Double-Gauss
Encyclopedia
Design
The double Gauss lens consists of two back-to-back Gauss lensGauss lens
The Gauss lens consists of two lenses; in its most basic form, a positive meniscus lens on the object side and a negative meniscus lens on the image side. The power of the positive element predominates, but the negative element corrects for chromatic aberration....
es (a design with a positive meniscus lens on the object side and a negative meniscus lens on the image side) making two positive meniscus lenses on the outside with two negative meniscus lenses inside them. The symmetry of the system and the splitting of the optical power into many elements reduces the optical aberrations within the system. There are many variations of the design. Sometimes extra lens elements are added. The basic lens type is one of the most developed and utilized photographic lenses. The design forms the basis for many camera lenses in use today, especially the wide-aperture standard lenses used on 35 mm and other small-format cameras. It can offer good results up to with a wide field of view
Field of view
The field of view is the extent of the observable world that is seen at any given moment....
, and has sometimes been made at 1.0. Extra wide aperture f/1.4 Double Gauss lenses usually have seven elements for extra aberration control. Modern super wide aperture models can have eight or more elements. Moderate aperture f/2.8 versions can be simplified to five elements.
The Double Gauss was likely the most intensively studied lens formula of the twentieth century, producing dozens of major variants, scores of minor variants, hundreds of marketed lenses and tens of millions of unit sales. It had almost no flaws, except for a bit of oblique spherical aberration, which could lower peripheral contrast. Double Gauss/Planar tweaks were the standard wide aperture, normal and near normal prime lens for sixty years.
History
The original two element Gauss was a telescope objective lensObjective (optics)
In an optical instrument, the objective is the optical element that gathers light from the object being observed and focuses the light rays to produce a real image. Objectives can be single lenses or mirrors, or combinations of several optical elements. They are used in microscopes, telescopes,...
consisting of closely spaced positive and negative menisci, invented in 1817 Carl Friedrich Gauss
Carl Friedrich Gauss
Johann Carl Friedrich Gauss was a German mathematician and scientist who contributed significantly to many fields, including number theory, statistics, analysis, differential geometry, geodesy, geophysics, electrostatics, astronomy and optics.Sometimes referred to as the Princeps mathematicorum...
as an improvement to the Fraunhofer
Joseph von Fraunhofer
Joseph von Fraunhofer was a German optician. He is known for the discovery of the dark absorption lines known as Fraunhofer lines in the Sun's spectrum, and for making excellent optical glass and achromatic telescope objectives.-Biography:Fraunhofer was born in Straubing, Bavaria...
telescope objective by adding a meniscus lens to its single convex and concave lens design. Alvan Clark
Alvan Clark
Alvan Clark , born in Ashfield, Massachusetts, the descendant of a Cape Cod whaling family of English ancestry, was an American astronomer and telescope maker. He was a portrait painter and engraver , and at the age of 40 became involved in telescope making...
and Bausch & Lomb further refined the design in 1888 by taking two of these lenses and placing them back to back making a "double Gauss" with indifferent photographic results. Current double Gauss lenses can be traced back to an 1895 improved design, when Paul Rudolph
Paul Rudolph (physicist)
Paul Rudolph was a German physicist who designed the first anastigmatic lens while working for Carl Zeiss. After World War I, he joined the Hugo Meyer optical company, where he designed most of their cine lenses. -Work:...
of Carl Zeiss Jena thickened the interior negative menisci and converted to them to cemented doublets of two elements of equal refraction but differing dispersion in the Zeiss Planar
Zeiss Planar
The Zeiss Planar is a photographic lens designed by Paul Rudolph at Carl Zeiss in 1896. Rudolph's original was a six-element symmetrical design....
of 1896 to correct for chromatic aberration
Chromatic aberration
In 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...
. It was the original six element symmetric f/4.5 Double Gauss lens. Horace Lee added a slight asymmetry to the Planar in 1920, and created the Taylor, Taylor & Hobson Series 0 (also called the Lee Opic, UK) f/2 lens. It was commercially unsuccessful, but its asymmetry is the foundation of the modern Double Gauss, including the Zeiss Biotar. Later the design was developed with additional glasses to give high-performance lenses of wide aperture. The main development was due to Taylor Hobson
Cooke Optics
Cooke Optics Ltd. is a camera lens manufacturing company based in Leicester, known earlier as Taylor, Taylor and Hobson and then Taylor Hobson. T. S. Taylor, an optician, his brother W. Taylor, an engineer, and a Mr Hobson, a businessman, formed the company in 1886.The name Cooke originally came...
in the 1920s, resulting in the f/2.0 Opic and later the Speed Panchro designs, which were licensed to various other manufacturers.
The Zeiss Biotar 58mm f/2 (Germany) appeared on the Ihagee Kine Exakta (1936, Germany), the first widely available 35mm
135 film
The term 135 was introduced by Kodak in 1934 as a designation for cartridge film wide, specifically for still photography. It quickly grew in popularity, surpassing 120 film by the late 1960s to become the most popular photographic film format...
single-lens reflex camera
Single-lens reflex camera
A 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...
s, in 1939. It was also the standard lens on the VEB Zeiss Ikon (Dresden) Contax S (1949, East Germany), the first pentaprism eyelevel viewing 35mm SLR. The Biotar, originally designed in 1927, had a six element asymmetric Double Gauss formula. Post-World War II Zeiss (Oberkochen, West Germany) no longer uses the Biotar name; instead lumping any Double Gauss variant under the Planar name.
Several contemporaneous competing, but less famous lenses, were similar to the Biotar, such as Albrecht Tronnier's Schneider Xenon (1925, Germany). For example, three asymmetric Double Gauss lenses were produced in 1934 for Ihagee VP Exakta (1933, Germany) the type 127 roll film
127 film
127 is a film format for still photography. The image format is usually a square 4×4 cm, but rectangular 4×3 cm and 4×6 cm are also standard. Oddly, C. F. Foth & Co. used 36×24 mm for its first “Derby” model....
SLR
Single-lens reflex camera
A 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...
camera: 8 cm f/2 versions of both the Biotar and Xenon, as well as the Dallmeyer Super Six 3 inch f/1.9 (UK).
Early Double Gauss permutations for 35mm cameras included the Kodak Ektar 45mm f/2 on the Kodak Bantam Special (1936, USA), the Kodak Ektar 50mm f/1.9 for the Kodak Ektra (1941, USA), the Voigtländer Ultron 50mm f/2 on the Voigtländer Vitessa (1951, West Germany) and the Leitz Summicron 50mm f/2 for the Leica M3 (1953, West Germany).
During the 1960s and 70s, every optical house had Double Gauss normal lenses jockeying for sales. For example, compare the Tokyo Optical RE Auto-Topcor 5.8 cm f/1.4 for the Topcon RE Super/Super D (1963), Olympus G. Zuiko Auto-S 40mm f/1.4 for the Olympus Pen F (lens 1964, camera 1963), Yashica Auto Yashinon DX 50mm f/1.4 for the Yashica TL Super (1967), Canon FL 50mm f/1.4 (v2) for the Canon FT (lens 1968, camera 1966), Asahi Optical Super Takumar 50mm f/1.4(v2) for the Pentax Spotmatic (lens 1968, camera 1964), Fuji Fujinon 50mm f/1.4 for the Fujica ST701 (1971), Minolta MC Rokkor-PG 50mm f/1.4 for the Minolta XK/XM/X-1 (1973), Zeiss Planar HFT 50mm f/1.4 for the Rolleiflex SL350 (1974), Konishiroku Hexanon AR 50mm f/1.4 for the Konica Autoreflex T3 (lens 1974, camera 1973) and Nippon Kokagu Nikkor (K) 50mm f/1.4 (New) for the Nikon F2 (lens 1976, camera 1971); all from Japan except Zeiss, West Germany.
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 dominated the 1980s and 90s, and so, there were few new Double Gauss normal lenses. Zooms continue to dominate the digital era, but many new prestige low production Double Gauss lenses have appeared. Compare the Canon EF 50mm f/1.2L USM (2007, Japan), Nikon AF-S Nikkor 50mm f/1.4G (2008, Japan/China), Sigma EX DG HSM 50mm f/1.4 (2008, Japan), (Cosina) Voigtländer Nokton 50mm f/1.1 (2009, Japan) or Leica Noctilux-M 50mm f/0.95 ASPH (2009, Germany) with their antecedents.
The design is presently used in inexpensive-but-high-quality fast lenses such as the Canon EF 50mm 1.8
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...
and Nikon 50 mm 1.8D AF Nikkor
Nikon 50 mm f/1.8D AF Nikkor
The Nikon 50 mm 1.8D AF Nikkor is one of Nikon's 50 mm lenses. This Double-Gauss lens replaces the 50mm 1.8 . A 50 mm prime lens is the normal lens for the 135 film format...
. It is also used as the basis for faster designs, with elements added, such as a seventh element as in both Canon and Nikon's 50 mm 1.4 offerings or an aspherical seventh element in Canon's 50 mm 1.2. The design appears in other applications where a simple fast 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...
is required (~53° diagonal) such as in projectors.