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Camera

Camera

:This is the article about the photographing device. For other uses, see CAMERA. rightA camera is a device used to take pictures (usually photographs), either singly or in sequence, with or without sound recording, such as with video cameras. A camera that takes pictures singly is sometimes called a photo camera to distinguish it from a video camera. The name is derived from camera obscura, Latin for "dark chamber", an early mechanism for projecting images in which an entire room functioned much as the internal workings of a modern photographic camera, except there was no way at this time to record the image short of manually tracing it. Cameras may work with the visual spectrum or other portions of the electromagnetic spectrum.

Description

Every camera consists of some kind of enclosed chamber, with an opening or aperture at one end for light to enter, and a recording or viewing surface for capturing the light at the other end. This diameter of the aperture is often controlled by an diaphragm mechanism, but some cameras have a fixed-size aperture. While the size of the aperture and the brightness of the scene control the amount of light that enters the camera during photographing, the shutter controls the length of time that the light hits the recording surface. For example, in lower light situations, the shutter speed should be slower (longer time spent open) to allow the film to capture what little light is present. There are various ways of focusing a camera accurately. The simplest cameras have fixed focus and use a small aperture and wide-angle lens to ensure that everything within a certain range of distance from the lens (usually around 3 metres (10 feet) to infinity) is in reasonable focus. This is usually the kind found on one-use cameras and other cheap cameras. The camera can also have a limited focusing range or scale-focus that is indicated on the camera body. The user will guess or calculate the distance to the subject and adjust the focus accordingly. On some cameras this is indicated by symbols (head-and-shoulders; two people standing upright; one tree; mountains). Rangefinder cameras focus by means of a coupled parallax unit on top of the camera. Single-lens reflex cameras allow the photographer to determine the focus and composition visually using the objective lens and a moving mirror to project the image onto a ground glass or plastic micro-prism screen. Twin-lens reflex cameras use an objective lens and a focusing lens unit (usually identical to the objective lens) in a parallel body for composition and focusing. View cameras use a ground glass screen which is removed and replaced by either a photographic plate or a reusable holder containing sheet film before exposure. Traditional cameras capture light onto photographic film or photographic plate. Video and digital cameras use electronics, usually a charge coupled device (CCD) or sometimes a CMOS sensor to capture images which can be transferred or stored in tape or computer memory inside the camera for later playback or processing. Cameras that capture many images in sequence are known as movie cameras or as ciné cameras in Europe; those designed for single images are still cameras. However these categories overlap, as still cameras are often used to capture moving images in special effects work and modern digital cameras are often able to trivially switch between still and motion recording modes. A video camera is a category of movie camera which stores images onto magnetic tape (either using analogue or digital technology). Stereo camera can take photographs that appear "three-dimensional" by taking two different photographs which are combined to create the illusion of depth in the composite image. Stereo cameras for making 3D prints or slides have two lenses side by side. Stereo cameras for making lenticular prints have 3, 4, 5, or even more lenses. Some film cameras feature date imprinting devices that can print a date on the negative itself.

History

date imprinting date imprinting The first permanent photograph was made in 1826 by Joseph Nicéphore Niépce using a sliding wooden box camera made by Charles and Vincent Chevalier in Paris. However, while this was the birth of photography, the camera itself can be traced back much further. Photographic cameras were a development of the camera obscura, a device dating back at least to the 11th century which uses a pinhole or lens to project an image of the scene outside onto a viewing surface. Before the invention of photography, there was no way to preserve the images produced by these cameras apart from manually tracing them. The first camera that was small and portable enough to be practical for photography was built by Johann Zahn in 1685, though it would be almost 150 years before technology caught up to the point where this was possible. Early photographic cameras were essentially similar to Zahn's model, though usually with the addition of sliding boxes for focusing. Before each exposure a sensitized plate would be inserted in front of the viewing screen to record the image. Jacques Daguerre's popular daguerreotype process utilized copper plates, while the calotype process invented by William Talbot recorded images on paper. The development of the collodion wet plate process by Frederick Scott Archer in 1850 cut exposure times dramatically, but required photographers to prepare and develop their glass plates on the spot, usually in a mobile darkroom. Despite their complexity, the wet-plate ambrotype and tintype processes were in widespread use in the latter half of the 19th century. Wet plate cameras were little different from previous designs, though there were some models (such as the sophisticate Dubroni of 1864) where the sensitizing and developing of the plates could be carried out inside the camera itself rather than in a separate darkroom. Other cameras were fitted with multiple lenses for making making cartes de visite. It was during the wet plate era that the use of bellows for focusing became widespread.

Camera brands

- Agfa
- ARCA-Swiss
- Agilux
- Balda
- Bolex
- Braun
- Bronica
- Burke & James
- Cambo
- Canon
- Casio
- Contax
- Corfield
- Coronet
- Ebony
- FED
- Fujifilm
- Graflex
- Hasselblad
- Hewlett Packard
- Ilford
- Kodak
- Konica
- Leica
- Linhof
- Lomo
- Minolta
- Mamiya
- Minox
- MPP
- Newman & Guardia
- Nikon
- Olympus
- Osaka
- Panasonic
- Pentax
- Polaroid
- Praktica
- Reid
- Ricoh
- Rollei
- Sigma Corporation
- Sony
- Vivitar
- Voigtländer
- Wisner
- Wray
- Yashica
- Zeiss
- Zenit
- Zone VI
- Zorki

External links

- [http://www.camerapedia.org/wiki/Main_Page Camerapedia: a free-content encyclopedia of camera information]
- [http://www.sankey.ws/pinhole.html Pinhole camera for tree photography] Category:Photography Category:Photographic equipment ko:사진기 ja:カメラ

Camera

Description

History

Camera brands

External links

Photographs

:Photo redirects here. For the French magazine, see Photo (magazine). A photograph (often shortened to photo) is an image (or a representation of that on e.g. paper) created by collecting and focusing reflected electromagnetic radiation. The most common photographs are those created of reflected visible wavelengths, producing permanent records of what the human eye can see. Most photographs are made with a camera, which focuses the light onto either photographic film or a CCD or CMOS image sensor. Photographs can also be made by placing objects on photosensitive paper and exposing it to light (the result is often called a photogram) or by placing objects on the platen of a flatbed scanner (see scanner art).

History and special effects

Most traditional photographs are produced with a two-step chemical process. In the two-step process, the film holds a negative image (colours and lights/darks are inverted), which is then transferred onto photographic paper as a positive image. Another widely used film is the positive film used for producing transparencies, usually mounted in cardboard or plastic frames called slides. Slides are widely used by professionals mostly due to their sharpness and accuracy of colour rendition. Most photographs published in magazines are still originally taken on colour transparency film. transparencies Originally almost all photographs were black and white. Although methods for developing color photos were available as early as the late 19th century, they did not become widely available until the 1940s or 50s, and even in until the 1960s most photographs were taken in black and white. Since then, color photography has dominated popular photography, although the black and white format remains popular for amateur photographers and artists. Black and white film is considerably easier to develop than colour. Panoramic format Images can be taken by using special cameras like the Hasselblad Xpan on standard film. Since the 1990s, panoramic photos have been relatively easy for the general population to take on Advanced Photo System film. APS was developed by several of the major film manufacturers to provide a "smart" film with different formats and computerized options available, though APS panoramas were created using a mask in panorama-capable cameras, far less desirable than a true panoramic camera which achieves its effect through wider film format. As with many past ideas in consumer film formats, APS has become less popular and will be discontinued in the near future. Digital photos can be stored in various file formats, of which JPEG is one of the most popular. Many other graphic formats are used, including TIFF, PNG, GIF, and RAW.

Video camera

A video camera can be classified three ways:
- Professional video cameras, such as those used in television production
- Camcorders used by amateurs
- Closed-circuit television used for surveillance

Camera obscura

thumb :For other uses see Camera obscura (disambiguation) The camera obscura (Lat. dark chamber) was an optical device used in drawing, and one of the ancestral threads leading to the invention of photography. Photographic devices today are still known as "cameras". The principle of the camera obscura can be demonstrated with a rudimentary type, just a box (which may be room-size) with a hole in one wall, (see Pinhole cameras for construction details). Light from only one part of a scene will pass through the hole and strike a specific part of the back wall. The projection is made on paper on which an artist can then copy the image. The advantage of this technique is that the perspective is right, thus greatly increasing the realism of the image (correct perspective in drawing can also be achieved by looking through a wire mesh and copying the view onto a canvas with a corresponding grid on it). With this simple do-it-yourself apparatus, the image is always upside-down. By using mirrors, as in the 18th century overhead version illustrated, it is also possible to project a right-side-up image. Another more portable type, as in the second drawing, is a box with an angled mirror projecting onto tracing paper placed on the glass top, the image upright as viewed from the back. As a pinhole is made smaller, the image gets sharper, but the light-sensitivity decreases. With too small a pinhole the sharpness again becomes worse due to diffraction. Practical cameras obscura use a lens rather than a pinhole because it allows a larger aperture, giving a usable brightness while maintaining focus. Some cameras obscura have been built as tourist attractions, often taking the form of a large chamber within a high building that can be darkened so that a 'live' panorama of the world outside is projected onto a horizontal surface through a rotating lens. Although few now survive, examples can be found in Grahamstown in South Africa, Bristol and Portslade village in England, Aberystwyth and Portmeirion in Wales, Kirriemuir, Dumfries and Edinburgh in Scotland, Lisbon in Portugal, and Santa Monica and San Francisco in California, Havana in Cuba, Eger in Hungary, and Cádiz in Spain [http://www.torretavira.com/] The principles of the camera obscura have been known since antiquity. Its potential as a drawing aid may have been familiar to artists by as early as the 15th century; Leonardo da Vinci once described the camera obscura. The Dutch Masters, such as Johannes Vermeer, who were hired as painters in the 17th Century, were known for their magnificent attention to detail. It has been widely speculated that they made use of such a camera, but the extent of their use by artists at this period remains a matter of considerable controversy. 17th Century 17th Century in Ocean Beach (San Francisco)]] Early models were large; comprising either a whole darkened room or a tent (as employed by Johannes Kepler). By the 18th century, following developments by Robert Boyle and Robert Hooke, more easily portable models became available. These were extensively used by amateur artists while on their travels, but they were also employed by professionals, including Paul Sandby, Canaletto and Joshua Reynolds, whose camera (disguised as a book) is now in the Science Museum (London). Such cameras were later adapted by Louis Daguerre and William Fox Talbot for creating the first photographs.

External links

- [http://brightbytes.com/cosite/cohome.html An Appreciation of the Camera Obscura]
- [http://www.pharmaquiz.ch/anime/CameraObscura.htm Flash Animation] - Flash Animation that explains how the Camera Obscura works
- [http://www.giantcamera.com/ The Camera Obscura in San Francisco] - The Giant Camera of San Francisco at Ocean Beach, added to the National Registry of Historic Places in 2001
- [http://www.bbc.co.uk/history/society_culture/art/vermeer_camera_01.shtml Vermeer and the Camera Obscura] by Philip Steadman
- [http://web.onyxnet.co.uk/soc-onyxnet.co.uk/obscuras.htm Sinden Optical Company] - Camera Obscura manufacturer. Category:Optical devices Category:Artistic techniques th:คาเมร่า ออบสคูร่า

Latin

Latin is an ancient Indo-European language originally spoken in the region around Rome called Latium. It gained great importance as the formal language of the Roman Empire. All Romance languages, those being most notably Spanish, French, Portuguese, Italian, and Romanian, are descended from Latin, and many words based on Latin are found in other modern languages such as English. The Latin alphabet, derived from the Greek, remains the most widely-used alphabet in the world. It is said that 80 percent of scholarly English words are derived from Latin (in a large number of cases by way of French). Moreover, in the Western world, Latin was a lingua franca, the learned language for scientific and political affairs, for more than a thousand years, being eventually replaced by French in the 18th century and English in the late 19th. Ecclesiastical Latin remains the formal language of the Roman Catholic Church to this day, and thus the official national language of the Vatican. The Church used Latin as its primary liturgical language until the Second Vatican Council in the 1960s. Latin is also still used (drawing heavily on Greek roots) to furnish the names used in the scientific classification of living things. The modern study of Latin, along with Greek, is known as Classics.

Main features

Latin is a synthetic inflectional language: affixes (which usually encode more than one grammatical category) are attached to fixed stems to express gender, number, and case in adjectives, nouns, and pronouns, which is called declension; and person, number, tense, voice, mood, and aspect in verbs, which is called conjugation. There are five declensions (declinationes) of nouns and four conjugations of verbs. There are six noun cases: #nominative (used as the subject of the verb or the predicate nominative), #genitive (used to indicate relation or possession, often represented by the English of or the addition of s to a noun), #dative (used of the indirect object of the verb, often represented by the English to or for), #accusative (used of the direct object of the verb, or object of the preposition in some cases), #ablative (separation, source, cause, or instrument, often represented by the English by, with, from), #vocative (used of the person or thing being addressed). In addition, some nouns have a locative case used to express location (otherwise expressed by the ablative with a preposition such as in), but this survival from Proto-Indo-European is found only in the names of lakes, cities, towns, small islands, and a few other words related to locations, such as "house", "ground", and "countryside". Latin itself, being a very old language, is far closer to Proto-Indo-European than are most modern Western European languages; it has, in fact, about the same relationship with PIE as modern Italian or French has to Latin. There are six general tenses in Latin (technically they are tense/aspect/mood complexes). The indicative mood can be used with all of them. The subjunctive mood, however, has only present, imperfect, perfect, and pluperfect tenses. These tenses in the subjunctive mood do not completely correlate in meaning to the tenses in the indicative. The following examples are of the first conjugation verb "laudare" ("to praise") in the indicative mood and the active voice:
Primary sequence tenses
# present (laudo, "I praise") # imperfect (laudabam, "I was praising") # future (laudabo, "I shall praise," "I will praise")
Secondary sequence tenses
# perfect (laudavi, "I praised", "I have praised") # pluperfect (laudaveram, "I had praised") # future perfect (laudavero, "I shall have praised," "I will have praised") The future perfect tense can also imply a normal future idea (like in "When I will have run...") and so may also sometimes be included in the primary sequence.
Latin and Romance
After the collapse of the Roman Empire, Latin evolved into the various Romance languages. These were for many centuries only spoken languages, Latin still being used for writing. For example, Latin was the official language of Portugal until 1296 when it was replaced by Portuguese. The Romance languages evolved from Vulgar Latin, the spoken language of common usage, which in turn evolved from an older speech which also produced the formal classical standard. Latin and Romance differ (for example) in that Romance had distinctive stress, whereas Latin had distinctive length of vowels. In Italian and Sardo logudorese, there is distinctive length of consonants and stress, in Spanish only distinctive stress, and in French even stress is no longer distinctive. Another major distinction between Romance and Latin is that all Romance languages, excluding Romanian, have lost their case endings in most words except for some pronouns. Romanian retains a direct case (nominative/accusative), an indirect case (dative/genitive), and vocative. In Italy, Latin is still compulsory in secondary schools as Liceo Classico and Liceo Scientifico which are usually attended by people who aim to the highest level of education. In Liceo Classico Ancient Greek is a compulsory subject.
Latin and English
See Latin influence in English for a more complete exposition. English grammar is independent of Latin grammar, though prescriptive grammarians in English have been heavily influenced by Latin. Attempts to make English grammar follow Latin rules — such as the prohibition against the split infinitive — have not worked successfully in regular usage. However, as many as half the words in English were derived from Latin, including many words of Greek origin first adopted by the Romans, not to mention the thousands of French, hundreds of Spanish, Portuguese and Italian words of Latin origin that have also enriched English. During the 16th and on through the 18th century English writers created huge numbers of new words from Latin and Greek roots. These words were dubbed "inkhorn" or "inkpot" words (as if they had spilled from a pot of ink). Many of these words were used once by the author and then forgotten, but some remain. Imbibe, extrapolate, dormant and inebriation are all inkhorn terms carved from Latin words. In fact, the word etymology is derived from the Greek word etymologia, meaning "true sense of the word." Latin was once taught in many of the schools in Britain with academic leanings - perhaps 25% of the total [http://www.channel4.com/history/microsites/T/teachem2/thennow/]. However, the requirement for it was gradually abandoned in the professions such as the law and medicine, and then, from around the late 1960s, for admission to university. After the introduction of the Modern Language GCSE in the 1980s, it was gradually replaced by other languages, although it is now being taught by more schools along with other classical languages.
Latin education
The linguistic element of Latin courses offered in high schools or secondary schools, and in universities, is primarily geared toward an ability to translate Latin texts into modern languages, rather than using it in oral communication. As such, the skill of reading is heavily emphasized, whereas speaking and listening skills are barely touched upon. However, there is a growing movement, sometimes known as the Living Latin movement, whose supporters believe that Latin can, or should, be taught in the same way that modern "living" languages are taught, that is, as a means of both spoken and written communication. One of the most interesting aspects of such an approach is that it assists speculative insight into how many of the ancient authors spoke and incorporated sounds of the language stylistically; without understanding how the language is meant to be heard it is very difficult to identify patterns in Latin poetry. Institutions offering Living Latin instruction include the Vatican and the University of Kentucky. In Britain the Classical Association encourages this approach, and there has been something of a vogue for books describing the adventures of a mouse called Minimus. In the United States there is a thriving competitive organization for high school Latin students, the National Junior Classical League (the second-largest youth organization in the world after the Boy Scouts), backed up by the Senior Classical League for college students. Many would-be international auxiliary languages have been heavily influenced by Latin, and the moderately successful Interlingua considers itself to be the modernized and simplified version of the language (le latino moderne international e simplificate). Latin translations of modern literature such as Paddington Bear, Winnie the Pooh, Harry Potter and the Philosopher's Stone, Le Petit Prince, Max und Moritz, and The Cat in the Hat have also helped boost interest in the language.
See also

About the Latin language

- Latin grammar
- Latin spelling and pronunciation
- Latin declension
- Latin conjugation
- Latin alphabet
- List of Latin words with English derivatives
- Latin verbs with English derivatives
- Latin nouns with English derivatives
- ablative absolute
- Word order in Latin
About the Latin literary heritage

- Latin literature
- Romance languages
- Loeb Classical Library
- List of Latin phrases
- List of Latin proverbs
- Brocard
- List of Latin and Greek words commonly used in systematic names
- List of Latin place names in Europe
- Carmen Possum
Other related topics

- Roman Empire
- Internationalism
References

- Bennett, Charles E. Latin Grammar (Allyn and Bacon, Chicago, 1908)
- N. Vincent: "Latin", in The Romance Languages, M. Harris and N. Vincent, eds., (Oxford Univ. Press. 1990), ISBN 0195208293
- Waquet, Françoise, Latin, or the Empire of a Sign: From the Sixteenth to the Twentieth Centuries (Verso, 2003) ISBN 1859844022; translated from the French by John Howe.
- Wheelock, Frederic. Latin: An Introduction (Collins, 6th ed., 2005) ISBN 0060784237
External links

- [http://www.jambell.com/latin.html Latin Phrases for after dinner conversation (Thanks to Elaine Poole)]
- [http://www.ethnologue.com/show_language.asp?code=lat Ethnologue report for Latin]
- [http://forumromanum.org/literature/index.html Corpus Scriptorum Latinorum] is a comprehensive webography of Latin texts and their translations.
- [http://www.perseus.tufts.edu/ The Perseus Project] has many useful pages for the study of classical languages and literatures, including [http://www.perseus.tufts.edu/cgi-bin/resolveform?lang=Latin an interactive Latin dictionary].
- [http://lysy2.archives.nd.edu/cgi-bin/words.exe words by William whitaker] is a dictionary program online capable of looking up various word forms.
- [http://retiarius.org/ Retiarius.Org] includes a Latin text search engine.
- [http://www.nd.edu/~archives/latgramm.htm Latin-English dictionary and Latin grammar from U of Notre Dame]
- [http://latin-language.co.uk/ Latin language] History of Latin language, Latin texts with English translation and a collection of dictionaries.
- [http://augustinus.eresmas.net/scl/ Societas Circulorum Latinorum] gathers together Latin Circles all over the world.
- [http://www.learnlatin.tk LearnLatin.tk] - Free online course in Latin
- [http://www.latintests.net/ LatinTests.net] - Lets Latin learners test their grammar and vocabulary with self-checking quizzes.
- [http://thelatinlibrary.com/ The Latin Library] contains many Latin etexts
- [http://www.textkit.com/ Textkit] has Latin textbooks and etexts.
- [http://www.websters-online-dictionary.org/definition/Latin-english/ Latin–English Dictionary]: from Webster's Rosetta Edition.
- [http://www.language-reference.com/ Language reference] Cross-foreign-language lexicon powered by its own search engine. All cross combinations between Latin and French, German, Italian, Spanish.
- [http://comp.uark.edu/~mreynold/rhetor.html Rhetor by Gabriel Harvey] was originally published in 1577 and never again reprinted.
- [http://freewebs.com/omniamundamundis omniamundamundis] Latin hypertexts from fourteen ancient Roman authors.
- [http://www.saltspring.com/capewest/pron.htm Pronunciation of Biological Latin, Including Taxonomic Names of Plants and Animals]
- [http://www.yleradio1.fi/nuntii Nuntii Latini (News in Latin)], written and spoken (RealAudio) news in latin. Weekly review of world news in Classical Latin, the only international broadcast of its kind in the world, produced by YLE, the Finnish Broadcasting Company.
- [http://www.tranexp.com:2000/InterTran?url=http%3A%2F%2F&type=text&text=Replace%20Me&from=eng&to=ltt InterTran Latin], Translate from Latin to ENGLISH or vice versa.
- [http://www.latinvulgate.com Latin Vulgate] The Latin and English of the Old & New Testaments in parallel, along with the Complete Sayings of Jesus in parallel Latin and English. Category:Classical languages Category:Ancient languages Category:Fusional languages Category:Languages of Italy Category:Languages of Vatican City als:Latein zh-min-nan:Latin-gí ko:라틴어 ja:ラテン語 simple:Latin language th:ภาษาละติน

Electromagnetic spectrum

s
SX = Soft X-Rays
EUV = Extreme ultraviolet
NUV = Near ultraviolet
Visible light
NIR = Near infrared
MIR = Moderate infrared
FIR = Far infrared

Radio waves:
EHF = Extremely high frequency (Microwaves)
SHF = Super high frequency (Microwaves)
UHF = Ultrahigh frequency
VHF = Very high frequency
HF = High frequency
MF = Medium frequency
LF = Low frequency
VLF = Very low frequency
VF = Voice frequency
ELF = Extremely low frequency]] The electromagnetic spectrum is the range of all possible electromagnetic radiation. Also, the "electromagnetic spectrum" (usually just spectrum) of an object is the range of electromagnetic radiation that it emits, reflects, or transmits. The electromagnetic spectrum, shown in the table, extends from frequencies used in the electric power grid (at the long-wavelength end) to gamma radiation (at the short-wavelength end), covering wavelengths from thousands of kilometres down to fractions of the size of an atom, though in principle the spectrum is actually infinite. Electromagnetic energy at a particular wavelength λ (in vacuum) has an associated frequency ν and photon energy E. Thus, the electromagnetic spectrum may be expressed equally well in terms of any of these three quantities. They are related according to the equations: :

\lambda = \frac  \,\!

and :

E=h\nu \,\!

where:
- c is the speed of light, 299792458 m/s

(c \approx 3 \cdot 10^8 \ \mbox/\mbox = 300,000 \ \mbox/\mbox)

.
- h is Planck's constant,

(h \approx 6.626069 \cdot 10^ \ \mbox \cdot \mbox \approx 4.13567 \ \mathrm \mbox/\mbox)

Spectra of objects

Nearly all objects in the universe emit, reflect and/or transmit some light. The distribution of this light along the electromagnetic spectrum (called the spectrum of the object) is determined by the object's composition. Several types of spectra can be distinguished depending upon the nature of the radiation coming from an object:
- If the spectrum is composed primarily of thermal radiation emitted by the object itself, an emission spectrum occurs.
- Some bodies emit light more or less according to the blackbody spectrum.
- If the spectrum is composed of background light, parts of which the object transmits and parts of which it absorbs, an absorption spectrum occurs. Electromagnetic spectroscopy is the branch of physics that deals with the characterization of matter by its spectra.

Classification systems

While the classification scheme is generally accurate, in reality there is often some overlap between neighboring types of electromagnetic energy. For example, SLF radio waves at 60 Hz may be received and studied by astronomers, or may be ducted along wires as electric power. Also, some low-energy gamma rays actually have a longer wavelength than some high-energy X-rays. This is possible because "gamma ray" is the name given to the photons generated from nuclear decay or other nuclear and subnuclear processes, whereas X-rays on the other hand are generated by electronic transitions involving highly energetic inner electrons. Therefore the distinction between gamma ray and X-ray is related to the radiation source rather than the radiation wavelength. Generally, nuclear transitions are much more energetic than electronic transitions, so usually, gamma-rays are more energetic than X-rays. However, there are a few low-energy nuclear transitions (e.g. the 14.4 keV nuclear transition of Fe-57) that produce gamma rays that are less energetic than some of the higher energy X-rays. Use of the radio frequency spectrum is regulated by governments. This is called frequency allocation.

Electric energy

Electrical energy covers the low-frequency, long-wavelength end of the spectrum. The radiation is usually ducted along 2-wire and 3-wire transmission lines and sent to various devices besides antennas. At zero frequency the energy is emitted by batteries and DC power supplies, while at 50 Hz and 60 Hz it is produced by rotary magnetic generators and ducted through the international power grids. At frequencies between 20 Hz to 30 kHz the EM energy is translated to and from acoustic energy and is distributed over telephone lines, as well as being used to operate loudspeakers for public address or in music systems. Note that other than its frequency, there is no functional difference between the VHF energy guided along a television coaxial cable, versus the 60 Hz travelling along the cord leading to a light bulb. When connected to the appropriate antenna, both will radiate into space.

Radio frequency

telephone lines Radio waves generally are utilized by antennas of appropriate size, with wavelengths ranging from hundreds of meters to about one millimeter. They are used for transmission of data, via modulation. Television, mobile phones, wireless networking and amateur radio all use radio waves.

Microwaves

The super high frequency (SHF) and extremely high frequency (EHF) of Microwaves come next. Microwaves are waves which are typically short enough to employ tubular metal waveguides of reasonable diameter. Microwave energy is produced with klystron and magnetron tubes, and with solid state diodes such as Gunn and IMPATT devices. Microwaves are absorbed by molecules that have a dipole moment in liquids. In a microwave oven, this effect is used to heat food. Low-intensity microwave radiation is used in Wi-Fi. It should be noted that an average microwave oven in active condition is, in close range, powerful enough to cause interference with poorly shielded electromagnetic fields such as those found in mobile medical devices and cheap consumer electronics.

Terahertz radiation

This is a region of the light spectrum between far infrared and microwaves. Until recently, the range was rarely studied and few sources existed for microwave energy at the high end of the band (sub-millimeter waves or so-called terahertz waves), but applications are now appearing. The proposed WiMAX standard for wireless networking, a long-range enhancement of Wi-Fi, lies within this region. Scientists are also looking to apply Terahertz technology in the armed forces, where high frequency waves will be sent at enemy troops to incapacitate them.

Infrared radiation

The infrared part of the electromagnetic spectrum covers the range from roughly 300 GHz (1 mm) to 400 THz (750 nm). It can be divided into three parts:
- Far-infrared, from 300 GHz (1 mm) to 30 THz (10 μm). The lower part of this range may also be called microwaves. This radiation is typically absorbed by so-called rotational modes in gas-phase molecules, by molecular motions in liquids, and by phonons in solids. The water in the Earth's atmosphere absorbs so strongly in this range that it renders the atmosphere effectively opaque. However, there are certain wavelength ranges ("windows") within the opaque range which allow partial transmission, and can be used for astronomy. The wavelength range from approximately 200 μm up to a few mm is often referred to as "sub-millimeter" in astronomy, reserving far infrared for wavelengths below 200 μm.
- Mid-infrared, from 30 to 120 THz (10 to 2.5 μm). Hot objects (black-body radiators) can radiate strongly in this range. It is absorbed by molecular vibrations, that is, when the different atoms in a molecule vibrate around their equilibrium positions. This range is sometimes called the fingerprint region since the mid-infrared absorption spectrum of a compound is very specific for that compound.
- Near-infrared, from 120 to 400 THz (2,500 to 750 nm). Physical processes that are relevant for this range are similar to those for visible light.

Visible radiation (light)

Color	Wavelength interval	Frequency interval
violet	~ 380 to 430 nm	~ 790 to 700 THz
blue	~ 430 to 500 nm	~ 700 to 600 THz
cyan	~ 500 to 520 nm	~ 600 to 580 THz
green	~ 520 to 565 nm	~ 580 to 530 THz
yellow	~ 565 to 590 nm	~ 530 to 510 THz
orange	~ 590 to 625 nm	~ 510 to 480 THz
red	~ 625 to 740 nm	~ 480 to 405 THz
Continuous spectrum Image:Spectrum441pxWithnm.png The spectrum of visible light Designed for monitors with gamma 1.5.

After infrared comes visible light. This is the range in which the sun and stars similar to it emit most of their radiation. It is probably not a coincidence that the human eye is sensitive to the wavelengths that the sun emits most strongly. Visible light (and near-infrared light) is typically absorbed and emitted by electrons in molecules and atoms that move from one energy level to another. The light we see with our eyes is really a very small portion of the electromagnetic spectrum. A rainbow shows the optical (visible) part of the electromagnetic spectrum; infrared (if you could see it) would be located just beyond the red side of the rainbow with ultraviolet appearing just beyond the violet end.

Ultraviolet light

Next comes ultraviolet. This is radiation whose wavelength is shorter than the violet end of the visible spectrum. Being very energetic, UV can break chemical bonds, make molecules unusually reactive or ionize them, in general changing their mutual behavior. Sunburn, for example, is caused by the disruptive effects of UV radiation on skin cells, which can even cause skin cancer, if the radiation damages the complex DNA molecules in the cells (UV radiation is a proven mutagen). The Sun emits a large amount of UV radiation, which could quickly turn Earth into a barren desert, but most of it is absorbed by the atmosphere's ozone layer before reaching the surface.

X-rays

After UV come X-rays. Hard X-rays are of shorter wavelengths than soft X-rays. X-rays are used for seeing through some things and not others, as well as for high-energy physics and astronomy. Neutron stars and accretion disks around black holes emit X-rays, which enable us to study them.

Gamma rays

After hard X-rays come gamma rays. These are the most energetic photons, having no lower limit to their wavelength. They are useful to astronomers in the study of high-energy objects or regions and find a use with physicists thanks to their penetrative ability and their production from radioisotopes. The wavelength of gamma rays can be measured with high accuracy by means of Compton scattering. Note that there are no defined boundaries between the types of electromagnetic radiation. Some wavelengths have a mixture of the properties of two regions of the spectrum. For example, red light resembles infra-red radiation in that it can resonate some chemical bonds.

External links

- [http://www.ntia.doc.gov/osmhome/allochrt.html U.S. Frequency Allocation Chart] - Covering the range 3 kHz to 300 GHz (from Department of Commerce)
- [http://strategis.ic.gc.ca/epic/internet/insmt-gst.nsf/vwapj/spectallocation.pdf/%24FILE/spectallocation.pdf Canadian Table of Frequency Allocations] (from Industry Canada)
- [http://www.ofcom.org.uk/static/archive/ra/topics/spectrum-strat/future/strat02/strategy02app_b.pdf UK frequency allocation table] (from Ofcom, which inherited the Radiocommunications Agency's duties, pdf format)
- [http://www.scienceofspectroscopy.info The Science of Spectroscopy] - supported by NASA, includes OpenSpectrum, a Wiki-based learning tool for spectroscopy that anyone can edit
- [http://www.e-builds.com/EM%20spectrum/ An EM Spectrum Overview in Flash] by e-builds ja:電磁スペクトル

Diaphragm (optics)

al diaphragm opening is 4.375mm]] In optics, a diaphragm is an opening in the lightpath of a lens or objective that can regulate the amount of light that passes. The centre of the diaphragm coincides with the optical axis of the lens system. Normally it is shaped in a near-round fashion by a number of curved blades. Diaphragms usually have five to eight blades, depending on the intended uses, pricing and quality of the device in which it is used. Many cameras have an adjustable diaphragm to control the amount of light, which can also be regulated by adjusting the shutter time. The principle is identical to that of the iris in the human eye. A small diaphragm reduces the amount of light, but also reduces the influence of aberrations of the optical lens system and increases the depth of field. The reduced light intensity will however require the shutter time to be increased, which leads to increased blurring if the subject of the photograph or the camera moves during the exposure. The number of blades in a diaphragm has a direct relation with the appearance of the blurred out-of-focus areas in an image, also called Bokeh. The more blades a diaphragm has, the rounder and less polygon-shaped the opening will be. This results in softer and more gradually blurred out-of-focus areas. In a picture, the number of blades the diaphragm used has, can be guessed by counting the number of spikes converging from a light source or bright reflection. There are always twice as many spikes as there are blades. In case of an even number of blades, these spikes will overlap each other, so the number of spikes visible will be the number of spikes in de diaphragm used. This is most apparent in pictures taken in the dark with small bright spots, for example nightly cityscapes.

Shutter speed

settings can achieve unusual results]] In photography, shutter speed is the time for which the shutter is held open during the taking of a photograph to allow light to reach the film or imaging sensor (in a digital camera). In combination with variation of the lens aperture, this regulates how exposed the film will be or how much light the imaging sensor in a digital camera will receive. For a given exposure, a fast shutter speed demands a larger aperture to avoid under-exposure, just as a slow shutter speed is offset by a very small aperture to avoid over-exposure. Long shutter speeds are often used in low light condition, such as at night. Shutter speed is measured in seconds. A typical shutter speed for photographs taken in sunlight is 1/125th of a second. In addition to its effect on exposure, shutter speed changes the way movement appears in the picture. Very short shutter speeds are used to freeze fast-moving subjects, for example at sporting events. Very long shutter speeds are to intentionally blur a moving subject for artistic effect. In early days of photography, available shutter speeds were somewhat ad hoc. Following the adoption of a standardized way of representing aperture so that each major aperture interval exactly doubled or halved the amount of light entering the camera (f/2.8, f/4, f/5.6, f/8, f/11, f/16 etc.), a standardized 2:1 scale was adopted for shutter speed so that opening one aperture stop and reducing the shutter speed by one step resulted in the identical exposure. The agreed standard for shutter speeds is:
- 1/8000 s
- 1/4000 s
- 1/2000 s
- 1/1000 s
- 1/500 s
- 1/250 s
- 1/125 s
- 1/60 s
- 1/30 s
- 1/15 s
- 1/8 s
- 1/4 s
- 1/2 s
- 1 s
- B (for bulb) — keep the shutter open as long as the release lever is engaged.
- T — keep the shutter open until the lever is pressed again. This scale can be extended at either end in specialist cameras. The ability of the photographer to take images without noticeable blurring by camera movement is an important parameter in the choice of slowest possible shutter speed for a handheld camera. The rough guide used by most 35mm photographers is that the slowest possible shutter speed that can be used with care is the shutter speed numerically closest to the lens focal length. For example, for handheld use of a 35 mm camera with a 50 mm normal lens, the closest shutter speed is 1/60 s. For a free-standing, unsupported photographer it is usually necessary to use the next fastest shutter speed which would be 1/125 s in this case. With great care its possible to use 1/30s with the 50mm lens, or even slower speed especially with non-SLR cameras. Note that using this with "great care" would normally mean bracing the camera, arms, or body to minimise camera movement. If a shutter speed is too slow for hand holding, a camera support—usually a tripod—must be used. Other 35 mm handheld examples are:
- 28 mm wide angle lens, 1/30 s may be used with care, and 1/60 s is advised.
- 105 mm medium telephoto lens, 1/125 s may be used with care, and 1/250 s is advised.
- 300 mm long telephoto lens, 1/250 s may be used with care, and 1/500 s is advised.

Cinematographic Shutter Formulae

In cinematography, shutter speed is a function of the frame rate and shutter angle. Most motion picture film cameras use a rotating shutter with a shutter angle of 170 to 180 °, which leaves the film exposed for about 1/48 or 1/50 second at a standard 24 frame/s. Where E = Exposure, F = Frames per second, and S = Shutter opening: :

E = \frac

S = \frac

See also: exposure, shutter, f-number, exposure value

Additional Photos

Category:Photographic terms

Focus free lens

A focus free lens is a photographic lens whose focal point is fixed at its hyperfocal distance. Rather than having a method of determining the correct focusing distance and setting the lens to that focal point, a focus free lens relies on depth of field to produce acceptably sharp images. Most cameras with focus free lenses also have a relatively small aperture which increases the depth of field. Cameras with these lenses generally use a viewfinder for composition. The advantage of this design is that it can be produced very inexpensively, more so than automatic or manual systems. The system is also effectively automatic; the photographer need not worry about focusing. It can also be more predicable than automatic systems. The disadvantages are the fact that lenses of this type produces images that are less sharp than a lens that has been set to the best focal point for a given scene, and they are unable to produce sharp images of objects close to the camera, usually within 8-12 feet. The later limitation makes them unsuitable for portraits, as they cannot fill the frame of an image with a persons face and render it sharp at the same time. This limitation is likely to confuse inexperienced photographers. Focus free lenses are used in the lowest end and cheapest cameras; disposable and low-end point and shoot. They are usually wide angle with fixed aperture. Category:Photographic lenses

Scale-focus

Scale-focus or zone-focus is a type of focusing system used by many inexpensive cameras from the 1940s and 1950s. These cameras have an adjustable focus, but lack a focusing aid such as a rangefinder. You had to determine the distance to the subject and set the focus using a scale printed on the lens. If you are good at estimating distances, or have a tape measure at hand, you can get precise, sharp focus with one of these cameras.

Single-lens reflex camera

The single-lens reflex (SLR) is a type of camera that uses a movable mirror placed between the lens and the film to project the image seen through the lens to a matte focusing screen. Most SLRs use a pentaprism to observe the image via an eyepiece, but there are also other finder arrangements, such as the waist-level finder or porro prisms. The shutter in almost all contemporary SLRs sits just in front of the focal plane. If it does not, some other mechanism is required to ensure that no light reaches the film between exposures. For example, the Hasselblad 500C camera uses an auxiliary shutter blind in addition to its in-lens leaf shutter. Since the technology became widespread in the 1970s, SLRs have become the main type of camera used by dedicated amateur photographers and professionals.

Advantages of the SLR

Many of the advantages of SLR cameras derive from viewing the scene through the taking lens. There is no parallax error, and exact focus can be confirmed by eye—otherwise hard for macro photography and when using telephoto lenses. The true depth of field may be seen by stopping down to the taking aperture, possible on all but the cheapest cameras. Because of the SLR's versatility, most manufacturers have a vast range of lenses and accessories available. Only the Leica rangefinder cameras have a comparable system. Compared to most fixed-lens compact cameras, the most commonly used and cheapest SLR lenses offer a wider aperture range and larger maximum aperture (typically f/1.4 to f/1.8 for a 50 mm lens). This allows photographs to be taken in lower light conditions without flash, and allows a narrower depth of field, which is useful for blurring the background behind the subject, which makes the subject stand out better. This is commonly used in portrait photography.

Disadvantages

The most obvious disadvantage of the SLR is its greater weight and size than rangefinders of a similar technology level. The pentaprism and mirror box make the camera body larger. However, rangefinders have not advanced significantly since the 1970s, while modern SLRs use advanced automation and electronics to be smaller and plastics to save weight. The SLR's space-consuming mirror movement makes for difficulty in constructing wide angle lenses; rear lens elements cannot be close to the film plane. Retrofocus designs are required for wide-angle lenses; these are complex, large, and comparatively poorer in image quality. The reflex mirror must retract before the shutter can open, which introduces some delay. Autofocus systems on modern SLRs introduce further delay, especially in lower light. The mirror's movement also causes vibration and noise, a problem when using longer lenses and longer exposures. Technology has reduced but not eliminated this problem, which again is worse in larger formats. To combat this, higher-end cameras offer the ability to lock up the mirror before the shot is taken. This eliminates the vibration but blacks out the viewfinder. The SLR user cannot see anything outside the taking frame through the viewfinder, while with most rangefinder systems, this can be done. This helps in certain kinds of photography. Only higher-end SLRs show the full frame; typical coverage is 90%. Print labs generally crop an equivalent area, so it is less of a problem than it might otherwise be.

Format

SLR cameras have been produced for most film formats as well as digital formats. Most film SLRs use the 35 mm format, as this offers a good compromise between image quality, size, and cost. Medium format SLRs give a higher quality image when this is required. Digital SLRs (DSLRs) appeared on the market in the late 1990s and as of 2005 are used by many professional photographers as well as amateur enthusiasts. Early SLRs were built for large format photography, but this has largely died out. A small number of SLRs were built for the Advanced Photo System but this did not prove popular. SLRs were even built for film formats as small as 110, e.g. the Pentax Auto 110.

Common features

Other features found on many SLR cameras include through-the-lens (TTL) metering and sophisticated flash control. Many models on the market today actually measure the light that bounces off the film, and close the shutter when the picture has had enough exposure. Likewise, they can send out several short bursts of flash, determine the amount that comes back from the scene, then send out just the right amount of energy for a perfectly exposed photograph. Sophisticated cameras can even make it easy for the photographer to balance flash and available light for the desired look. While these capabilities are hardly unique to the SLR, manufacturers included them early on in the top models, whereas the best rangefinder cameras adopted such features later.

History

Large format SLR cameras were first built in the early years of the 20th century but were not very popular. Although the Soviet GOMZ sport (1935) was the first 35 mm SLR, it was the Ihagee Kine-Exakta (1936) that was truly influential. Further Exakta models, all with waist-level finders, were produced up to and during World War II. Meanwhile, Zeiss developed the eye-level viewfinder and pentaprism in prototype form, but the war intervened; in 1949 it saw production as the Contax S. It was the Japanese who developed the SLR further; the Asahi Optical Corporation was a pioneer in this, with 1952's Asahiflex. The Asahiflex IIB (1954) had the first auto-return mirror, while 1957's Asahi Pentax brought a fixed pentaprism, the right-hand thumb wind lever, and the overall control scheme of most manual-wind SLRs for the next 25 years or more. Modern-day market leaders Canon and Nikon introduced their first SLRs in 1959 (the Canonflex and F, respectively). The Nikon F was the camera that switched professional photographers to the 35 mm SLR. It was highly modular and versatile, and started the F series that continues to the present day. Through-the-lens (TTL) light metering came to the SLR in the early 1960s, with 1962's Topcon RE Super (spot metering) and 1964's Pentax Spotmatic (center-weighted average metering). Auto-exposure was next, introduced by Pentax in 1971's Electro Spotmatic and popularised with 1976's Canon AE-1, one of the best-selling cameras of all time. Full program auto-exposure soon followed. The 1970s and 1980s saw steadily increasing use of electronics, automation and minaturization, including integrated motor driven film advance and rewind functionality. Autofocus was the next major SLR revolution. The first autofocus SLR was 1981's Pentax ME-F, but it was 1985's Minolta Maxxum 7000 that shifted the market, and most competitors followed. Minolta, Canon and Contax chose to bring out a new, incompatible camera and lens system for autofocus, while Nikon and Pentax chose a backward-compatible method. Other manufacturers did not transition successfully to the autofocus era, and this led to an unrecoverable drop in sales. Only Leica's R system of completely manual-focus SLRs survives to the present day, although Pentax and Nikon still produce a few manual-focus models. The 1990s mostly saw further increases in automation and sophistication. The introduction of digital SLRs in the late 1990s was the next major market shift. Canon, Nikon, Pentax and Minolta have all introduced successful digital SLR ranges compatible with their film SLR systems, while Olympus has introduced a new digital-only SLR system, the Four Thirds system.

Notes

# See [http://www.mir.com.my/rb/photography/entry.htm Photography in Malaysia]'s [http://www.mir.com.my/rb/photography/htmls/contax_history/history2.htm Contax History, Part II].

Twin-lens reflex camera

A twin-lens reflex camera (TLR) is a type of camera with two objective lenses of the same focal length. One of the lenses is the photographic objective (the lens that takes the picture), while the other is used for the waist-level viewfinder system. In addition to the objective, the viewfinder consists of a 45-degree mirror (the reason for the word reflex in the name), a matte focusing screen at the top of the camera, and a pop-up hood surrounding it. The two objectives are connected, so that the focus shown on the focusing screen will be exactly the same as on the film. However, many inexpensive TLRs are fixed-focus models. Higher-end TLRs may have a pop-up magnifying glass to assist the user in focusing the camera. In addition, many have a "sports finder" consisting of a square hole punched in the back of the pop-up hood, and a knock-out in the front. Photographers can sight through these instead of using the matte screen. This is especially useful in tracking moving subjects such as animals, since the image on the matte screen is reversed left-to-right. Rollei Rolleiflex model TLRs have an additional feature for the "sports finder" that allows precise focusing. When the hinged front hood knock-out is moved to the sports finder position a secondary mirror swings down over the view screen to reflect the image to a secondary magnifier on the back of the hood, just below the direct view cutout. This permits precise focusing while using the sports finder feature. The magnified central image is reveresed both top to bottom and left to right. TLRs are different from single-lens reflex cameras (SLR) in several respects. First, unlike most SLRs, TLRs provide a continuous image on the finder screen. The view does not black out during exposure. Additionally, models with leaf shutters rather than focal-plane shutters can synchronize with flash at higher speeds than can SLRs. However, because the photographer views through one lens but takes the photograph through another, parallax error makes the photograph different from the view on the screen. This difference is negligible when the subject is far away, but is critical for nearby subjects. For accuracy in tabletop photography, in which the subject might be within a foot (30 cm) of the camera, devices are available that move the camera upwards so that the taking lens goes to the exact position that the viewing lens occupied. A primary advantage of the TLR is its simplicity as compared to the more common single-lens reflex cameras. The SLR must employ some method of blocking light from reaching the film during focusing, either with a focal plane shutter (most common) or with the reflex mirror itself. Both methods add significant noise to the camera's operation. Most TLRs use a leaf shutter in the lens. The only mechanical noise during exposure is from the shutter leaves opening and closing. The typical TLR is medium format, using 120 roll film with square 6 x 6 cm images. Presently, the Chinese Seagull and the German Rollei are in production, but in the past, many manufacturers made them. Models with the Mamiya, Minolta and Yashica brands are common on the used-camera market, and many other companies made TLRs that are now classics. There were smaller TLR models, using 127 roll film with square 4 x 4 cm images, most famous the "Baby" Rolleiflex and the Yashica 44. The TLR style was also popular in the 1950s for inexpensive fixed-focus cameras such as the Kodak Duaflex and Argus 75.

View camera

thumb The view camera is a type of camera with a very long history (some modern examples are often mistaken for antiques), but they are still used today by professional and amateur photographers who want full control of their images. The view camera is basically a light-tight assembly comprised of a flexible mid-section, or bellows, attached to a device that holds a film sheet, photo plate or digital imager at one end (the rear standard) and a similar one that holds the lens at the other end (the front standard). The front and rear standards are not fixed relative to each other (unlike most cameras). Movement of the front and rear standards allows the photographer to move the lens and film plane independently for precise control of the image's focus, depth of field and perspective.

View camera operation

In operation a view camera has the photographer open the shutter on the lens to compose and focus the image on a ground glass plate on the rear standard. As the ground glass image is sometimes difficult to view in bright light, the photographer may use a "dark cloth" to cover the rear of the camera to assist in composition. A Fresnel lens is also a great help as this lens considerably brightens the ground glass image (albeit with a slight loss of focusing accuracy), or a high quality loupe may be employed for critical focus on the ground glass. The lens may be stopped down to help gauge depth of field effects and vignetting, but is generally opened to its widest setting to aid in focus. To take the photograph, the ground glass, held within a metal frame, is displaced using springs and a film holder is inserted. The shutter is then closed and cocked, the shutter speed and aperture set, and the darkslide of the film holder removed, revealing the sheet of film. The shutter is then triggered, the exposure made, and the darkslide replaced into the film holder. Most sheet film holders are interchangeable between brands and models of view camera, adhering to a single standard. There are special film holders and accessories that fit in place of a standard film holder, such as Grafmatic, which could fit six sheets of film in the space of an ordinary two-sheet holder, and some light meters have an attachment that inserts into the film holder slot on the camera back that allows the photographer to measure light falling at a specific point on the film plane. The entire film holder/back assembly is often an industry standard Graflex back, removable so accessories like roll-film holders and digital imagers can be used without altering focus.

Types of view camera

Generally, view cameras are built for sheet film, one exposure for each sheet. These can be quite large, and are typically standardized to the following large film formats (measurements in inches): 4x5, 5x7, 4x10, 5x12, 8x10, 11x14, 7x17, 8x20, 12x20, 20x24, and 30x40. In Europe and Asia, the long side is often listed first when discussing sheet film size and the associated view camera equipment, albeit in inches rather than a metric measurement, ie. a 5x4 camera is identical to a 4x5 camera. Sometimes the closest equivalent in centimeters is used as well, ie. 9x12 or 12x9 for 4x5. Far and away the most popular formats are 4x5 and 8x10, with the majority of cameras and lenses designed for one or the other. Without modifying the camera (but with an inexpensive modification of the darkslide), a photographer can expose a half sheet of film at a time. While this could be useful for saving money, it's almost always instead a means of changing the format so that, for example, a 4x5 camera can take two 2x5 panoramic photos, an 8x10 can take two 4x10s etc. This is popular for landscape imagery, and in the past was common at banquets and similar functions. There are several varieties of view camera, engineered for different purposes and allowing different degrees of movement and portability. They include:
- Monorail Camera - This is the most common type of studio view camera, with the front and rear standards being mounted to a single rail that is fixed to a camera support. This design allows the most movement and flexibility, with both front and rear standards able to tilt, shift, rise, fall and swing in similar proportion. These are generally made of metal with leather or synthetic bellows, and are difficult to pack for travel. Sinar and Toyo are popular manufacturers of monorail view camera systems. ARCA-Swiss produces monorail cameras for field use in addition to models for the more conventional studio applications.
- Field Camera - These have the front and rear standard mounted to sliding rails on a flat bed that is fixed to a camera support. These cameras are designed to fold up into a small box for portability, and can be made of wood as well as composites like carbon fiber. The trade off is that the standards are not as mobile or as adjustable as with a monorail design, especially the rear standard, which may even be fixed and offer no movement. Their light weight and ease of packing and set-up are popular with landscape photographers. Extremely large cameras of this type, using 11x14 film and larger, or panoramic film sizes such as 4x10 or 8x20, are sometimes referred to as Banquet Cameras. Such cameras were once used to photograph large, posed groups of people to mark an occasion, such as those attending a banquet. Studio and Salon Cameras are similar in construction, but do not fold up for portability. Wisner and Tachihara are popular examples of modern Field Cameras at either end of the price spectrum.
- Press and Technical Cameras - These are very portable, but often have the least amount of usable movement of the three main types of view camera. Originally made for news photographers before roll film became popular, they are designed to fold up, with the lensboard in place, in less than a second. Some are equipped with rangefinders and viewfinders for hand-held work, and some antique models have focal plane shutters. These are typically made of machined and stamped metal, designed for daily use by working newsmen, so they are usually very robust, but also very heavy. The Speed Graphic in its many incarnations was the camera of choice for the American photojournalist in the Golden Age of Hollywood and in the Second World War, and used examples are still popular with photography students. Modern examples of Technical and Press View Cameras are still in production by Horseman, Wista and Linhof.

View camera movements

Press and Technical Cameras Photographers use view cameras to control focus and convergence of parallel lines. Image control is done by moving the front and/or rear standards. Movements are the ways the front and rear standards can be positioned to alter perspective and focus. The term can also refer to the mechanisms on the standards that allow the position to be achieved. Not all cameras have all movements available to both the front and rear standards, and some cameras have more movements available than others. In addition, some cameras are designed with mechanisms that make intricate movement combinations easier for the photographer to accomplish.

Rise and fall

Press and Technical Cameras Rise and fall are the movements of either the front or rear standard vertically along a line in a plane parallel to the film plane. Rise is a very important movement especially in architectural photography. Generally, the lens is moved vertically—either up or down—along the lens plane in order to change the portion of the image that will be captured on the film. The main effect of rise is to eliminate the optical illusion that tall buildings are “falling over backwards.” One way to get the image of a tall building to appear on the film is to point the camera upwards. This causes the top of the building to be optically further away that the bottom of the building. Objects further away tend to appear smaller than do objects that are near by. This phenomenon is called convergence. If we assume the two sides of the building are parallel to each other, then, like railroad tracks, the sides of the building will converge at the top. This effect is captured on film to give the appearance that the top of the building is smaller than the bottom of the building. The building will appear on film as though it were tipping over backwards. To correct for the convergence of parallel lines, the film plane must be kept parallel to the face of the building. This usually means the film plane is vertical. Unless the camera has a wide angle lens attached, some of the building will not be captured on film. Of course, the use of a wide angle lens is one way to keep the film plane vertical and still capture the entire height of the building but a lot of foreground will also be captured. Another method, the one available on large format cameras, is to raise the lens. Generally, the lens produces a larger image circle than the film can record. This is especially true of most large format lenses. By moving the lens up, the image is effectively moved down such that the top of the building can be captured on the film. In Figure a) below, the lens is in the “normal” position. Notice how much of the image is wasted. In Figure b), the lens has been shifted up. The top of the building, at the sacrifice of the green ground, is now inside the area captured on film. Press and Technical Cameras Press and Technical Cameras

Shift

Press and Technical Cameras Moving the standard left or right in relation to the film plane is called lens shift or simply shift. This movement is similar to the rise and fall movements but effect the image in the horizontal axis instead of the vertical axis. A possible use for shift is to remove the image of the camera from the final image when photographing directly into a mirrored surface.

Tilt

Press and Technical Cameras Altering the angle of the lens in relation to the film plane by tilting the lens standard back and forth is called lens tilt or just tilt. Tilt is another important movement and is especially useful in Landscape Photography. By using the Scheimpflug principle, the “plane of sharp focus” can be changed so that any plane can be brought into sharp focus. When the film plane and lens plane are parallel as is the case for most 35mm cameras, the plane of sharp focus will also be parallel to these two planes. If, however, the lens plane is tilted with respect to the film plane, the plane of sharp focus will also be tilted according to geometrical and optical properties. The three planes will intersect in a line below the camera for downward lens tilt. The tilted plane of sharp focus is very useful in that this plane can be made to coincide with a near and far object. Thus, both near and far objects on the plane will be in focus. This effect is often incorrectly thought of as increasing the depth of field. Depth of field is a function of the focal length, aperture, and image distance. But, tilt has a strong effect on the depth of field by drastically altering its shape. Without tilt, the limits of near and far acceptable focus are parallel to the plane of sharp focus as well as parallel to the film. With forward tilt, the plane of sharp focus tilts even more and the near and far limits of acceptable focus form a wedge shape (viewed from the side). Thus, the lens still sees a cone shaped portion of whatever is in front of it while the wedge of acceptable focus is now more closely aligned with this cone. Therefore, depending on the shape of the subject, a wider aperture can be used lessening concerns about slow shutter speeds and diffraction due to too small an aperture. Group f/64, the loose association of “West Coast” photographers such as Ansel Adams and Imogene Cunningham, must have selected their name with a certain amount of hyperbole in mind. They were not specifying that aperture as a silver bullet. The purpose of tilting is to achieve the desired depth of field using the widest possible aperture. Using a needlessly small aperture risks losing to diffraction and camera or subject motion what one gains from depth of field. Only testing a given scene, or experience, will show whether tilting is better than leaving the standards neutral and relying on the aperture alone to achieve the desired depth of field. If the scene is sharp enough at f/32 with 2 degrees of tilt but would need f/64 with zero tilt, then tilt is the solution. If another scene would need f/45 with or without tilt, then nothing is gained. With a forward tilt, the shape of the portion of a scene in acceptable focus is a wedge. Thus, the scene most likely to benefit from tilting is short in the front and expands to a greater height or thickness toward the horizon. A scene consisting of tall trees in the near, middle and far distance may not lend itself to tilting unless the photographer is willing to sacrifice either the top of the near trees and/or the bottom of the far trees. Assuming lens axis front tilt, here are the trade offs in choosing between a small degree of tilt (say less than 3) and a larger tilt: A small tilt causes a wider or fatter wedge but one that is far off axis from the cone of light seen by the lens. Conversely, a large tilt (say 10 degrees) causes the wedge to be more aligned with the view of the lens but with a narrower wedge. Thus, a modest tilt is often, or even usually, the best starting point. See Focusing the View Camera by Harold Merklinger. Small and medium format cameras have fixed bodies that do not allow for misalignment of the film and lens planes, intentionally or not. Tilt and shift lenses can be purchased from a number of lens makers that allow these cameras to have a small amount of adjustment, mostly rise and fall. High quality tilt/shift lenses are quite expensive. For the price of a new Nikon tilt/shift lens, one can purchase a good quality used large format camera that offers much more range of adjustment.

Swing

Scheimpflug principle Altering the angle of the lens standard in relation to the film plane by swiveling it from side to side is called swing. Swing is similar to Tilt but in the horizontal axis. Swing may be used to achieve sharp focus along the entire length of a picket fence, for example.

Back Tilt/Swing

Angular movements of the rear standard change the angle between the lens plane and the film plane just as front standard angular movements do. Although rear standard tilt will change the plane of sharp focus in the same manner as front standard tilt does, this is not usually the reason rear tilt/swing is used. When a lens is a certain distance (its focal length) away from the film, distant objects such as faraway mountains are in focus. Moving the lens farther from the film brings closer objects into focus. Tilting or swinging the film plane puts one side of the film farther from the lens than the center is and the opposite point of the film is therefore closer to the lens. One reason to swing or tilt the rear standard is to keep the film plane parallel to the face of the object being photographed. Another reason to swing or tilt the rear standard is to control convergence and, hence, perspective. By swinging the rear standard, perspective can be changed by making more distant objects appear closer, for example.

View camera lenses

A view camera lens typically consists of:
- A front lens element, sometimes referred to as a cell.
- A shutter, which consists of an electronic or spring-actuated iris which controls exposure duration. (On early lenses, air-actuated shutters were sometimes used, and others had no moving shutter at all, a simple lens cap was used instead.)
- The aperture diaphragm
- A lensboard
- A rear lens element (or cell). Almost any lens of the appropriate coverage area may be used with almost any view camera. All that is required is that the lens be mounted on a lensboard compatible with the camera. A lensboard is simply a flat board, typically square in shape and made of either metal or wood, designed to lock securely into the front standard of a particular view camera, typically engineered for quick removal and replacement for swapping lenses in the field. Not all lensboards work with all models of view camera, though some cameras may be designed to work with a common lensboard type. Lensboards usually come with a hole sized according to the shutter size, often called the Copal Number. Copal is the most popular maker of leaf shutt