Lens

Basic

• Frame size and crop factor : small-format (the modern name is "full-frame camera", "Full frame"), half-format - modern varieties are called - "APS cameras", medium format , large format with a frame size of 9 × 12 cm and large, miniature (large part of common cameras), etc.
• Focal length is the distance from its optical center to the focus through which the focal plane passes, in which lies the plane of the sensor (film), provided that the lens is pointed at infinity. Measured in millimeters;
• Multiplicity of a zoom lens is the ratio of the maximum focal length to the minimum. Often the focal length range is indicated;
• The angular field of the lens is closely related to its focal length and frame size. Sometimes lenses are used on cameras with a smaller frame size than the one for which they were originally designed, and, accordingly, their angular field will be smaller, depending on the sensor of the receiver. For each specific frame size, there is a series that uniquely connects the angular field of the lens with its focal length;
• Aperture ;
• Maximum relative aperture (sometimes incorrectly called aperture );
• The level and nature of optical distortions ( aberrations );
• Resolution ;
• Type of bayonet mount or thread diameter for attaching to the camera - for interchangeable photographic or filming lenses;
• Anamorphosis coefficient (anamorphoses) - for anamorphic lenses;

Complementary and Clarifying

• Working distance or working distance - for interchangeable lenses. The distance between the reference plane of the mounting frame and the focal plane of the lens. In most cases, it is determined by the type of bayonet mount , it is important for threaded types of mounts (for example, lenses with an M39 × 1 mount thread were also manufactured for a working length of 28.8 mm for the Leica , FED , Zorkiy cameras, and under 45.2 mm working segment for Zenith SLR cameras).
• Minimum relative aperture (maximum number of aperture, for example, 16 or 22) - is determined by the design features of the diaphragm.
• The minimum focusing distance (MDF), or the maximum macro scale for macro lenses (for example, 55 mm, 1: 1) - is determined by the focal length and frame design .
• Diameter and thread pitch for attaching light filters .
• Charts MTF (Modulation Transfer Function - Refines Resolution ).
• Optical design of the lens. A larger number of lenses allows designers to calculate a lens with better corrected aberrations, but it reduces light transmission and increases the risk of spurious reflections that reduce image contrast. In addition, a greater number of surfaces that need to be polished increases the cost of production and toughens the requirements for the accuracy of manufacture of each part. That is why simple optical schemes such as Tessar are still successfully applied and will be applied.
• The presence of aspherical lenses .
• The presence of lenses from special grades of glass (low dispersion, with a high refractive index).
• Type of enlightenment .
• Design and features of the frame and mount . For example, a “Pump-action” frame (from similarities with a pump-action shotgun ) - changing the focal length and focusing is carried out by one ring, the axial movement of which changes the focal length, and turning makes focusing. More traditional is the presence of two different controls.

• A regular lens is the main (most commonly used) lens of a particular photographer on a particular camera. Often called a normal any normal lens .
• Kit lens (from the English. Kit - kit) - slang word - interchangeable lens that comes with the camera for sale. Often, a specific entry-level zoom lens comes with budget cameras ( EF-S 18-55mm f / 3.5-5.6 for Canon, AF-S DX NIKKOR 18-55 mm f / 3.5-5.6 VA for Nikon, 18-55 mm f / 3.5-5.6 Sony, DA 18-55 mm f / 3.5-5.6 AL with Pentax, etc.)
• standard - quite often used in completely different senses: regular , normal , complete (whale).

Types of lenses by design (optical design)

Creating distortion-free lenses has long been an art rather than a science. Particularly successful lens layouts have remained in the history of technology under their own names:

• Monocle - the simplest lens, consisting of a single collecting lens .
• Periscope - a symmetrical lens, consisting of two collective lenses.
• Triplet - the simplest version of the anastigmata , consisting of three non-glued lenses, two collecting and one scattering between them.
• A retro-focus lens is a class of lenses, characterized in that the distance from the rear optical surface to the focal plane is greater than the focal length, which allows you to design a short-focus lens with an elongated rear segment . Gained popularity in connection with the proliferation of single-lens reflex cameras .
• A telephoto lens is a class of telephoto lenses in which the distance from the front optical surface to the rear focal plane is less than the focal length.

• A mirror-lens lens is a class of lenses that, in addition to lenses , contain mirrors . As a rule, long-focus and ultra-long-focus lenses are made according to this scheme to reduce their overall dimensions. The fastest lenses are another area of ​​catadioptric lenses. Declared a mirror-lens lens with multiple light reflection "Origami" for ultra-compact equipment ^[3] .
• The mirror lens contains only mirrors in the design. Mirrors do not have dispersion ; therefore, such optical schemes are found in astronomy, and in many technical fields, for example, in nanolithography ^[4] .

By the type of optical ( aberration ) correction used

• Achromat is a lens with corrected chromatic aberration. Achromat chromatism is corrected for the rays of two wavelengths, the rays of the other colors converge near the main focus, and form the so-called. secondary spectrum, or high-order chromatism.
• Aplanat is a lens with corrected spherical, chromatic, and coma aberration. Initially, it was called a lens with such properties, consisting of two symmetrical achromatic lenses .
• Anastigmatism is a lens in which, in addition to aplanatic correction, astigmatism and field curvature are additionally corrected. In anastigmata, to one degree or another, all six basic aberrations are corrected. Almost all modern photographic, filming and television lenses are anastigmata.
• Apochromat is a lens whose chromatic aberration is better corrected than achromat. In contrast, in apochromat, the chromaticity of the position is corrected for rays of three wavelengths, i.e. image quality improves significantly, especially for telephoto lenses (green and purple borders are reduced).
• Semi-apochromate is an achromat, the chromatism of which is corrected for rays of two wavelengths, but the secondary spectrum is greatly reduced in comparison with ordinary achromat.
• Superechromate (Superchromat) is an objective in which chromatism is corrected for rays of four wavelengths.

The following terms are also used for microscope lenses:

• Planachromat -
• Planochrome -
• Stigmachromats -
• Microfluores are lenses in which aberrations for one of the three wavelengths are corrected within 0.25${\displaystyle \mathrm{<span><span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">\lambda </span></span></span>}}$ {\ displaystyle \ lambda}   .

By the range of focal lengths

• Fix - any lens with a fixed focal length, a slang word, an abbreviation used to contrast zoom lenses . In cinematic usage, such lenses are called discrete .
• Varifocal lens , Zoom (Eng. Varifocal lens, zoom) - a lens with a variable focal length ( zoom (Eng. Parfocal lens)).

By focus method

• Autofocus - a lens equipped with an autofocus actuator and an appropriate interface for connecting to the camera.
• Manual - a lens that requires manual focusing with an appropriate mechanism.
• Fix focus is a lens focused on a specific distance (most often on hyperfocal distance or “infinity”) and fixed in this position ^[5] .

By angular field (focal length)

Classification of photographic lenses is widely used according to the angular field , by equivalent focal length (the value that the lens will have if, while maintaining its angle of view, its matrix is ​​scaled to a frame size of 24 × 36 mm), or by focal length referred to frame sizes. This characteristic largely determines the scope of the lens:

• A normal lens is a lens whose focal length is approximately equal to the diagonal of the frame. A normal lens occupies a position between a wide-angle and a portrait lens. For a 35 mm film, the frame diagonal is 43 mm, and a lens with a focal length of 35–70 mm is considered normal, while the most popular value, which later became the standard, is 50 mm. The angular field of a normal lens lies in the range from 45 ° to 60 ° ^[6] . It is believed that the perception of the perspective of a picture taken by a normal lens is closest to the normal perception of the perspective of the surrounding world by a person. ^{[7] [8]}
• “Fisheye”, “Fish” - a lens with an angular field of 180 ° or more. It is characterized by its inherent strongly pronounced distortion , without which it is impossible to realize such viewing angles. Distinguish between “circular fisheries” - with the image in the form of a circle, a diameter equal to the height of the frame, or less, and “diagonal fishes” - with the usual full-frame image, and a field of view along the diagonal of 180 °.
• An ultra-wide-angle lens is a lens whose angular field is 83 ° or more, and the focal length is less than the small side of the frame. Ultra-wide-angle lenses have an exaggerated transmission of perspective and are often used to give the image additional expressiveness.
• A wide-angle lens (syn. Short-focus lens) is a lens with an angular field from 63 ° to 82 ° inclusive, the focal length of which is less than the wide side of the frame. Often used for shooting in confined spaces, such as interiors.
• A portrait lens is a lens whose focal length is intermediate between normal and telephoto. Standard specifications - 85 mm with aperture of 1 / 2.0 (varies from 1 / 2,8 to 1 / 1,2). With a smaller focal length, lenses give angle distortions that change the proportions of the face. At the same time, with an increase in the focal length, in addition to a favorable reduction in angle distortion, it becomes possible, for good background blurring, to cost a smaller aperture of the lens, so the border between the portrait and telephoto lens is arbitrary. Usually, a range of 2–4 diagonal frames is meant, that is, a lens with a focal length of 85–150 mm and an angular field of 16 ° –28 °. For a portrait lens, in addition to technical parameters, the nature of the optical pattern and bokeh are important.
• Telephoto lens (telefoto) - a lens in which the focal length exceeds the frame diagonal by 2-3 times and up to seven times. It has an angular field from 10 ° to 39 ° (focal lengths of 85-300 mm), and is intended for shooting distant objects.
• Super-long focus lens (supertelefoto) - a lens with an angular field of less than 9 ° (focal lengths of more than 300 mm).

Currently, a type of zoom lens has been widely used, called a zoom lens ( zoom , “zoom”).

According to the purpose (shooting lenses)

The purpose of the lens is essential. Before you start shooting, the question always arises of what to shoot.

• Portrait Lens - Used to take portraits . It should give a soft image without geometric distortion. Telephoto lenses or lenses with a fixed focal length in the range of 80-200 mm (for a film of 35 mm) are often used as portrait ones. Classic are 85 mm and 130 mm. The specialized portrait lens is designed so that it shows the minimum aberration when focusing from a few meters, that is, when shooting a portrait, to the detriment of the image quality “at infinity”. Almost mandatory for a portrait lens is a large (better than 2.8) relative aperture, and the nature of the boke is very important;
• A macro lens is a lens specially adjusted for shooting from short distances comparable to its focal length. As a rule, it is used for macro photography of small objects close-up, up to a scale of 1: 1. Allows you to shoot with high contrast and sharpness. They have a lower aperture ratio than other types of lenses similar in focal length. Typical focal lengths are from 50 to 180 mm. In addition, it usually has a special frame, allowing a large extension ^[9] ;
• Telephoto lens - usually used for shooting distant objects. Длиннофокусный объектив, в котором расстояние от передней оптической поверхности до задней фокальной плоскости меньше фокусного расстояния, именуется телеобъектив ;
• Репродукционный объектив — используется при пересъёмке чертежей, технической документации и т. д. Должен обладать минимальными геометрическими искажениями, минимальным виньетированием и минимальной кривизной поля изображения ;
• Шифт-объектив (объектив со сдвигом, от англ. shift ) — используется для архитектурной и иной технической съёмки и позволяет предотвратить искажение перспективы .
• Тилт-объектив (разновидность шифт-объектива с функцией наклона, от англ. tilt ) — используется для получения резкого изображения неперпендикулярных оптической оси объектива протяжённых объектов при макросъёмке, а также для получения художественных эффектов. ^[10] .
• Тилт-шифт объектив — класс объективов, сочетающий в себе сдвиг и наклон оптической оси. Позволяет использовать возможности карданных камер в малоформатной фотографии. Крупнейшие производители фототехники имеют в линейке оптики хотя бы один такой объектив, например, Canon TS-E 17 F4L .
• Стеноп (пинхол) (объектив камеры-обскуры , небольшое отверстие, от англ. pinhole ) — используется для съёмок пейзажей или иных объектов с очень большими выдержками и с получением в одном кадре одинаково резкого изображения от макрорасстояний до бесконечности;
• Софт-объектив (мягкорисующий объектив, от англ. soft ) — объектив с недоисправленными аберрациями, обычно сферической, или с вносящими искажения элементами конструкции. Служит для получения эффекта размытости, дымки и т. п. при сохранении резкости. ^[11] Применяются в портретной съёмке. Немногим близкий эффект дают так называемые «фильтры мягкого фокуса» ^[12] ;
• Суперзум (тревел-зум) ( англ. travel zoom ) — универсальный вариообъектив относительно малого веса и максимального диапазона фокусных расстояний. Используется при пониженных требованиях к качеству снимка и повышенных — к оперативности использования и массе.
• Ультразум — суперзум, который отличается повышенными кратностью диапазона фокусных расстояний, обычно начиная с пяти.
• Гиперзум — суперзум, кратность диапазона фокусных расстояний которого обычно больше 15 . Распространены в профессиональных видеокамерах и компактных фотоаппаратах, например, Fujinon A18x7.6BERM ^[13] , Angenieux 60x9,5 ^[14] , Nikon Coolpix P500 (кратность 36), Sony Cyber-shot DSC-HX100V (кратность 30), Canon PowerShot SX30 IS (кратность 35), Nikon Coolpix P90 (кратность 24). Качество изображения объектива, необходимое в видеокамерах, особенно стандартной четкости , позволяет строить объективы с большой кратностью. Кроме того, при малой диагонали матриц видеокамер и компактных фотоаппаратов габариты вариообъектива с большим диапазоном фокусных расстояний несравнимо меньше, чем были бы при таких же параметрах для формата APS-C. Студийные видеокамеры могут оснащаться вариообъективами с кратностью, равной 50 и даже 100 ^[15] .

По передаче пропорций изображения

• Сферические ( аксиально-симметричные ) — объективы, дающие изображение, конгруэнтное объекту съёмки. Такие объективы содержат линзы только с симметричными относительно оптической оси (сферическими или асферическими) преломляющими поверхностями;
• Анаморфотные — киносъёмочные объективы для кинематографических систем с анаморфированием . Такие объективы кроме аксиально-симметричных линз содержат компоненты с цилиндрическими преломляющими поверхностями ^[16] ;

По назначению (прочие объективы)

• Проекционный объектив — используется в проекторах . В отличие от съёмочных объективов, устойчив к значительному нагреву в интенсивном световом потоке. Обладает более простой конструкцией оправы и не оснащен механизмом диафрагмы.
• Объектив микроскопа или микрообъектив — см. Оптический микроскоп#Объективы .
• Telescope lens - has a large size ( aperture value ), to achieve maximum resolution and aperture . There are lens, mirror ( Paraboloid of rotation) and mirror-lens.
• Lens enlarger - frame has a mechanism aiming to sharpen, but has a diaphragm.

Together with the lenses, filters , macrolenses , tele-converters , wide-angle and tele-attachments, other lenses using wrapping rings, reversible rings, raising and lowering rings, extension macro rings , compendiums , ring mounts on the lens body for mounting it on a tripod are used.

The production of lenses is a high-tech field, it requires significant research, sophisticated equipment for processing glass, a complex of scientific and technical research in the field of calculating the shape of lenses, applying antireflection coatings, etc.

Common Lens Brands

Many lenses have their own names assigned to them by the developer.

• Alice
• Wave
• Helios
• Zenitar
• ZM
• Sonnar
• Industar
• Kaleinar
• World
• MTO
• Noctilux
• Ortagoz
• Rodenstock ( Rodenstock GmbH - German manufacturer of high-quality optics, including for large-format cameras and projection optics for enlargers )
• Bearing
• Rubinar
• Russar
• Tair
• Tessar
• Elmarit
• Era
• Jupiter

Lens manufacturers

• Angenieux
• Canon
• Carl Zeiss (one of the oldest legendary manufacturers of high-quality optics)
• Fujinon
• Leica (legendary optics manufacturer)
• Minolta (a manufacturer of optics with a Minolta AF / Minolta MD / MC / SR bayonet mount and others. The photographic division was subsequently absorbed initially by Konica Minolta , and then Sony ).
• Nikkor (trademark of Nikon Corporation )
• Pentax
• Samyang
• Sigma (manufacturer of interchangeable optics for various systems)
• Sony (manufacturer of interchangeable optics with α-mount and E-mount mounts. Α-mount mount is fully compatible with Minolta AF mount)
• Schneider kreuznach
• Takumar
• Tamron (manufacturer of interchangeable optics for various systems)
• Tokina (manufacturer of interchangeable optics for various systems)
• Voigtländer
• Zuiko Digital ( Olympus trademark)
• Zenit - Krasnogorsk Plant them. S. A. Zvereva (OJSC KMZ)
• LZOS - JSC "Lytkarinsky Optical Glass Plant"
• LOMO (lenses of microscopes and telescopes)
• Jupiter (Valdai)

• Lens
• Eyepiece
• Lens kit
• Relative hole
• Lens aberration
• Focal length
• Lens angle
• Lens angular field
• Lens hood
• Optical systems
• Shift lens
• Lens designations
• Lensfun

Classification of lenses by focal length.

• D.S. Volosov . Photographic optics. - 2nd ed. - M .: "Art", 1978. - 543 p. - 10,000 copies.

• I. B. Gordiychuk, V. G. Pell. Directory of cameraman / N. N. Zherdetskaya. - M .: "Art", 1979. - 10,000 copies.

• E.A. Iophis . Photokinotechnics / I. Yu. Shebalin. - M .: "Soviet Encyclopedia", 1981. - S. 215. - 447 p. - 100,000 copies.

• Fomin A.V. § 5. Photographic lenses // General course of photography / T. P. Buldakova. - 3rd. - M.,: "Legprombytizdat", 1987. - S. 12-25. - 256 s. - 50,000 copies.

• Lenses of the Krasnogorsk plant
• Encyclopedia of Pentax lenses and accessories on the site of Bozidar Dimitrov
• Large database of lenses with the ability to compare
• How to choose a lens