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. In English, today's photographic devices 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 side, (see pinhole camera 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 in the Discovery and Origins section, it is also possible to project an up-side-up image. Another more portable type, 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 camerae obscurae use a lens rather than a pinhole because it allows a larger aperture, giving a usable brightness while maintaining focus.
Monday, October 15, 2007
Composition
n the visual arts, in particular painting, graphic design, and photography and sculpture composition is the plan, placement or arrangement of elements or ingredients in an art work. The selection and placement of elements within the work contributes to a response from the viewer, the work of art is said to be aesthetically pleasing to the eye if the elements within the work are arranged in a balanced compositional way (Dunstan, 1979). However there are artists who sole aim is to disrupt traditional composition and challenge the viewer to rethink balance and design elements within art works, for instance artists like Salvador Dali.
Basically the term composition means 'putting together', any work of art from music to writing is arranged or put together using conscious thought. The various elements in the overall design usually relate to each other and to the whole art work (Dunstan, p. 7, 1979). There are fundamentally two types of composition: informal, and the less frequently found formal or symmetrical. Composition is also related to artistic canon, for example, the draughting of a pleasing face. In graphic design and desktop publishing, composition is commonly referred to as page layout.
Basically the term composition means 'putting together', any work of art from music to writing is arranged or put together using conscious thought. The various elements in the overall design usually relate to each other and to the whole art work (Dunstan, p. 7, 1979). There are fundamentally two types of composition: informal, and the less frequently found formal or symmetrical. Composition is also related to artistic canon, for example, the draughting of a pleasing face. In graphic design and desktop publishing, composition is commonly referred to as page layout.
Gelatin-silver process
The gelatin-silver process is the photographic process used with currently available black-and-white films and printing papers. A suspension of silver salts in gelatin is coated onto acetate film or fiber-based or resin coated paper and allowed to dry (hence the term dry plate). These materials remain stable for months and years unlike the 'wet plate' materials that preceded them.
The Gelatin-Silver process was introduced by R. L. Maddox in 1871 with subsequent considerable improvements in sensitivity obtained by Charles Harper Bennet in 1878. Intense research in the last 125 years has led to current materials that exhibit low grain and high sensitivity to light.
When small crystals (called grains) of silver salts such as silver bromide and silver chloride are exposed to light, a few atoms of free metallic silver are liberated. These free silver atoms form the latent image. This latent image is relatively stable and will persist for some months without degradation provided the film is kept dark and cool. Films are developed using solutions that reduce the free silver atoms. An 'amplification' of the latent image occurs as the silver salts near the free silver atom are also reduced to metallic silver. The strength, temperature and time for which the developer is allowed to act allow the photographer to control the contrast of the final image. The development is then stopped by neutralizing the developer in a second bath.
Once development is complete, the undeveloped silver salts must be removed by fixing in sodium thiosulphate or ammonium thiosulphate, and then the film or paper must be washed in clean water. The final image consists of metallic silver embedded in the gelatin coating.
See photographic processes for older methods that have seen something of a come-back recently amongst art photographers.
The Gelatin-Silver process was introduced by R. L. Maddox in 1871 with subsequent considerable improvements in sensitivity obtained by Charles Harper Bennet in 1878. Intense research in the last 125 years has led to current materials that exhibit low grain and high sensitivity to light.
When small crystals (called grains) of silver salts such as silver bromide and silver chloride are exposed to light, a few atoms of free metallic silver are liberated. These free silver atoms form the latent image. This latent image is relatively stable and will persist for some months without degradation provided the film is kept dark and cool. Films are developed using solutions that reduce the free silver atoms. An 'amplification' of the latent image occurs as the silver salts near the free silver atom are also reduced to metallic silver. The strength, temperature and time for which the developer is allowed to act allow the photographer to control the contrast of the final image. The development is then stopped by neutralizing the developer in a second bath.
Once development is complete, the undeveloped silver salts must be removed by fixing in sodium thiosulphate or ammonium thiosulphate, and then the film or paper must be washed in clean water. The final image consists of metallic silver embedded in the gelatin coating.
See photographic processes for older methods that have seen something of a come-back recently amongst art photographers.
Gum printing
Gum printing is a way of making photographic reproductions without the use of silver halides. The process used salts of dichromate in common with a number of other related procceses such as sun printing.
When mixtures of mucilaginous, protein-containing materials together with soluble salts of dichromate are exposed to ultraviolet light, the protein content becomes tanned and resistant to solution in water. The untanned material can be washed away in warm water leaving a hardened, tanned protein negative.
Gum printing using a solution of gum arabic mixed with either potassium or ammonium dichromate. The higher the proportion of dichromate, the more sensitive the mixture. However, increasing the concentration of dichromate also reduces the contrast which is very low at best. The right concentration of dichromate is always a compromise between speed and contrast.
Using ammonium dichromate allows concentrations up to 15% of the active ingredient whereas potassium dichromate is limited to about 10%. Exceeding these concentrations results in deposits of chromic acid in the dried film which ruins any attempts at printing. The greatest sensitivity expressed as an ASA rating is estimated to be about ASA 0.003.
In gum printing, the gum-dichromate mixture is supplemented by high quality powered pigment. The resulting mucilaginous mixture is spread on a suitable base and allowed to dry in the dark. A contact negative the same size of the finished print is then placed on top of the dried coating and exposed to an ultraviolet light source, typically bright sunshine.
Often more than one negative is used to provide detail in all tonal ranges. Using multiple exposures requires very careful registration.
In exposing the paper, the thinnest parts of the negatives will allow the most exposure and cause the areas to be darker. The densest parts of the negative, which require more exposure, will have less colour.
The exposed print is then developed gradually in a succession of trays of still water (approximately ten minute intervals) at room temperature until the bath water is clear. The gum is soft and easily removed at this stage. Gentle agitation with a soft bristled brush can be used to remove pigment in highlights, give a painterly brushed appearance, and to release extra pigment from over-exposed areas.
When mixtures of mucilaginous, protein-containing materials together with soluble salts of dichromate are exposed to ultraviolet light, the protein content becomes tanned and resistant to solution in water. The untanned material can be washed away in warm water leaving a hardened, tanned protein negative.
Gum printing using a solution of gum arabic mixed with either potassium or ammonium dichromate. The higher the proportion of dichromate, the more sensitive the mixture. However, increasing the concentration of dichromate also reduces the contrast which is very low at best. The right concentration of dichromate is always a compromise between speed and contrast.
Using ammonium dichromate allows concentrations up to 15% of the active ingredient whereas potassium dichromate is limited to about 10%. Exceeding these concentrations results in deposits of chromic acid in the dried film which ruins any attempts at printing. The greatest sensitivity expressed as an ASA rating is estimated to be about ASA 0.003.
In gum printing, the gum-dichromate mixture is supplemented by high quality powered pigment. The resulting mucilaginous mixture is spread on a suitable base and allowed to dry in the dark. A contact negative the same size of the finished print is then placed on top of the dried coating and exposed to an ultraviolet light source, typically bright sunshine.
Often more than one negative is used to provide detail in all tonal ranges. Using multiple exposures requires very careful registration.
In exposing the paper, the thinnest parts of the negatives will allow the most exposure and cause the areas to be darker. The densest parts of the negative, which require more exposure, will have less colour.
The exposed print is then developed gradually in a succession of trays of still water (approximately ten minute intervals) at room temperature until the bath water is clear. The gum is soft and easily removed at this stage. Gentle agitation with a soft bristled brush can be used to remove pigment in highlights, give a painterly brushed appearance, and to release extra pigment from over-exposed areas.
Hand-colouring
Hand-colouring refers to any of a number of methods of manually adding colour to a black-and-white photograph or other image to heighten its realism. Typically, water-colours, oils and other paints or dyes are applied to the image surface using brushes, fingers, cotton swabs or airbrushes. Some photographic genres, particularly landscapes and portraits, have been more often hand-coloured than others, and hand-coloured photographs have been popular enough that some firms specialised in producing them.
Holography
Holography was invented in 1947 by Hungarian physicist Dennis Gabor (1900–1979), work for which he received the Nobel Prize in physics in 1971. The discovery was an unexpected result of research into improving electron microscopes at the British Thomson-Houston Company in Rugby, England. The British Thomson-Houston company filed a patent on 1947-12-17 (and received patent GB685286), but the field did not really advance until the development of the laser in 1960.
The first holograms that recorded 3D objects were made by Emmett Leith and Juris Upatnieks in University of Michigan, USA in 1963 and Yuri Denisyuk in the Soviet Union.
Several types of hologram can be made. Transmission holograms, such as those produced by Leith and Upatnieks, are viewed by shining laser light through them and looking at the reconstructed image from the side of the hologram opposite the source. A later refinement, the "rainbow transmission" hologram allows more convenient illumination by white light rather than by lasers or other monochromatic sources. Rainbow holograms are commonly seen today on credit cards as a security feature and on product packaging. These versions of the rainbow transmission hologram are commonly formed as surface relief patterns in a plastic film, and they incorporate a reflective aluminium coating which provides the light from "behind" to reconstruct their imagery.
Another kind of common hologram, the reflection or Denisyuk hologram, is capable of multicolour image reproduction using a white light illumination source on the same side of the hologram as the viewer.
One of the most promising recent advances in the short history of holography has been the mass production of low-cost solid-state lasers - typically used by the millions in DVD recorders and other applications, but which are sometimes also useful for holography. These cheap, compact, solid-state lasers can under some circumstances compete well with the large, expensive gas lasers previously required to make holograms, and are already helping to make holography much more accessible to low-budget researchers, artists, and dedicated hobbyists.
The first holograms that recorded 3D objects were made by Emmett Leith and Juris Upatnieks in University of Michigan, USA in 1963 and Yuri Denisyuk in the Soviet Union.
Several types of hologram can be made. Transmission holograms, such as those produced by Leith and Upatnieks, are viewed by shining laser light through them and looking at the reconstructed image from the side of the hologram opposite the source. A later refinement, the "rainbow transmission" hologram allows more convenient illumination by white light rather than by lasers or other monochromatic sources. Rainbow holograms are commonly seen today on credit cards as a security feature and on product packaging. These versions of the rainbow transmission hologram are commonly formed as surface relief patterns in a plastic film, and they incorporate a reflective aluminium coating which provides the light from "behind" to reconstruct their imagery.
Another kind of common hologram, the reflection or Denisyuk hologram, is capable of multicolour image reproduction using a white light illumination source on the same side of the hologram as the viewer.
One of the most promising recent advances in the short history of holography has been the mass production of low-cost solid-state lasers - typically used by the millions in DVD recorders and other applications, but which are sometimes also useful for holography. These cheap, compact, solid-state lasers can under some circumstances compete well with the large, expensive gas lasers previously required to make holograms, and are already helping to make holography much more accessible to low-budget researchers, artists, and dedicated hobbyists.
Kirlian photography
Kirlian photography refers to a form of contact print photography, theoretically associated with high-voltage. It is named after Semyon Kirlian, who in 1939 accidentally discovered that if an object on a photographic plate is connected to a source of high voltage, small corona discharges (created by the strong electric field at the edges of the object) create an image on photographic plate.
Kirlian photography is completely different from "Aura photography," in which a colorful image is produced of a persons face and upper torso, using various methods of biofeedback. People commonly use the term "Kirlian photography" to erroneously refer to "Aura photography," and vice-versa. The terms have almost become interchangeable, even though the techniques are completely different. This leads to confusion among those who not familiar with the two different techniques. The Kirlian technique is contact photography, in which the subject is in direct contact with the film which is placed upon a metal plate that is charged with high voltage, high frequency electricity. In Aura Photography, no high voltage is involved as with the Kirlian technique, and no direct contact with the film is made. The images made with an Aura camera do not result from coronal discharge, the colors are projected with fiber optics.
Kirlian's work, from 1939 onward, involved an independent rediscovery of a phenomenon and technique variously called "electrography," "electrophotography," and "corona discharge photography." The underlying physics (which makes xerographic copying possible) was explored as early as 1777 by Georg Christoph Lichtenberg (see Lichtenberg figures). Later workers in the field included Nikola Tesla; various other individuals explored the effect in the later 19th and early 20th centuries. Yet Kirlian took the development of the effect further than any of his predecessors.
In controversial metaphysical contexts, Kirlian photography, Kirlian energy, and so on, are sometimes referred to as just "Kirlian." Kirlian made controversial claims that his method showed proof of supernatural auras, said to resemble a rough outline of the object like a colorful halo. One of the more striking aspects of Kirlian photography is its reputed ability to illuminate the acupuncture points of the human body. An experiment advanced as evidence of energy fields generated by living entities involves taking Kirlian contact photographs of a picked leaf at set periods, its gradual withering being said to correspond with a decline in the strength of the aura. Scientifically, it is considered more likely that as the leaf loses moisture it becomes less electrically conductive, causing a gradual weakening of the electrical field at the drier edges of the leaf.
Kirlian photography is completely different from "Aura photography," in which a colorful image is produced of a persons face and upper torso, using various methods of biofeedback. People commonly use the term "Kirlian photography" to erroneously refer to "Aura photography," and vice-versa. The terms have almost become interchangeable, even though the techniques are completely different. This leads to confusion among those who not familiar with the two different techniques. The Kirlian technique is contact photography, in which the subject is in direct contact with the film which is placed upon a metal plate that is charged with high voltage, high frequency electricity. In Aura Photography, no high voltage is involved as with the Kirlian technique, and no direct contact with the film is made. The images made with an Aura camera do not result from coronal discharge, the colors are projected with fiber optics.
Kirlian's work, from 1939 onward, involved an independent rediscovery of a phenomenon and technique variously called "electrography," "electrophotography," and "corona discharge photography." The underlying physics (which makes xerographic copying possible) was explored as early as 1777 by Georg Christoph Lichtenberg (see Lichtenberg figures). Later workers in the field included Nikola Tesla; various other individuals explored the effect in the later 19th and early 20th centuries. Yet Kirlian took the development of the effect further than any of his predecessors.
In controversial metaphysical contexts, Kirlian photography, Kirlian energy, and so on, are sometimes referred to as just "Kirlian." Kirlian made controversial claims that his method showed proof of supernatural auras, said to resemble a rough outline of the object like a colorful halo. One of the more striking aspects of Kirlian photography is its reputed ability to illuminate the acupuncture points of the human body. An experiment advanced as evidence of energy fields generated by living entities involves taking Kirlian contact photographs of a picked leaf at set periods, its gradual withering being said to correspond with a decline in the strength of the aura. Scientifically, it is considered more likely that as the leaf loses moisture it becomes less electrically conductive, causing a gradual weakening of the electrical field at the drier edges of the leaf.
Post-mortem photography
Post-Mortem photography involved photographing the deceased. While an unusual practice by modern standards, this type of photography was fairly common up into the late 19th century and early 20th century. During these times, early death, especially the early death of a child, was much more commonplace, and photography was still somewhat of a novelty. This lent societal acceptance to the practice of photographing the dead, often with some of the living family members included in the portrait.
This practice may have been somewhat more common in Europe, but was widely practiced in the USA.
Variations on this practice included photographing a family portrait with a “shrine” to the dead family member included in the pose or posing next to the grave of the departed. Items of the departed member, such as photographs, toys and flowers might all be included in the composition.
This practice may have been somewhat more common in Europe, but was widely practiced in the USA.
Variations on this practice included photographing a family portrait with a “shrine” to the dead family member included in the pose or posing next to the grave of the departed. Items of the departed member, such as photographs, toys and flowers might all be included in the composition.
North American Nature Photography Association
The North American Nature Photography Association or NANPA is an organization dedicated to photography of nature. It has several categories of membership, including discounts for students. It annually sponsors many events and conferences, such as NANPA Road Shows, in the United States. Its Foundation, initially established in 1997, awards scholarships, operates blinds for wildlife photography, and organizes funds in memory of deceased photographers and others. NANPA also markets books of interest to members, including those by members, through Amazon.com.
Photograph
A photograph (often shortened to photo) is an image created by light falling on a light-sensitive surface, usually photographic film or an electronic imager such as a CCD or a CMOS chip. Most photographs are created using a camera, which uses a lens to focus the scene's visible wavelengths of light into a reproduction of what the human eye would see. The process of creating photographs is called photography.
Motion pictures, such as film or video, are generally considered to be sequences of photographs.
Motion pictures, such as film or video, are generally considered to be sequences of photographs.
Print permanence
Print permanence refers to the longevity of printed material, especially photographs, and Preservation Issues. Over time, the density, color balance, lustre and other qualities of a print will degrade. The rate at which deterioration occurs depends primarily on two main factors: the print itself, that is, the colorants used to form the image and the medium on which image resides, and the type of environment the print is exposed to.
Vignetting
In photography and optics, vignetting is a reduction in image brightness in the image periphery compared to the image center.
Although vignetting is normally unintended and undesired, it is sometimes purposely introduced for creative effect, such as to draw attention to the center of the frame. A photographer may deliberately choose a lens which is known to produce vignetting. It can also be produced with the use of special filters or post-processing procedures.
Although vignetting is normally unintended and undesired, it is sometimes purposely introduced for creative effect, such as to draw attention to the center of the frame. A photographer may deliberately choose a lens which is known to produce vignetting. It can also be produced with the use of special filters or post-processing procedures.
Film base
A film base is a transparent substrate which acts as a support medium for the photosensitive emulsion that lies atop it. Despite the numerous layers and coatings associated with the emulsion layer, the base generally accounts for the vast majority of the thickness of any given film stock. Historically there have been three major types of film base in use: cellulose nitrate, cellulose acetate (cellulose diacetate, cellulose acetate propionate, cellulose acetate butyrate, and cellulose triacetate), and polyethylene trephthalate polyester (Kodak trade-name: ESTAR).
Film format
A film format is a technical definition of a set of standard characteristics regarding image capture on photographic film, for either stills or movies. It can also apply to projected film, either slides or movies. The primary characteristic of a film format is its size and shape.
In the case of motion picture film, the format may also encompass audio parameters (though often not). Other characteristics usually include the film gauge, pulldown method, lens anamorphosis (or lack thereof), and film gate or projector aperture dimensions, all of which need to be defined for photography as well as projection, as they may differ.
In the case of motion picture film, the format may also encompass audio parameters (though often not). Other characteristics usually include the film gauge, pulldown method, lens anamorphosis (or lack thereof), and film gate or projector aperture dimensions, all of which need to be defined for photography as well as projection, as they may differ.
Film holder
A film holder is a device which holds one or more pieces of photographic film, for insertion into a camera or optical scanning device such as a dedicated film scanner or a flatbed scanner with film scanning capabilities. The widest usage of the term refers to a device which holds sheet film for use in large format cameras, but can also be used to refer to various interchangeable devices used by medium format camera systems.
Film scanner
A film scanner is a device made for scanning photographic film directly into a computer without the use of any intermediate printmaking. They provide several benefits over using a flatbed scanner to scan in a print of any size - the photographer has direct control over cropping and aspect ratio from the original unmolested image on film, and many film scanners come with specialized software or hardware designed to remove scratches, film grain, and improve color reproduction from old negatives.
Film scanners can accept either strips of 35 mm or 120 film, or individual slides. Low-end scanners typically only take 35mm film strips, while medium- and high-end film scanners often have interchangeable film loaders. This allows the one scanning platform to be used for different sizes and packaging. For example, some allow microscope slides to be loaded for scanning, while mechanised slide loaders allow many individual slides to be batch scanned unattended.
Film scanners can accept either strips of 35 mm or 120 film, or individual slides. Low-end scanners typically only take 35mm film strips, while medium- and high-end film scanners often have interchangeable film loaders. This allows the one scanning platform to be used for different sizes and packaging. For example, some allow microscope slides to be loaded for scanning, while mechanised slide loaders allow many individual slides to be batch scanned unattended.
Photographic filter
In photography, a filter is a camera accessory consisting of an optical filter that can be inserted in the optical path. The filter can be a square or rectangle shape mounted in a holder accessory, or, more commonly, a glass or plastic disk with a metal or plastic ring frame, which can be screwed in front of the lens.
Filters allow added control for the photographer of the images being produced. Sometimes they are used to make only subtle changes to images; other times the image would simply not be possible without them.
The negative aspects of using filters, though often negligible, include the possibility of loss of image definition if using dirty or scratched filters, and increased exposure required by the reduction in light transmitted. The former is best avoided by careful use and maintenance of filters, while the latter is a matter of technique; it usually will not be a problem if planned out properly, but in some situations does make filter use impractical.
Filters allow added control for the photographer of the images being produced. Sometimes they are used to make only subtle changes to images; other times the image would simply not be possible without them.
The negative aspects of using filters, though often negligible, include the possibility of loss of image definition if using dirty or scratched filters, and increased exposure required by the reduction in light transmitted. The former is best avoided by careful use and maintenance of filters, while the latter is a matter of technique; it usually will not be a problem if planned out properly, but in some situations does make filter use impractical.
Flash
In photography, a flash is a device that produces an instantaneous flash of artificial light (typically around 1/3000 of a second) at a color temperature of about 5500K to help illuminate a scene. While flashes can be used for a variety of reasons (e.g. capturing quickly moving objects, creating a different temperature light than the ambient light) they are mostly used to illuminate scenes that do not have enough available light to adequately expose the photograph. The term flash can either refer to the flash of light itself, or as a colloquialism for the electronic flash unit which discharges the flash of light. The vast majority of flash units today are electronic, having evolved from single-use flash-bulbs and flammable powders.
In lower-end consumer photography, flash units are commonly built directly into the camera, while higher-end cameras allow separate flash units to be mounted via a standardized accessory mount bracket. In professional studio photography, flashes often take the form of large, standalone units, or studio strobes, that are powered by special battery packs and synchronized with the camera from either a flash synchronization cable, radio transmitter, or are light-triggered, meaning that only one flash unit needs to be synchronized with the camera, which in turn triggers the other units.
In lower-end consumer photography, flash units are commonly built directly into the camera, while higher-end cameras allow separate flash units to be mounted via a standardized accessory mount bracket. In professional studio photography, flashes often take the form of large, standalone units, or studio strobes, that are powered by special battery packs and synchronized with the camera from either a flash synchronization cable, radio transmitter, or are light-triggered, meaning that only one flash unit needs to be synchronized with the camera, which in turn triggers the other units.
Gray card
Gray cards are used, together with reflective light meters, as a way to produce consistent images in film and photography.
A gray card is a flat object of a neutral gray color that derives from a flat reflectance spectrum. Typical examples are the Kodak R-27 set, which contains 2 8x10" cards and one 4x5" card which have 18% reflectance across the visible spectrum, and a white reverse side which has 90% reflectance, and QPcard 101 and 102 with not only gray surfaces but also white and dark gray. Note that flat spectral reflectance is a stronger condition than appearing neutral; this flatness ensures that the card appears neutral under any illuminant.
A gray card is a flat object of a neutral gray color that derives from a flat reflectance spectrum. Typical examples are the Kodak R-27 set, which contains 2 8x10" cards and one 4x5" card which have 18% reflectance across the visible spectrum, and a white reverse side which has 90% reflectance, and QPcard 101 and 102 with not only gray surfaces but also white and dark gray. Note that flat spectral reflectance is a stronger condition than appearing neutral; this flatness ensures that the card appears neutral under any illuminant.
Monopod
A monopod, also called a unipod, is a pole used to help support cameras, video cameras (or, less frequently, binoculars). It allows a still camera to be held steadier, allowing the photographer to take sharp pictures at slower shutter speeds, and/or with longer focal length lenses. In the case of video, it reduces camera shake and therefore most of the resulting small random movements. When used by itself, it eliminates camera shake in the vertical plane. When used in combination with leaning against a large object, a bipod is formed; this can also eliminate horizontal motion.
Monopods are usually made to fold, or "telescope," when not in use, allowing them to be transported and stored more easily.
Unlike a tripod, monopods cannot support a camera independently. In the case of still cameras this limits the shutter speed that can be used. They still allow lower shutter speeds than hand holding, and are easier to carry and use than a tripod.
Many monopods can also be used as a "chestpod," or "beltpod," meaning that the foot of the monopod (sometimes with a special adapter) can rest on the belt, waist, or chest, of the photographer. The result is that the camera is held more steadily than by hand alone (though not as steadily as when the foot is planted on the ground), and the camera/monopod is completely mobile, travelling with the photographer's movements. This is similar to a finnstick.
In terms of mobility vs. stability, generally if stability increases, mobility decreases. From most stable/least mobile to least stable/most mobile: tripod/tablepod/resting on surface of some sort, monopod, chestpod, handheld.
Monopods are usually made to fold, or "telescope," when not in use, allowing them to be transported and stored more easily.
Unlike a tripod, monopods cannot support a camera independently. In the case of still cameras this limits the shutter speed that can be used. They still allow lower shutter speeds than hand holding, and are easier to carry and use than a tripod.
Many monopods can also be used as a "chestpod," or "beltpod," meaning that the foot of the monopod (sometimes with a special adapter) can rest on the belt, waist, or chest, of the photographer. The result is that the camera is held more steadily than by hand alone (though not as steadily as when the foot is planted on the ground), and the camera/monopod is completely mobile, travelling with the photographer's movements. This is similar to a finnstick.
In terms of mobility vs. stability, generally if stability increases, mobility decreases. From most stable/least mobile to least stable/most mobile: tripod/tablepod/resting on surface of some sort, monopod, chestpod, handheld.
Movie projector
A movie projector is an opto-mechanical device for displaying moving pictures by projecting them on a projection screen. Most of the optical and mechanical elements, except for the illumination and sound devices, are present in movie cameras.
Photographic film
Photographic film is a sheet of plastic (polyester, nitrocellulose or cellulose acetate) coated with an emulsion containing light-sensitive silver halide salts (bonded by gelatin) with variable crystal sizes that determine the sensitivity, contrast and resolution of the film. When the emulsion is sufficiently exposed to light (or other forms of electromagnetic radiation such as X-rays), it forms a latent (invisible) image. Chemical processes can then be applied to the film to create a visible image, in a process called film developing.
In black-and-white photographic film there is usually one layer of silver salts. When the exposed grains are developed, the silver salts are converted to metallic silver, which block light and appear as the black part of the film negative.
Color film uses at least three layers. Dyes, which adsorb to the surface of the silver salts, make the crystals sensitive to different colors. Typically the blue-sensitive layer is on top, followed by the green and red layers. During development, the exposed silver salts are converted to metallic silver, just as with black and white film. But in a color film, the by-products of the development reaction simultaneously combine with chemicals known as color couplers that are included either in the film itself or in the developer solution to form colored dyes. Because the by-products are created in direct proportion to the amount of exposure and development, the dye clouds formed are also in proportion to the exposure and development. Following development, the silver is converted back to silver salts in the bleach step. It is removed from the film in the fix step. This leaves behind only the formed color dyes, which combine to make up the colored visible image.
Newer color films, like Kodacolor II, have as many as 12 emulsion layers, with upwards of 20 different chemicals in each layer.
Because photographic film is widespread in the production of motion pictures, or movies, these are also known as films.
In black-and-white photographic film there is usually one layer of silver salts. When the exposed grains are developed, the silver salts are converted to metallic silver, which block light and appear as the black part of the film negative.
Color film uses at least three layers. Dyes, which adsorb to the surface of the silver salts, make the crystals sensitive to different colors. Typically the blue-sensitive layer is on top, followed by the green and red layers. During development, the exposed silver salts are converted to metallic silver, just as with black and white film. But in a color film, the by-products of the development reaction simultaneously combine with chemicals known as color couplers that are included either in the film itself or in the developer solution to form colored dyes. Because the by-products are created in direct proportion to the amount of exposure and development, the dye clouds formed are also in proportion to the exposure and development. Following development, the silver is converted back to silver salts in the bleach step. It is removed from the film in the fix step. This leaves behind only the formed color dyes, which combine to make up the colored visible image.
Newer color films, like Kodacolor II, have as many as 12 emulsion layers, with upwards of 20 different chemicals in each layer.
Because photographic film is widespread in the production of motion pictures, or movies, these are also known as films.
Photographic lens
A photographic lens (also known as objective lens or photographic objective) is an optical lens or assembly of lenses used in conjunction with a camera body and mechanism to make images of objects either on photographic film or on other media capable of storing an image chemically or electronically.
While in principle a simple convex lens will suffice, in practice a compound lens made up of a number of optical lens elements is required to correct (as much as possible) the many optical aberrations that arise. Some aberrations will be present in any lens system. It is the job of the lens designer to balance these out and produce a design that is suitable for photographic use and possibly mass production.
There is no difference in principle between a lens used for a camera, a telescope, a microscope, or other apparatus, but the detailed design and construction are different.
A lens may be permanently fixed to a camera, or it may be interchangeable with lenses of different focal lengths, apertures, and other properties.
While in principle a simple convex lens will suffice, in practice a compound lens made up of a number of optical lens elements is required to correct (as much as possible) the many optical aberrations that arise. Some aberrations will be present in any lens system. It is the job of the lens designer to balance these out and produce a design that is suitable for photographic use and possibly mass production.
There is no difference in principle between a lens used for a camera, a telescope, a microscope, or other apparatus, but the detailed design and construction are different.
A lens may be permanently fixed to a camera, or it may be interchangeable with lenses of different focal lengths, apertures, and other properties.
Slide projector
A slide projector is an opto-mechanical device to view photographic slides. It has four main elements: a fan-cooled electric light bulb or other light source, a reflector and "condensing" lens to direct the light to the slide, a holder for the slide and a focusing lens. A flat piece of heat absorbing glass is often placed in the light path between the condensing lens and the slide, to avoid damaging the latter. This glass transmits visible wavelengths but absorbs infrared. Light passes through the transparent slide and lens, and the resulting image is enlarged and projected onto a perpendicular flat screen so the audience can view its reflection. Alternatively the image may be projected onto a translucent "rear projection" screen, often used for continuous automatic display for close viewing. This form of projection also avoids the audience's interrupting the light stream or bumping into the projector.
Slide projectors were common in the 1950s and 1960s as a form of entertainment; family members and friends would gather to view slideshows.
In-home photographic slides and slide projectors have largely been replaced by low cost paper prints, digital cameras, DVD media, video display monitors and digital projectors.
As of October 2004, Kodak no longer manufactures slide projectors. It is also increasingly difficult in some countries to locate photo processors who will process slide film.
Slide projectors were common in the 1950s and 1960s as a form of entertainment; family members and friends would gather to view slideshows.
In-home photographic slides and slide projectors have largely been replaced by low cost paper prints, digital cameras, DVD media, video display monitors and digital projectors.
As of October 2004, Kodak no longer manufactures slide projectors. It is also increasingly difficult in some countries to locate photo processors who will process slide film.
Still camera
A still camera is a type of camera used to take photographs. Traditional cameras capture light onto photographic film. Digital cameras use electronics, usually a charge coupled device (CCD) to store digital images in computer memory inside the camera, which can be transferred to a computer for later processing.
Toy camera
Toy cameras are simple, inexpensive film box cameras made almost entirely out of plastic, often including the lens. The term is misleading, since they are not 'toys' in the sense that these cameras are actually capable of taking photographs. Many were made to be given away as novelties or prizes. The Diana, an inexpensive 1960s 4x4cm novelty box camera from Hong Kong, is typically the camera most associated with the term 'toy camera'. Other cameras, such as the LOMO LC-A, Lubitel, and Holga, while originally intended as consumer, mass-market cameras, have also become identified with the term.
Many professional photographers have utilized toy cameras and the often strange optical effects of their inexpensive lenses to take award-winning photographs. Toy camera photography has been widely exhibited at many popular art shows, such as the annual Krappy Kamera® show at the Soho Photo Gallery in the TriBeCa neighborhood of New York City. Various publications such as Photography magazine have extolled the virtues of the Diana camera in its own right as an "art" producing image maker. Several books have also featured the work of toy cameras, such as "The Diana Show", "Iowa", and "Angels at the Arno".
Many professional photographers have utilized toy cameras and the often strange optical effects of their inexpensive lenses to take award-winning photographs. Toy camera photography has been widely exhibited at many popular art shows, such as the annual Krappy Kamera® show at the Soho Photo Gallery in the TriBeCa neighborhood of New York City. Various publications such as Photography magazine have extolled the virtues of the Diana camera in its own right as an "art" producing image maker. Several books have also featured the work of toy cameras, such as "The Diana Show", "Iowa", and "Angels at the Arno".
Tripod
Tripods are used for both still and motion photography. A tripod of some sort is often necessary for professional photography as well as certain video uses; HDTV video in particular, due to peculiarities inherent in the MPEG-2 algorithms used, tends to be almost unwatchable without some sort of stabilization. Tripods are also used to support small to medium-sized telescopes, large firearms, and similar applications.
View camera
is a type of camera first developed in the era of the Daguerreotype and still in use today, though with many refinements. It comprises a flexible bellows which forms a light-tight seal between two adjustable standards one of which holds a lens, and the other a viewfinder or a photographic film holder.
The bellows is a flexible, accordion-pleated box, which encloses the space between the lens and film, and has the ability to flex to accommodate the movements of the standards.
The front standard is a board at the front of the camera which holds the lens and, usually, a shutter.
At the other end of the bellows, the rear standard is a frame which holds a ground glass, used for focusing and composing the image before exposure, which is replaced by a holder containing the light-sensitive film, plate, or image sensor for exposure. The front and rear standards can move in various ways relative to each other, unlike most other types of camera, giving control over focus, depth of field and perspective.
The camera must have some means of support, usually provision for mounting it on a tripod.
The bellows is a flexible, accordion-pleated box, which encloses the space between the lens and film, and has the ability to flex to accommodate the movements of the standards.
The front standard is a board at the front of the camera which holds the lens and, usually, a shutter.
At the other end of the bellows, the rear standard is a frame which holds a ground glass, used for focusing and composing the image before exposure, which is replaced by a holder containing the light-sensitive film, plate, or image sensor for exposure. The front and rear standards can move in various ways relative to each other, unlike most other types of camera, giving control over focus, depth of field and perspective.
The camera must have some means of support, usually provision for mounting it on a tripod.
Zone plate
A zone plate is a device used to focus light. Unlike lenses however, zone plates use diffraction instead of refraction. Created by Augustin-Jean Fresnel, they are sometimes called Fresnel zone plates in his honor. The zone plate's focusing ability is an extension of the Arago spot phenomenon caused by diffraction from an opaque disc.
A zone plate consists of a set of radially symmetric rings, known as Fresnel zones, which alternate between opaque and transparent. Light hitting the zone plate will diffract around the opaque zones. The zones can be spaced so that the diffracted light constructively interferes at the desired focus, creating an image there. Zone plates produce equivalent diffraction patterns no matter whether the central disk is opaque or transparent, as long as the zones alternate in opacity.
A zone plate consists of a set of radially symmetric rings, known as Fresnel zones, which alternate between opaque and transparent. Light hitting the zone plate will diffract around the opaque zones. The zones can be spaced so that the diffracted light constructively interferes at the desired focus, creating an image there. Zone plates produce equivalent diffraction patterns no matter whether the central disk is opaque or transparent, as long as the zones alternate in opacity.
Night photography
Night photography refers to photographs taken outdoors between twilight and dawn. Night photographers generally have a choice between using artificial light or using a long exposure, exposing the scene for seconds or even minutes, in order to give the film enough time to capture a usable image, and to compensate for reciprocity failure. With the progress of high-speed films, higher-sensitivity digital image sensors, wide-aperture lenses, and the ever-greater power of urban lights, night photography is increasingly possible using available light.
Panoramic photography
Panoramic photography is a format of photography that aims to create images with exceptionally wide fields of view, but has also come to refer to any photograph that is cropped to a relatively wide aspect ratio (see Panoramic format) While there is no formal definition for the point at which "wide-angle" leaves off and "panoramic" begins, truly panoramic image are thought to capture a field of view comparable to, or greater than, that of the human eye - about 160° by 75° - and should do so while maintaining detail across the entire picture. The resulting images are panoramic, in that they offer an unobstructed or complete view of an area - often, but not necessarily, taking the form of a wide strip. A panoramic photograph is really defined by whether the image gives the viewer the appearance of a "panorama," regardless of any arbitrary technical definition.
Photo-finishers and manufacturers of Advanced Photo System (APS) cameras also use the word "panoramic" to refer to any print format with a wide aspect ratio, not necessarily photos that encompass a large field of view. In fact, a typical APS camera in its panoramic mode, where its zoom lens is at its shortest focal length of around 24 mm, has a field of view of only 65°, which many photographers would only classify as wide angle, not panoramic. Cameras with an aspect ratio of 2:1 or greater (where the width is 2 times its height) can generally be classified as being "panoramic."
Photo-finishers and manufacturers of Advanced Photo System (APS) cameras also use the word "panoramic" to refer to any print format with a wide aspect ratio, not necessarily photos that encompass a large field of view. In fact, a typical APS camera in its panoramic mode, where its zoom lens is at its shortest focal length of around 24 mm, has a field of view of only 65°, which many photographers would only classify as wide angle, not panoramic. Cameras with an aspect ratio of 2:1 or greater (where the width is 2 times its height) can generally be classified as being "panoramic."
Photogram
A photogram is a photographic image made (without a camera) by placing objects directly onto the surface of a photo-sensitive material such as photographic paper and then exposing it to light. The result is a silhouetted image varying in darkness based on the transparency of the objects used, with areas of the paper that have not received any light appearing light and those that have appearing dark, according to the laws of photosensitivity. The image obtained is hence a negative and the effect is often quite similar to an X-Ray. This method of imaging is perhaps most prominently attributed to Man Ray and his exploration of rayographs. Others who have experimented with the technique include László Moholy-Nagy, Christian Schad (who called them "Schadographs"), Imogen Cunningham and even Pablo Picasso.
Photographic mosaic
In the field of photographic imaging, a photographic mosaic (also known under the term Photomosaic, a portmanteau of photo and mosaic, trademarked by Runaway Technology, Inc.) is a picture (usually a photograph) that has been divided into (usually equal sized) rectangular sections, each of which is replaced with another photograph of appropriate average color. When viewed at low magnifications, the individual pixels appear as the primary image, while close examination reveals that the image is in fact made up of many hundreds or thousands of smaller images. They are a computer created type of montage.
Originally, the term photomosaic referred to compound photographs created by stitching together a series of adjacent pictures of a scene. Space scientists have been assembling mosaics of this kind since at least as early as the Soviet Union space satellite missions to the moon in the late 1950s.
Originally, the term photomosaic referred to compound photographs created by stitching together a series of adjacent pictures of a scene. Space scientists have been assembling mosaics of this kind since at least as early as the Soviet Union space satellite missions to the moon in the late 1950s.
Photographic print toning
In photography, toning is a photographic process carried out on silver-based (black-and-white) photographic prints to change their colour. Some toning processes can improve the chemical stability of the print and allow it to last longer. Other toning processes can make the print less stable.
Many early prints that exist today were toned with sepia toner.
Most toners work by replacing the metallic silver in the emulsion with a silver compound, such as silver sulfide (Ag2S) in the case of sepia toning. The compound may be more stable than metallic silver and may also have a different colour or tone. Different toning processes give different colours to the final print. In some cases, the printer may choose to tone some parts of a print more than others.
Toner also can increase the tonality of a print. This increases the range of visible shades without reducing contrast. Selenium toning is especially strong in this regard.
Many toners are highly toxic. It is extremely important that the chemicals are used in a well ventilated area. Rubber gloves and face protection should be worn when handling them. Some toners are carcinogens.
Many early prints that exist today were toned with sepia toner.
Most toners work by replacing the metallic silver in the emulsion with a silver compound, such as silver sulfide (Ag2S) in the case of sepia toning. The compound may be more stable than metallic silver and may also have a different colour or tone. Different toning processes give different colours to the final print. In some cases, the printer may choose to tone some parts of a print more than others.
Toner also can increase the tonality of a print. This increases the range of visible shades without reducing contrast. Selenium toning is especially strong in this regard.
Many toners are highly toxic. It is extremely important that the chemicals are used in a well ventilated area. Rubber gloves and face protection should be worn when handling them. Some toners are carcinogens.
Push printing
In photography, push printing and push developing refer to a process where a picture is printed as if it were a film speed higher than intended by the film manufacturer. For instance, a photo which is metered one f-stop under can be pushed a stop to compensate either in developing or in printing.
In push developing (also known as push processing), the developer changes the development time or temperature to increase contrast. By leaving the film in the developer longer the highlights increase in silver density. When doing this, the entire roll must be pushed; pushing a roll during developing gives better results than pushing it in printing, but the entire roll must be metered "off" the same amount. That is, if one picture is -1; they must all be -1. Push developing a film cannot be undone.
Photos may also be pushed in printing. This is generally required with an under-exposed 'thin' negative. The paper is exposed less (through aperture or time) but the development time stays the same; as a result, the photo is lightened so that more detail is visible. This process affects the print and not the negative and so can be tried to different degrees. Because an under-exposed negative fails to record shadow detail, pushing a print can lead to large areas of thin shadows lacking in detail. In the darkroom, this is usually managed by 'burning in' the shadows to give them depth if not detail. Other side effects may be that colors are weakened, contrast may be over-emphasized, and considerable grain may be added to the image. Push printing is not suitable for all types of film.
Push printing is sometimes done without the photographer's knowledge or permission, especially on newer automated systems which prompt the developer about potential "problem" photos. In the example to the right, one picture on an ISO 400 roll was pushed four stops.
The image shows two photos of a woman in a car: the top one was metered according to the average light within the full image frame. As a result of the bright light in the background, her face was left in silhouette. The developer pushed the photo four stops to compensate, bringing out the features of the subject's face.
In push developing (also known as push processing), the developer changes the development time or temperature to increase contrast. By leaving the film in the developer longer the highlights increase in silver density. When doing this, the entire roll must be pushed; pushing a roll during developing gives better results than pushing it in printing, but the entire roll must be metered "off" the same amount. That is, if one picture is -1; they must all be -1. Push developing a film cannot be undone.
Photos may also be pushed in printing. This is generally required with an under-exposed 'thin' negative. The paper is exposed less (through aperture or time) but the development time stays the same; as a result, the photo is lightened so that more detail is visible. This process affects the print and not the negative and so can be tried to different degrees. Because an under-exposed negative fails to record shadow detail, pushing a print can lead to large areas of thin shadows lacking in detail. In the darkroom, this is usually managed by 'burning in' the shadows to give them depth if not detail. Other side effects may be that colors are weakened, contrast may be over-emphasized, and considerable grain may be added to the image. Push printing is not suitable for all types of film.
Push printing is sometimes done without the photographer's knowledge or permission, especially on newer automated systems which prompt the developer about potential "problem" photos. In the example to the right, one picture on an ISO 400 roll was pushed four stops.
The image shows two photos of a woman in a car: the top one was metered according to the average light within the full image frame. As a result of the bright light in the background, her face was left in silhouette. The developer pushed the photo four stops to compensate, bringing out the features of the subject's face.
Push processing
Push processing is a term from photography, referring to a development technique that increases the speed of the film being processed.
Push processing involves developing the film for longer, and/or at a higher temperature. This allows larger grains of silver to form in the emulsion, forming a darker negative. This results in a lighter print and hence an increase in the apparent film speed. The opposite of push processing is called pull processing, which decreases the speed of the processed film. It is achieved by developing the film for a shorter time, and/or at a lower temperature.
Push processing is more popular than pull processing as photographers usually want to make a film faster, not slower. As such, the term push processing is sometimes used as a generic term for both push processing and pull processing.
By push processing film, a higher film speed than the manufacturer's indication can be achieved, allowing the film to be used under lighting conditions that would ordinarily be too low for good exposures. However, this comes at the cost of decreased quality: artefacts such as higher contrast, lower resolution, distorted colours, increased grain, etc. are often visible on film that has been push processed. Often, film is push processed to create these artefacts as part of an artistic effect. When a film has been push or pull processed, the resulting speed is called the EI, or exposure index; the film's speed is always the manufacturer's indication. For example, an ISO 200 film could be push processed to EI 400 or pull processed to EI 100.
Push processing involves developing the film for longer, and/or at a higher temperature. This allows larger grains of silver to form in the emulsion, forming a darker negative. This results in a lighter print and hence an increase in the apparent film speed. The opposite of push processing is called pull processing, which decreases the speed of the processed film. It is achieved by developing the film for a shorter time, and/or at a lower temperature.
Push processing is more popular than pull processing as photographers usually want to make a film faster, not slower. As such, the term push processing is sometimes used as a generic term for both push processing and pull processing.
By push processing film, a higher film speed than the manufacturer's indication can be achieved, allowing the film to be used under lighting conditions that would ordinarily be too low for good exposures. However, this comes at the cost of decreased quality: artefacts such as higher contrast, lower resolution, distorted colours, increased grain, etc. are often visible on film that has been push processed. Often, film is push processed to create these artefacts as part of an artistic effect. When a film has been push or pull processed, the resulting speed is called the EI, or exposure index; the film's speed is always the manufacturer's indication. For example, an ISO 200 film could be push processed to EI 400 or pull processed to EI 100.
Rephotography
Rephotography is the act of repeat photography of the same site, with a time lag between the two images; a "then and now" view of a particular area. Some are casual, usually taken from the same view point but without regard to season, lens coverage or framing. Some are very precise and involve a careful study of the original image. The founding work in this style was the Rephotographic Survey project, conceived in 1977 by the project's chief photographer, Mark Klett. This project engaged 120 sites of government survey photographs from the American west first recorded in the 1870's. The resulting book, Second View, The Rephotographic Survey Project, included precise rephotographs of the same locations 100 years later along with an essay by Klett on the methodology and problems encountered with rephotography. Klett revisited these sites a third time for his 2005 book Third View with a new team of photographers including Byron Wolfe, Michael Marshall and Toshi Ueshina.
The accurate rephotographer needs to determine several facts before taking a new image. An important starting point is the choice of the older image. It's usually a good idea to show continuity between the two images by including in the frame a building or other object which is still there in the modern view. Some urban scenes change so much that the original buildings shown have been completely obscured by subsequent skyscrapers, or have been demolished. A "then and now" photograph could be taken but there would be nothing in common to link the two images.
The vantage point from which the original photographer took the view may have disappeared over the years, so the rephotographer has to choose an original view for which the vantage point is still accessible, or arrange to rent equipment to duplicate the original position of the camera.
Since modern cameras have lenses that differ considerably from older lenses, the rephotographer also has to take into account the area that the lens covers, and the depth of field available. Older lenses were softer than their modern equivalents, and usually of a larger aperture, reducing the "wide-angle" feel that modern lenses record.
Through scrutiny of the original image, the rephotographer needs to determine the season and the time of day from observation of the vegetation and the shadows shown in the original view. The best way to do this is to set up a camera at the original viewpoint, at approximately the right season and time, and wait with the original view in hand, until the shadows reach the same positions relative to surrounding objects. If done with extreme accuracy it should be possible to place one image over the other, and see the edges of buildings match exactly. A good example of this type of rephotography can be seen in the McCord Museum of Canadian History's virtual exhibition "Urban Life through Two Lenses." Another is Douglas Levere's project, "New York Changing", has recently been published. Here Levere rephotograped 114 of Berencie Abbott's, "Changing New York" images.
Rephotography is often used by the scientific world to record the effects of erosion over time, or to measure the extent of sand banks in a river, or other time-related phenomena.
The accurate rephotographer needs to determine several facts before taking a new image. An important starting point is the choice of the older image. It's usually a good idea to show continuity between the two images by including in the frame a building or other object which is still there in the modern view. Some urban scenes change so much that the original buildings shown have been completely obscured by subsequent skyscrapers, or have been demolished. A "then and now" photograph could be taken but there would be nothing in common to link the two images.
The vantage point from which the original photographer took the view may have disappeared over the years, so the rephotographer has to choose an original view for which the vantage point is still accessible, or arrange to rent equipment to duplicate the original position of the camera.
Since modern cameras have lenses that differ considerably from older lenses, the rephotographer also has to take into account the area that the lens covers, and the depth of field available. Older lenses were softer than their modern equivalents, and usually of a larger aperture, reducing the "wide-angle" feel that modern lenses record.
Through scrutiny of the original image, the rephotographer needs to determine the season and the time of day from observation of the vegetation and the shadows shown in the original view. The best way to do this is to set up a camera at the original viewpoint, at approximately the right season and time, and wait with the original view in hand, until the shadows reach the same positions relative to surrounding objects. If done with extreme accuracy it should be possible to place one image over the other, and see the edges of buildings match exactly. A good example of this type of rephotography can be seen in the McCord Museum of Canadian History's virtual exhibition "Urban Life through Two Lenses." Another is Douglas Levere's project, "New York Changing", has recently been published. Here Levere rephotograped 114 of Berencie Abbott's, "Changing New York" images.
Rephotography is often used by the scientific world to record the effects of erosion over time, or to measure the extent of sand banks in a river, or other time-related phenomena.
Rollout photography
Rollout photography, a type of peripheral photography, is a process used to create a two dimensional photographic image of a three dimensional object. This process is the photographic equivalent of a cylindrical map projection in cartography. It is used predominantly for the projection of images of cylindrical objects such as vases or ceramic vessels. The objective of this process is to present to the observer a planar representation of the object's characteristics, most notably the illustrations or artwork extant on the outside surfaces of such vessels. This planar representation is captured using photographic imaging techniques.
The Sabattier effect
Initially, the term solarisation was used to describe the effect observed in cases of extreme overexposure of the negative in the camera. The effect generated in the dark room was then called pseudo-solarisation. This fine distinction is not made in the jargon of contemporary photography.
The effect was first described in print by H. de la Blanchere in 1859 in L’Art du Photographe. It was described again in 1860 by L.M. Rutherford and C.A. Seely, separately, in successive issues of The American Journal of Photography, and in the same year by Count Schouwaloff in the French publication Cosmos. The phenomenon should have been christened the Blanchere Effect, for it was not described by Sabatier until later in 1860 in Cosmos, and another paper published in 1862 in the Bulletin de Societe Francaise de Photographie.
The effect was usually caused by inadvertent severe over-exposure or occasionally by accidentally exposing an exposed plate or film to light before processing. Artist Man Ray perfected the technique which was accidentally discovered in his darkroom by his assistant Lee Miller. It is evident from publications in the 19th century that this phenomenon was invented very many times by many photographers as it tends to occur whenever a light is switched on inadvertently in the darkroom whilst a film or print is being developed.
In modern film photography, this effect can be emulated for artistic effect by briefly exposing the film to actinic light during chemical development. However, because of the speed of modern films, the effect is much more commonly seen in printing.
In solarisation, not only are parts of the image reversed in tone but a thin line is generated around areas of contrasting tone, called a Mackie line. If a film is treated the line is light, which produces a dark line in the print; when the print itself is processed it produces a white or light line around areas of high contrast. It is therefore always possible to determine whether a film or print has been used to produce the solarisation.
The effect was first described in print by H. de la Blanchere in 1859 in L’Art du Photographe. It was described again in 1860 by L.M. Rutherford and C.A. Seely, separately, in successive issues of The American Journal of Photography, and in the same year by Count Schouwaloff in the French publication Cosmos. The phenomenon should have been christened the Blanchere Effect, for it was not described by Sabatier until later in 1860 in Cosmos, and another paper published in 1862 in the Bulletin de Societe Francaise de Photographie.
The effect was usually caused by inadvertent severe over-exposure or occasionally by accidentally exposing an exposed plate or film to light before processing. Artist Man Ray perfected the technique which was accidentally discovered in his darkroom by his assistant Lee Miller. It is evident from publications in the 19th century that this phenomenon was invented very many times by many photographers as it tends to occur whenever a light is switched on inadvertently in the darkroom whilst a film or print is being developed.
In modern film photography, this effect can be emulated for artistic effect by briefly exposing the film to actinic light during chemical development. However, because of the speed of modern films, the effect is much more commonly seen in printing.
In solarisation, not only are parts of the image reversed in tone but a thin line is generated around areas of contrasting tone, called a Mackie line. If a film is treated the line is light, which produces a dark line in the print; when the print itself is processed it produces a white or light line around areas of high contrast. It is therefore always possible to determine whether a film or print has been used to produce the solarisation.
Stereoscopy
Stereoscopy, stereoscopic imaging or 3-D (three-dimensional) imaging is any technique capable of recording three-dimensional visual information or creating the illusion of depth in an image. The illusion of depth in a photograph, movie, or other two-dimensional image is created by presenting a slightly different image to each eye. Many 3D displays use this method to convey images. It was first invented by Sir Charles Wheatstone in 1838 . Stereoscopy is used in photogrammetry and also for entertainment through the production of stereograms. Stereoscopy is useful in viewing images rendered from large multi-dimensional data sets such as are produced by experimental data. Modern industrial three dimensional photography may use 3D scanners to detect and record 3 dimensional information. The three-dimensional depth information can be reconstructed from two images using a computer by corresponding the pixels in the left and right images. Solving the Correspondence problem in the field of Computer Vision aims to create meaningful depth information from two images.
Traditional stereoscopic photography consists of creating a 3-D illusion starting from a pair of 2-D images. The easiest way to create depth perception in the brain is to provide to the eyes of the viewer two different images, representing two perspectives of the same object, with a minor deviation similar to the perspectives that both eyes naturally receive in binocular vision. If eyestrain and distortion are to be avoided, each of the two 2-D images preferably should be presented to each eye of the viewer so that any object at infinite distance seen by the viewer should be perceived by that eye while it is oriented straight ahead, the viewer's eyes being neither crossed nor diverging. When the picture contains no object at infinite distance, such as a horizon or a cloud, the pictures should be spaced correspondingly closer together.
Traditional stereoscopic photography consists of creating a 3-D illusion starting from a pair of 2-D images. The easiest way to create depth perception in the brain is to provide to the eyes of the viewer two different images, representing two perspectives of the same object, with a minor deviation similar to the perspectives that both eyes naturally receive in binocular vision. If eyestrain and distortion are to be avoided, each of the two 2-D images preferably should be presented to each eye of the viewer so that any object at infinite distance seen by the viewer should be perceived by that eye while it is oriented straight ahead, the viewer's eyes being neither crossed nor diverging. When the picture contains no object at infinite distance, such as a horizon or a cloud, the pictures should be spaced correspondingly closer together.
Sun printing
Sun printing can mean two different processes.
Most commonly it is a photographic process in which the final print is produced by conventional lithographic printing processes.
The process uses a film of gelatine spread on a flat and rigid surface. This is coated with a dilute solution of Potassium dichromate and dried in low light conditions. A translucent positive of the final print is secured in tight contact with the treated gelatine layer and exposed to bright sunlight for a period of up to 30 minutes. During this time the sunlight and the Potassium dichromate tan the gelatine exposed to light.
The gelatine layer is developed by washing in warm water so that the untanned gelatine is washed away. The plate is dried revealing the required design as a relief print. The surface can be inked and printed in a hand press to produce any number of identical prints of the original subject.
The other process involves the "printing-out" of a negative in contact with a sheet of black and white photographic paper and exposing it to the sun. Depending on type of paper the exposure will vary from a few minutes to a couple of hours. The paper will produce a developed image in brownish to purple hues, again depending on the paper used. The paper is then fixed and washed as in normal processing. Prints can later be toned to achieve different tones.
Most commonly it is a photographic process in which the final print is produced by conventional lithographic printing processes.
The process uses a film of gelatine spread on a flat and rigid surface. This is coated with a dilute solution of Potassium dichromate and dried in low light conditions. A translucent positive of the final print is secured in tight contact with the treated gelatine layer and exposed to bright sunlight for a period of up to 30 minutes. During this time the sunlight and the Potassium dichromate tan the gelatine exposed to light.
The gelatine layer is developed by washing in warm water so that the untanned gelatine is washed away. The plate is dried revealing the required design as a relief print. The surface can be inked and printed in a hand press to produce any number of identical prints of the original subject.
The other process involves the "printing-out" of a negative in contact with a sheet of black and white photographic paper and exposing it to the sun. Depending on type of paper the exposure will vary from a few minutes to a couple of hours. The paper will produce a developed image in brownish to purple hues, again depending on the paper used. The paper is then fixed and washed as in normal processing. Prints can later be toned to achieve different tones.
Ultraviolet photography
Ultraviolet photography is a photographic process of recording images by using light from the ultraviolet (UV) spectrum only.
Light which is visible to the human eye covers the spectral region from about 400 to 750 nanometers. This is the radiation spectrum used in normal photography. The band of radiation that extends from about 1 nm to 400 nm is known as ultraviolet radiation. UV spectrographers divide this range into three bands:
* near UV (380–200 nm wavelength; abbrev. NUV)
* far UV (or vacuum UV) (200–10 nm; abbrev. FUV or VUV)
* extreme UV (1–31 nm; abbrev. EUV or XUV).
Only near UV is of interest for UV photography, for several reasons. Ordinary air is opaque to wavelengths below about 200 nm, and lens glass is opaque below about 180nm. UV photographers subdivide the near UV into:
* Long wave UV that extends from 320 to 400 nm,
* Medium wave UV that extends from 280 to 320 nm,
* Short wave UV that extends from 200 to 280 nm.
(These terms should not be confused with the parts of the radio spectrum with similar names.)
There are two ways to use UV radiation to take photographs - reflected ultraviolet and ultraviolet fluorescence photography. Reflected ultraviolet photography finds practical use in medicine, dermatology, criminology and theatrical applications. Sunlight is the most available free UV radiation source, but the quality and quantity of the radiation depends on atmospheric conditions. A bright and dry day is much richer in UV radiation and is preferable to a cloudy or rainy day. Another suitable source is electronic flash which can be used efficiently in combination with an aluminium reflector. Some flash units have a special UV absorbing glass over the flash tube, which must be removed before the exposure. Special UV lamps known as "black light" fluorescence tubes are used for long wave ultraviolet photography. Most modern UV sources are based on a mercury arc sealed in a glass tube. By coating the tube internally with a suitable phosphor, it becomes an effective long wave UV source.
Light which is visible to the human eye covers the spectral region from about 400 to 750 nanometers. This is the radiation spectrum used in normal photography. The band of radiation that extends from about 1 nm to 400 nm is known as ultraviolet radiation. UV spectrographers divide this range into three bands:
* near UV (380–200 nm wavelength; abbrev. NUV)
* far UV (or vacuum UV) (200–10 nm; abbrev. FUV or VUV)
* extreme UV (1–31 nm; abbrev. EUV or XUV).
Only near UV is of interest for UV photography, for several reasons. Ordinary air is opaque to wavelengths below about 200 nm, and lens glass is opaque below about 180nm. UV photographers subdivide the near UV into:
* Long wave UV that extends from 320 to 400 nm,
* Medium wave UV that extends from 280 to 320 nm,
* Short wave UV that extends from 200 to 280 nm.
(These terms should not be confused with the parts of the radio spectrum with similar names.)
There are two ways to use UV radiation to take photographs - reflected ultraviolet and ultraviolet fluorescence photography. Reflected ultraviolet photography finds practical use in medicine, dermatology, criminology and theatrical applications. Sunlight is the most available free UV radiation source, but the quality and quantity of the radiation depends on atmospheric conditions. A bright and dry day is much richer in UV radiation and is preferable to a cloudy or rainy day. Another suitable source is electronic flash which can be used efficiently in combination with an aluminium reflector. Some flash units have a special UV absorbing glass over the flash tube, which must be removed before the exposure. Special UV lamps known as "black light" fluorescence tubes are used for long wave ultraviolet photography. Most modern UV sources are based on a mercury arc sealed in a glass tube. By coating the tube internally with a suitable phosphor, it becomes an effective long wave UV source.
Tilted plane focus
Focus is relative to spatial depth. Selective focus in photography is usually associated with depth of focus. A pinhole generates an image of ‘infinite’ relative focus from a point just outside the opening out to infinity. Lenses focus more selectively so that for objects near the lens the distance between lens and sensor or film is increased, and is shortened for more distant objects to a point beyond which all is in focus. In telephoto lenses this point may be tens or hundreds of metres from the camera. Wide-angle lenses distinguish differences in depth only up to a short distance beyond which all is in focus.
Time-lapse
Time-lapse photography is a cinematography technique whereby each film frame is captured at a rate much slower than it will be played back. When replayed at normal speed, time appears to be moving faster and thus lapsing. Time-lapse photography can be considered to be the opposite of high speed photography.
Processes that would normally appear subtle to the human eye, such as motion in the sky, become very pronounced. Time-lapse is the extreme version of the cinematography technique of undercranking, and can be considered a borderline form of stop motion animation.
Processes that would normally appear subtle to the human eye, such as motion in the sky, become very pronounced. Time-lapse is the extreme version of the cinematography technique of undercranking, and can be considered a borderline form of stop motion animation.
Zoom burst
Zoom burst is a photographic technique, attainable with zoom lenses with a manual zoom ring. The term is sometimes attributed to Peter Bargh in his article Creative zoom bursts technique. Using the technique involves zooming while the shutter is open with a relatively slow shutter speed, generally below 1/60th of a second. For this reason low light or small apertures are required. It is also possible to achieve a similar effect with either computer software like Adobe Photoshop (after the photo has been shot) or a photographic filter. In these cases the shutter speed can be as fast as necessary
Photographs taken with this technique are characterized by blurred streaks emenating from the center of the photograph. The effect is nearly identical to a motion blur image in which the camera is traveling towards the subject. For this reason the zoom burst is typically used to create an impression of motion towards the subject.
Photographs taken with this technique are characterized by blurred streaks emenating from the center of the photograph. The effect is nearly identical to a motion blur image in which the camera is traveling towards the subject. For this reason the zoom burst is typically used to create an impression of motion towards the subject.
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