteleLudwig BerteleLudwig Jakob Bertele was a German optics constructor. His developments received universal recognition and serve as a basis for considerable part of optical designs, which are used in modern world.-Biography:...
based on a double-ended reversed-telephoto objective. It was made by Zeiss for their 35mm ContaxContaxContax was a camera brand noted for its unique technical innovation and a wide range of Zeiss lenses, noted for their high optical quality. Its final incarnation was a line of 35 mm, medium format and digital cameras engineered and manufactured by Kyocera, and featuring modern Zeiss optics...
and the medium-format HasselbladHasselbladVictor Hasselblad AB is a Swedish manufacturer of medium-format cameras and photographic equipment based in Gothenburg, Sweden.The company is best known for the medium-format cameras it has produced since World War II....
cameras. The design was physically large, being two focal lengths in length and one focal length in diameter. There are two menisci at the front, and a single strong meniscus element at the rear. The rear element is close to the film plane for low distortion and better contrast, but interferes with the mirror on a single-lens reflex camera. - The Goerz Dagor has two symmetrical cemented triplets (6 elements in 2 groups). The two outer elements are positive, one of the inner elements is used to correct spherical aberration, and the other to flatten the field. There are only 4 glass-to-air interfaces, giving better flare and contrast than lenses with more elements, particularly important before the introduction of coated lenses. Reputed to have good sharpness and a large image circle, although there is softness at the edges.
File:Hypergon.png|Hypergon
File:Topogon.png|Topogon
File:Hologon.png|Hologon
File:Biogon21.png|Biogon
File:Dagor.png|Dagor
Normal lens designs
- Anastigmat is an achromatic lensAchromatic lensAn achromatic lens or achromat is a lens that is designed to limit the effects of chromatic and spherical aberration. Achromatic lenses are corrected to bring two wavelengths into focus in the same plane....
used to reduce or eliminate astigmatismAstigmatismAn optical system with astigmatism is one where rays that propagate in two perpendicular planes have different foci. If an optical system with astigmatism is used to form an image of a cross, the vertical and horizontal lines will be in sharp focus at two different distances...
designed specifically for photographic applications. All modern lenses are anastigmatic; lenses produced in the early days when this was a new feature often had the word Anastigmat in their name: Voigtländer Anastigmat Skopar.
- A TessarTessarThe Tessar is a famous photographic lens design conceived by physicist Paul Rudolph in 1902 while he worked at the Zeiss optical company and patented by Zeiss; the lens type is usually known as the Zeiss Tessar....
comprises four elements in three groups, one positive crown glassCrown glassCrown glass is either of two kinds of glass:*Crown glass was a type of hand-blown window glass.*Crown glass is a type of optical glass used in lenses....
element on the front, one negative flint glassFlint glassFlint glass is optical glass that has relatively high refractive index and low Abbe number. Flint glasses are arbitrarily defined as having an Abbe number of 50 to 55 or less. The currently known flint glasses have refractive indices ranging between 1.45 and 2.00...
element at the center and a negative plano-concave flint glass element cemented with a positive convex crown glass element at the rear. Many manufacturers have produced lenses of this type under their own names.
The Tessar design is suitable for front-element focussing, but unit focussing is used on large format cameras.
- The Heliar design consists of 5 elements in three groups with cemented doublets, allowing correction of spherical, chromatic, and astigmatic aberrations.
- A PlanarZeiss PlanarThe Zeiss Planar is a photographic lens designed by Paul Rudolph at Carl Zeiss in 1896. Rudolph's original was a six-element symmetrical design....
design is one with 4 groups of 6 elements, and a flat field design. Its symmetrical optical configuration produces low spherical aberration and astigmatism. The design was not widely used until coating processes were available, due to the very low contrast caused by light loss from the large number of transmission surfaces. - The SonnarZeiss SonnarThe Sonnar is a photographic lens originally designed by Dr. Ludwig Bertele in 1924 and patented by Zeiss Ikon. It was notable for its relatively light weight, simple design and fast aperture. The name "Sonnar" is derived from the German word "Sonne", meaning sun...
design originally had six elements, later seven, in three groups. The design uses fewer elements than the Planar design and is smaller and less expensive. It has more aberrations but better contrast and less flare than the Planar, a larger maximum aperture and lower chromatic aberration than the Tessar. Large format Sonnars have good sharpness and contrast at large apertures, but are large and heavy, and coverage does not allow much use of movements. The Sonnar has good edge contrastContrast (vision)Contrast is the difference in visual properties that makes an object distinguishable from other objects and the background. In visual perception of the real world, contrast is determined by the difference in the color and brightness of the object and other objects within the same field of view...
at all apertures, but some softness at wide apertures. - The Artar is a true apochromatic 4-element in 4 groups symmetrical process lens for the graphic arts, very well corrected for other aberrations. It was designed by Walter Zschokke of Goerz in 1904, based on Emile Von Hoegh's dialytehttp://www.panix.com/~zone/photo/czlens.htm. If uncoated it is subject to flare due to the 8 air-to-glass surfaces.
Large format lenses are photograph
Photograph
A photograph is an image created by light falling on a light-sensitive surface, usually photographic film or an electronic imager such as a CCD or a CMOS chip. Most photographs are created using a camera, which uses a lens to focus the scene's visible wavelengths of light into a reproduction of...
ic optic
Optic
Optic may mean:* optic, a British term for a device for dispensing fixed amounts of alcoholic spirits* Optics, the study of the behavior and properties of light* An optical element or component, such as a lens, prism, or mirror...
s that provide an image circle
Image circle
The image circle, or circle of illumination, of a lens is the circular area in the image plane formed by the cone of light transmitted by the lens . Within this circle is the smaller circle for which image definition is acceptable, the circle of good definition ; however, some authors make no...
large enough to cover large format film
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...
or plates
Photographic plate
Photographic plates preceded photographic film as a means of photography. A light-sensitive emulsion of silver salts was applied to a glass plate. This form of photographic material largely faded from the consumer market in the early years of the 20th century, as more convenient and less fragile...
. Large format lenses are typically used in large format
Large format
Large format refers to any imaging format of 4×5 inches or larger. Large format is larger than "medium format", the 6×6 cm or 6×9 cm size of Hasselblad, Rollei, Kowa, Pentax etc cameras , and much larger than the 24×36 mm frame of 35 mm format.The main advantage...
cameras and view camera
View camera
The view camera is a type of camera first developed in the era of the Daguerreotype and still in use today, though with many refinements. It comprises a flexible bellows which forms a light-tight seal between two adjustable standards, one of which holds a lens, and the other a viewfinder or a...
s.
Photographic optics generally project a circular image behind the lens
Lens (optics)
A lens is an optical device with perfect or approximate axial symmetry which transmits and refracts light, converging or diverging the beam. A simple lens consists of a single optical element...
. On smaller format cameras the image circle generally covers only the intended film size with little room to spare. Large format lenses are an exception. For large format use the circular patch of image light usually extends beyond the minimum size circle needed to fully cover the rectangle of the film. The extra image offers some or a great deal of room to spare since large format cameras usually make use of camera movements that re-align the lens away from dead center on the film. The film is often positioned as far off center as just inside the periphery of the image circle.
Lens designs
Lenses of the same general construction are often given a name implying this design. For example, a Tessar always has four elements in three groups as described below, although Tessars have been produced with different focal lengths and maximum apertures for many decades. Sometimes a name does not identify a specific design; Kodak's Ektar lens brand name encompasses many different types. Sometimes different manufacturers use different names for lenses of the same type; for example the Voigtländer Skopar is of Tessar design. And sometimes identical lenses are sold under different names and at different prices; for example, lenses branded as Rodenstock and Caltar.Early lenses suffered from flare and low contrast, worsening as the number of lens-air interfaces increased. The introduction of and improvements in anti-reflective coating
Anti-reflective coating
An antireflective or anti-reflection coating is a type of optical coating applied to the surface of lenses and other optical devices to reduce reflection. This improves the efficiency of the system since less light is lost. In complex systems such as a telescope, the reduction in reflections also...
s vastly reduced flare; some many-element lens designs which had been abandoned due to low contrast in spite of otherwise excellent performance became practical.
Lenses designed for use with monochromatic film, first orthochromatic
Orthochromatic
- Orthochromatic photography :Orthochromatic photography refers to a photographic emulsion that is sensitive to only blue and green light, and thus can be processed with a red safelight. The increased blue sensitivity causes blue objects to appear lighter and red ones darker...
, then panchromatic
Panchromatic
Panchromatic film is a type of black-and-white photographic film that is sensitive to all wavelengths of visible light. A panchromatic film therefore produces a realistic reproduction of a scene as it appears to the human eye. Almost all modern photographic film is panchromatic, but some types are...
, had less exacting requirements regarding chromatic aberrations than when colour film is used. When using older lenses today one should check that chromatic aberrations and flare are acceptable for the application.
Wide-angle lens designs
- The Hypergon is a wide angle lens that covers a flat field. It is constructed symmetrically consisting of two deep meniscusMeniscusThe meniscus is the curve in the upper surface of a liquid close to the surface of the container or another object, caused by surface tension. It can be either convex or concave. A convex meniscus occurs when the molecules have a stronger attraction to each other than to the material of the...
elements that almost form a sphereSphereA sphere is a perfectly round geometrical object in three-dimensional space, such as the shape of a round ball. Like a circle in two dimensions, a perfect sphere is completely symmetrical around its center, with all points on the surface lying the same distance r from the center point...
. The apertureApertureIn 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,...
is limited to f/20 due to sphericalSpherical aberrationthumb|right|Spherical aberration. A perfect lens focuses all incoming rays to a point on the [[Optical axis|optic axis]]. A real lens with spherical surfaces suffers from spherical aberration: it focuses rays more tightly if they enter it far from the optic axis than if they enter closer to the...
and chromatic aberrationChromatic aberrationIn optics, chromatic aberration is a type of distortion in which there is a failure of a lens to focus all colors to the same convergence point. It occurs because lenses have a different refractive index for different wavelengths of light...
s. - The Topogon is a double Gauss design arranged in a symmetrical design. Due to its wide angle coverage, and the small distortion, it and the MetrogonMetrogonMetrogon is a high resolution, low-distortion, extra-wide field photographic lens design, popularized by Bausch and Lomb. Variations of this design are said to have been used extensively by the US military for use in aerial photography on the T-11 camera .The most common Metrogon lenses have a f...
became the standard aerial lens until it was displaced in 1952. - The Hologon is a modification of the Biogon lens design. It contains a rear element that is close to film planeFilm planeA film plane is the area inside any image taking device with a lens and a digital sensor or film; such as a camera. The film plane varies in distance from the lens focal point in each manufacturer...
for better contrast, but interferes with mirror for SLRSingle-lens reflex cameraA single-lens reflex camera is a camera that typically uses a semi-automatic moving mirror system that permits the photographer to see exactly what will be captured by the film or digital imaging system, as opposed to pre-SLR cameras where the view through the viewfinder could be significantly...
. There is significant light falloff at edges, so it is frequently used with ND center graduated filters. - The Biogon is an ultra-wide-angle design by Ludwig BerteleLudwig BerteleLudwig Jakob Bertele was a German optics constructor. His developments received universal recognition and serve as a basis for considerable part of optical designs, which are used in modern world.-Biography:...
based on a double-ended reversed-telephoto objective. It was made by Zeiss for their 35mm ContaxContaxContax was a camera brand noted for its unique technical innovation and a wide range of Zeiss lenses, noted for their high optical quality. Its final incarnation was a line of 35 mm, medium format and digital cameras engineered and manufactured by Kyocera, and featuring modern Zeiss optics...
and the medium-format HasselbladHasselbladVictor Hasselblad AB is a Swedish manufacturer of medium-format cameras and photographic equipment based in Gothenburg, Sweden.The company is best known for the medium-format cameras it has produced since World War II....
cameras. The design was physically large, being two focal lengths in length and one focal length in diameter. There are two menisci at the front, and a single strong meniscus element at the rear. The rear element is close to the film plane for low distortion and better contrast, but interferes with the mirror on a single-lens reflex camera. - The Goerz Dagor has two symmetrical cemented triplets (6 elements in 2 groups). The two outer elements are positive, one of the inner elements is used to correct spherical aberration, and the other to flatten the field. There are only 4 glass-to-air interfaces, giving better flare and contrast than lenses with more elements, particularly important before the introduction of coated lenses. Reputed to have good sharpness and a large image circle, although there is softness at the edges.
File:Hypergon.png|Hypergon
File:Topogon.png|Topogon
File:Hologon.png|Hologon
File:Biogon21.png|Biogon
File:Dagor.png|Dagor
Normal lens designs
- Anastigmat is an achromatic lensAchromatic lensAn achromatic lens or achromat is a lens that is designed to limit the effects of chromatic and spherical aberration. Achromatic lenses are corrected to bring two wavelengths into focus in the same plane....
used to reduce or eliminate astigmatismAstigmatismAn optical system with astigmatism is one where rays that propagate in two perpendicular planes have different foci. If an optical system with astigmatism is used to form an image of a cross, the vertical and horizontal lines will be in sharp focus at two different distances...
designed specifically for photographic applications. All modern lenses are anastigmatic; lenses produced in the early days when this was a new feature often had the word Anastigmat in their name: Voigtländer Anastigmat Skopar.
- A TessarTessarThe Tessar is a famous photographic lens design conceived by physicist Paul Rudolph in 1902 while he worked at the Zeiss optical company and patented by Zeiss; the lens type is usually known as the Zeiss Tessar....
comprises four elements in three groups, one positive crown glassCrown glassCrown glass is either of two kinds of glass:*Crown glass was a type of hand-blown window glass.*Crown glass is a type of optical glass used in lenses....
element on the front, one negative flint glassFlint glassFlint glass is optical glass that has relatively high refractive index and low Abbe number. Flint glasses are arbitrarily defined as having an Abbe number of 50 to 55 or less. The currently known flint glasses have refractive indices ranging between 1.45 and 2.00...
element at the center and a negative plano-concave flint glass element cemented with a positive convex crown glass element at the rear. Many manufacturers have produced lenses of this type under their own names.
The Tessar design is suitable for front-element focussing, but unit focussing is used on large format cameras.
- The Heliar design consists of 5 elements in three groups with cemented doublets, allowing correction of spherical, chromatic, and astigmatic aberrations.
- A PlanarZeiss PlanarThe Zeiss Planar is a photographic lens designed by Paul Rudolph at Carl Zeiss in 1896. Rudolph's original was a six-element symmetrical design....
design is one with 4 groups of 6 elements, and a flat field design. Its symmetrical optical configuration produces low spherical aberration and astigmatism. The design was not widely used until coating processes were available, due to the very low contrast caused by light loss from the large number of transmission surfaces. - The SonnarZeiss SonnarThe Sonnar is a photographic lens originally designed by Dr. Ludwig Bertele in 1924 and patented by Zeiss Ikon. It was notable for its relatively light weight, simple design and fast aperture. The name "Sonnar" is derived from the German word "Sonne", meaning sun...
design originally had six elements, later seven, in three groups. The design uses fewer elements than the Planar design and is smaller and less expensive. It has more aberrations but better contrast and less flare than the Planar, a larger maximum aperture and lower chromatic aberration than the Tessar. Large format Sonnars have good sharpness and contrast at large apertures, but are large and heavy, and coverage does not allow much use of movements. The Sonnar has good edge contrastContrast (vision)Contrast is the difference in visual properties that makes an object distinguishable from other objects and the background. In visual perception of the real world, contrast is determined by the difference in the color and brightness of the object and other objects within the same field of view...
at all apertures, but some softness at wide apertures. - The Artar is a true apochromatic 4-element in 4 groups symmetrical process lens for the graphic arts, very well corrected for other aberrations. It was designed by Walter Zschokke of Goerz in 1904, based on Emile Von Hoegh's dialytehttp://www.panix.com/~zone/photo/czlens.htm. If uncoated it is subject to flare due to the 8 air-to-glass surfaces.
Image:Tessar.png|Tessar
Image:Heliar.png|Heliar
Image:Planar 1896.png|Planar
Image:Sonnar.png|Sonnar
Image:Artar.png|Artar
Telephoto lens designs
A true telephoto lensTelephoto lens
In photography and cinematography, a telephoto lens 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 group that extends the light path to create a long-focus...
is designed to require less bellows
Bellows
A bellows is a device for delivering pressurized air in a controlled quantity to a controlled location.Basically, a bellows is a deformable container which has an outlet nozzle. When the volume of the bellows is decreased, the air escapes through the outlet...
extension than a long-focus lens of the same focal length.
Image:Sonnartele135.png|Sonnar telephoto lens.