Glossary of Camera Terms
This glossary of camera and photographic terms is intended to give visitors some reference to terms used in the product descriptions on this site. As such, it is not a comprehensive resource, but will continue to be expanded as new items are added to the catalog. In all cases, we have provided a link back to the original source where more detailed information is available on any given subject.
Alternative Process
The term alternative process refers to any non-traditional, or non-commercial photographic printing process. Currently the standard analog photographic printing process is the gelatin silver process, and standard digital processes include the pigment print, and digital laser exposures on traditional color photographic paper.
Alternative processes are often called historical, or non-silver processes. Most of these processes were invented over 100 years ago and were used by early photographers.
Many contemporary photographers are revisiting alternative processes and applying new technologies (the digital negative) and practices to these techniques.
— Courtesy of Alternative process, Wikipedia.org
Anastigmat
An anastigmat or anastigmatic lens is a photographic lens completely corrected for the three main optical aberrations: spherical aberration, coma, and astigmatism. Early lenses often included the word Anastigmat in their name to advertise this new feature (Doppel-Anastigmat, Voigtländer Anastigmat Skopar, Wollensak Velostigmat, etc.). The first Anastigmat was designed by Paul Rudolph for the German firm Carl Zeiss AG in 1890 and marketed as the Protar.
— Courtesy of Anastigmat, Wikipedia.org
Aperture
In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture of an optical system is the opening that determines the cone angle of a bundle of rays that come to a focus in the image plane. The aperture determines how collimatedthe admitted rays are, which is of great importance for the appearance at the image plane. If an aperture is narrow, then highly collimated rays are admitted, resulting in a sharp focus at the image plane. If an aperture is wide, then uncollimated rays are admitted, resulting in a sharp focus only for rays with a certain focal length. This means that a wide aperture results in an image that is sharp around what the lens is focusing on and blurred otherwise. The aperture also determines how many of the incoming rays are actually admitted and thus how much light reaches the image plane (the narrower the aperture, the darker the image for a given exposure time).
— Courtesy of Aperture, Wikipedia.org
Architectural Photography
Architectural photography is the photographing of buildings and similar structures that are both aesthetically pleasing and accurate representations of their subjects. Architectural photographers, are usually skilled in the use of specialized techniques and equipment.
— Courtesy of Architectural photography, Wikipedia.org
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Bellows
In photography, a bellows is the pleated expandable part of a camera, usually a large ormedium format camera, to allow the lens to be moved with respect to the focal plane for focusing. Bellows are also used on enlargers. The bellows provides a flexible, dark extension between the film plane and the lens. In some cameras, the photographer can change the angle of the film plate with respect to the optical axis of the lens, providing alterations of perspective distortion and of the object plane of focus.
Two kinds of bellows are commonly used on cameras; bag bellows are normally used with a lens of short focal length, and accordion bellows with a much longer range of extension. For large format cameras, “double extension” refers to bellows that extend to a length equal to about twice the focal length of a standard lens, e.g. 300 mm for the 4×5 inch format. “Triple extension” for the same format indicates bellows extension of 450 to 500 mm.
Bellows allow movements that can be used to correct distortion in a photograph and to avoid converging or diverging verticals. Use of a bellows-based camera can ensure that parallel elements in a scene remain parallel in the final photograph.
— Courtesy of Bellows (photography), Wikipedia.org
Box Camera
The box camera is mechanically simple, the most common form is a cardboard or plastic box with a lens in one end and film at the other. The lenses are often single element designs meniscus fixed focus lens, or in better quality box cameras a doublet lens with minimal (if any) possible adjustments to the aperture or shutter speeds. Because of the inability to adjust focus, the small lens aperture and the low sensitivity of the sensitive materials available, these cameras work best in brightly lit daylit scenes when the subject is within the hyperfocal distance for the lens and of subjects that move little during the exposure -- snapshots. During the box cameras heyday, box cameras with photographic flash, shutter and aperture adjustment were introduced, allowing indoor photos.
— Courtesy of Box camera, Wikipedia.org
Camera Obscura
The camera obscura (Latin; camera for "vaulted chamber/room", obscura for "dark", together "darkened chamber/room"; plural: camera obscuras or camerae obscurae) is an optical device that projects an image of its surroundings on a screen. It is used in drawing and for entertainment, and was one of the inventions that led to photography and thecamera. The device consists of a box or room with a hole in one side. Light from an external scene passes through the hole and strikes a surface inside, where it is reproduced, rotated 180 degrees (thus upside-down), but with color and perspective preserved. The image can be projected onto paper, and can then be traced to produce a highly accurate representation.
— Courtesy of Camera obscura, Wikipedia.org
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Collodion
Collodion. The vehicle used in wet-plate processes for holding the haloid salts necessary for the formation of the sensitive film. It is prepared by dissolving pyroxyline (q.v.) in a mixture of equal parts of alcohol and ether, and it is a transparent glutinous liquid, which, when poured upon any surface, leaves, by the evaporation of the solvents, a highly transparent and structureless film of pyroxyline. Methylated alcohol and methylated ether may be, and are, largely used on account of their cheapness. A special kind of collodion, called enamel or leather collodion, is sometimes used for enamelling prints (q.v.).
— Wall's "Dictionary of Photography", F. J. Mortimer & A.L.M. Sowerby, 15th Edition
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Color Photography
Color photography is photography that uses media capable of reproducing colors, which are traditionally produced chemically during the photographic processing phase. By contrast, black-and-white (monochrome) photography records only a single channel ofluminance (brightness) and uses media capable only of showing shades of gray.
In color photography, light-sensitive chemicals or electronic sensors record color information at the time of exposure. This is usually done by analyzing the spectrum of colors into three channels of information, one dominated by red, another by green and the third by blue, in imitation of the way the normal human eye senses color. The recorded information is then used to reproduce the original colors by mixing various proportions of red, green and blue light (RGB color, used by video displays, digital projectors and some historical photographic processes), or by using dyes or pigments to remove various proportions of the red, green and blue which are present in white light (CMY color, used for prints on paper and transparencies on film).
Monochrome images which have been "colorized" by tinting selected areas by hand or mechanically or with the aid of a computer are "colored photographs," not "color photographs." Their colors are not dependent on the actual colors of the objects photographed and may be very inaccurate or completely imaginary.
— Courtesy of Color photography, Wikipedia.org
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Contact Print
A contact print is a photographic image produced from film; sometimes from a filmnegative, and sometimes from a film positive. The defining characteristic of a contact print is that the photographic result is made by exposing through the film negative or positive, onto a light sensitive material that is pressed tightly to the film.
— Courtesy of Contact print, Wikipedia.org
"There were a few reasons why I moved from a 4×5 camera to an 8×10 one, but the main reason was simple – contact prints. I think contact prints are the most pure and fulfilling way to translate a photograph from your mind to the negative and then finally to the paper print. There’s no cropping, enlarging, or hiding anything. The frame of your ground glass, and the border of your negative, is exactly what you get in the print."
— Courtesy of Contact Printing – 8×10 Contact Prints, ShawnHoke.com
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Covering Power
The image area that a lens covers that will produce good even exposure and sharpness. This should exceed the film format area to ensure theres no fall off at the edges. Also the covereing power needs to be large if a camera with lens movements is used.
— Courtesy of Covering power, ePHOTOzine.com
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Cyanotype
Cyanotype is a photographic printing process that produces a cyan-blue print. Engineers used the process well into the 20th century as a simple and low-cost process to produce copies of drawings, referred to as blueprints. The process uses two chemicals: ammonium iron(III) citrate and potassium ferricyanide. The English scientist and astronomer Sir John Herschel discovered the procedure in 1842... It was Anna Atkins who brought this to photography. She created a limited series of cyanotype books that documented ferns and other plant life from her extensive seaweed collection... By using this photogram process, Anna Atkins is regarded as the first female photographer.
— Courtesy of Cyanotype, Wikipedia.org
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Depth of Field (DOF)
In optics, particularly as it relates to film and photography, depth of field (DOF) is the distance between the nearest and farthest objects in a scene that appear acceptably sharp in an image. Although a lens can precisely focus at only one distance at a time, the decrease in sharpness is gradual on each side of the focused distance, so that within the DOF, the unsharpness is imperceptible under normal viewing conditions.
— Courtesy of Depth of field, Wikipedia.org
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Film Plane
A film plane is the area inside any camera or image taking device with a lens and film or digital sensor. The film plane varies in distance from the lens focal point in each manufacturer. Thus each lens used has to be chosen carefully to assure that the image from the lens is focused on the exact place where the individual frame of film or digital sensor is positioned during exposure, the film plane is the location in which the lens creates the focused image which must be exactly upon the light-sensitive material. It is sometimes marked on a camera body with the 'Φ' symbol where the vertical bar represents the exact location.
— Courtesy of Film plane, Wikipedia.org
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Focal Length
The focal length of an optical system is a measure of how strongly the system converges or diverges light. For an optical system in air, it is the distance over which initiallycollimated rays are brought to a focus. A system with a shorter focal length has greater optical power than one with a long focal length; that is, it bends the rays more strongly, bringing them to a focus in a shorter distance.
In most photography and all telescopy, where the subject is essentially infinitely far away, longer focal length (lower optical power) leads to higher magnification and a narrower angle of view; conversely, shorter focal length or higher optical power is associated with a wider angle of view. On the other hand, in applications such as microscopy in which magnification is achieved by bringing the object close to the lens, a shorter focal length (higher optical power) leads to higher magnification because the subject can be brought closer to the center of projection.
— Courtesy of Focal length, Wikipedia.org
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Focal-Plane Shutter
In camera design, a focal-plane shutter (FPS) is a type of photographic shutter that is positioned immediately in front of the focal plane of the camera, that is, right in front of thephotographic film or image sensor.
Most sports photography in the early 20th century was done with Graflex and similar cameras with a cloth focal plane shutter. To produce shutter speeds fast enough to stop rapid motion, they used a narrow slit that exposed different parts of the film at different times. To set the shutter speed, the photographer wound the shutter up to one of a series of tensions with a key, and selected the slit width with another control. A table on the side of the box gave the shutter speed for each combination.
— Courtesy of Focal-plane shutter, Wikipedia.org
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Focusing Screen
A focusing screen is a flat translucent material, either a ground glass or fresnel lens, found in a system camera that allows the user of the camera to preview the framed image in a viewfinder. Often, focusing screens are available in variants with different etched markings for various purposes. For instance, "overall matte" focusing screens with no etchings are a popular choice for astrophotography and other low-light situations.
— Courtesy of Focusing screen, Wikipedia.org
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Fresnel Screen
The Fresnel lens which we use in large-format photography is a converging lens in the form of a thin plastic panel with a series of concentric stepped grooves or rings.
Depending on the direction of the basis they will generate enlarging or diminuating effects. The fresnel screen is placed over the groundglass and brightens up the corners of the groundglass image. Their strength of diffusion facilitates evaluation and accurate focusing especially for short focal lengths. Furthermore accurate exposure determination is made possible through the equal distribution of light.
— Courtesy of Fresnel screens, LotusViewCamera.at
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Graflok Back [c. 1949-1951 and later]
The "Graflok Back" is a desirable, relatively late enhancement to the Graphic line of camera. The Graflok has a removable focus panel, a Fresnel screen, and and features locks to hold various filmbacks.
The Graflok back is the standard for 4x5" view cameras today, and appears on some 2x3" cameras as well. The Graflok back accepts sheet film holders, "Grafmatic" 4x5 sheet film magazines, 120 roll film adaptors, Polaroid backs, the Kodak ReadyLoad and FujiQuickLoad backs, and the now-obsolete film pack.
Graflok backs became standard on all sizes (except 5x7) of Graphics by about 1951, but made their first appearance on the 2-1/4x3-1/4 miniature Graphic about a year earlier. A good many earlier cameras, both Anniversary and Pacemaker series cameras have been modified with the Graflok back.
Kodak Ektalite Fresnel screens became standard shortly after Graflex switched to Graflok backs. In a Graflok back, the position of the Fresnel screen is taken into account in the construction of the back, so removing the lens or trading its position with the ground glass will cause focusing errors. The proper position for a fresnel screen on a Graflok back is between the ground glass and the lens. The grooves of the fresnel should be in contact with the frosted surface of the ground glass. The frosted surface of the ground glass should be toward the front of the camera.
A Graphic or Graflex back with a Fresnel screen is a sign of a user-modified camera, and unless the ground glass holder has been modified specifically to alter the plane of focus, the correct position for the screen is between the photographer and the ground glass. Perform focus tests with your camera before undertaking any modifications to determine whether the correct position of a user-added Fresnel screen for Graphic or Graflex backs.
— Courtesy of Graphic Features, Graflex.org
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Ground Glass
In photography, a sheet of ground glass is used for the manual focusing in some still andmotion picture cameras, the ground-glass viewer is inserted in the back of the camera, and the lens opened to its widest aperture. This projects the scene on the ground glass upside down. The photographer focuses and composes using this projected image, sometimes with the aid of a magnifying glass (or loupe). In order to see the image better, a dark cloth is used to block out light, whence came the image of the old-time photographer with his head stuck under a large black cloth.
A ground glass is also used in the reflex finder of an SLR or TLR camera.
— Courtesy of Ground glass, Wikipedia.org
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Large Format (photography)
Large format refers to any imaging format of 4×5 inches (102×127 mm) or larger. Large format is larger than "medium format", the 6×6 cm (2¼×2¼ inch) or 6×9 cm (2¼×3½ inch) size of Hasselblad, Rollei, Kowa, and Pentax cameras (using 120- and 220-roll film), and much larger than the 24×36 mm (~ 1.0x1.5 inch) frame of 35 mm format.
The main advantage of large format, film or digital, is higher resolution. A 4×5 inch image has about 16 times the area, and thus 16× the total resolution, of a 35 mm frame.
In early photography, large format was all there was, and before enlargers were common, it was normal to just make 1:1 contact prints from a 4×5, 5×7, or 8×10-inch negative.
— Courtesy of Large format (photography), Wikipedia.org
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Lens Board
A Lens board (commonly spelled as lensboard) is a photographic part used for securing a lens to the front standard of a large format view camera. The lens board itself is usually flat, square, and made of metal (most commonly Aluminum) or wood and sometimes plastic. The lens board will have a hole of various diameters drilled dead center on the board. A lens board typically varies between 1 and 4 millimeters in thickness. The overall size and shape of the lens board depends on the brand of camera and film format used. Some cameras will use 2 to 4 screws to secure the lens board to the front standard of the view camera, most commonly however, the lens board will be secured by one or more locking levers or tabs to allow tool-less removal of the lens board. The rear surface of a lens board is usually painted matte black to keep light entering the camera through the lens during exposure from reflecting off the surface and interfering with the projected image.
While most lens boards are flat, some are recessed to accommodate wider focal lengthlenses which must be positioned closer to the film plane. A recessed lens board effectively reduces the flange focal distance of a camera.
— Courtesy of Lens board, Wikipedia.org
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Lumenized
The most recent advance in Kodak lenses in the wide application of Lumenizing. ManyKodak lenses now bear a thin, hard coating of magnesium fluoride to reduce surface reflections and consequently flare light and spots. Picture quality is improved in shadow contrast and detail and in shadow color purity of color pictures. Because of the reduced tendency to veiling and spots, the camera has greater freedom of position with regard to the sun or bright lights. (Source: Data Book Kodak Lenses, Rangefinders and Shutters For Revising Kodak Reference Handbook, ©1942, 1945, Second 1946 Printing)
—Courtesy of Kodak Ektars et al, bnphoto.org
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Motor Drive
A motor drive, in the field of photography, is a powered film transport mechanism. Historically, film loading, advancing, and rewinding were all manually driven functions. The desires of professional photographers for more efficient shooting, particularly in sports and wildlife photography, and the desires of amateur and novice photographers for easier to usecameras both drove the development of automatic film transport. Some early developments were made with clockwork drives, but most development in the field has been in the direction of electrically driven transport.
— Courtesy of Motor drive, Wikipedia.org
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Panorama
A panorama (formed from Greek πᾶν "all" + ὅραμα "sight") is any wide-angle view or representation of a physical space, whether in painting, drawing, photography,film/video, or a three-dimensional model.
Panoramic photography soon came to displace painting as the most common method for creating wide views. Not long after the introduction of the Daguerreotype in 1839, photographers began assembling multiple images of a view into a single wide image. In the late 19th century, panoramic cameras using curved film holders employed clockwork drives to scan a line image in an arc to create an image over almost 180 degrees. Digital photography of the late twentieth century greatly simplified this assembly process, which is now known as image stitching.
— Courtesy of Panorama, Wikipedia.org
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Panoramic Photography
Panoramic photography is a technique of photography, using specialized equipment or software, that captures images with elongated fields of view. It is sometimes known as wideformat photography. The term has also been applied to a photograph that is cropped to a relatively wide aspect ratio. While there is no formal division between "wide-angle" and "panoramic" photography, "wide-angle" normally refers to a type of lens, but using this lens type does not necessarily make an image a panorama. An image made with an ultra wide-angle fisheye lens covering the normal film frame of 1:1.33 is not automatically considered to be a panorama. An image showing a field of view approximating, or greater than, that of the human eye – about 160° by 75° – may be termed panoramic. This generally means it has an aspect ratio of 2:1 or larger, the image being at least twice as wide as it is high. The resulting images take the form of a wide strip. Some panoramic images have aspect ratios of 4:1 and sometimes 10:1, covering fields of view of up to 360 degrees. Both the aspect ratio and coverage of field are important factors in defining a true panoramic image.
— Courtesy of Panoramic photography, Wikipedia.org
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Parallax
Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines. The term is derived from the Greek παράλλαξις (parallaxis), meaning "alteration". Nearby objects have a larger parallax than more distant objects when observed from different positions, so parallax can be used to determine distances.
Parallax error can be seen when taking photos with many types of cameras, such as twin-lens reflex cameras and those including viewfinders (such as rangefinder cameras). In such cameras, the eye sees the subject through different optics (the viewfinder, or a second lens) than the one through which the photo is taken. As the viewfinder is often found above the lens of the camera, photos with parallax error are often slightly lower than intended, the classic example being the image of person with his or her head cropped off. This problem is addressed in single-lens reflex cameras, in which the viewfinder sees through the same lens through which the photo is taken (with the aid of a movable mirror), thus avoiding parallax error.
Parallax is also an issue in image stitching, such as for panoramas.
— Courtesy of Perspective (visual), Wikipedia.org
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Perspective (visual)
Perspective, in the context of vision and visual perception, is the way in which objects appear to the eye based on their spatial attributes; or their dimensions and the position of the eye relative to the objects. There are two main meanings of the term: linear perspective and aerial perspective.
— Courtesy of Perspective (visual), Wikipedia.org
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Pictorialism
Pictorialism is an international style and aesthetic movement in photography that thrived from about 1885 to 1915. It began in response to claims that a photograph was nothing more than a simple record of reality, and transformed into a movement to advance the status of all photography as a true art form. For more than three decades painters, photographers and art critics debated opposing artistic philosophies, ultimately culminating in the acquisition of photographs by several major art museums.
— Courtesy of Pictorialism, Wikipedia.org
Platinum Prints
Platinum prints, also called platinotypes, are photographic prints made by a monochromeprinting process that provides the greatest tonal range of any printing method using chemical development.
Platinum prints are made by photographers and favored by collectors because of their tonal range, the surface quality and their permanence. A platinum print provides a broad scale of tones from black to white. The platinum tones range from warm black, to reddish brown, to expanded mid-tone grays that are unobtainable in silver prints.
Unlike the silver print process, platinum lies on the paper surface, while silver lies in a gelatin or albumen emulsion that coats the paper. As a result, since no gelatin emulsion is used, the final platinum image is absolutely matte with a deposit of platinum (and/or palladium, its sister element which is also used in most platinum photographs) absorbed slightly into the paper.
— Courtesy of Platinum print, Wikipedia.org
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Additional References:
Platinum Prints, Photo Archives Boston Spr 2013
The Platinum Print: A Catalyst for Discussion, Taylor Whitney
The Platinum Printing Process, Tillman Crane
Platinum Photographic Printing Process - Formula + Instructions
Portrait Photography
Portrait photography or portraiture is photography of a person or group of people that displays the expression, personality, and mood of the subject. Like other types of portraiture, the focus of the photograph is usually the person's face, although the entire body and the background or context may be included.
— Courtesy of Portrait photography, Wikipedia.org
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Rapid Rectilinear
The Rapid Rectilinear is a lens that is symmetrical about its aperture stop with four elements in two groups. It was introduced by John Henry Dallmeyer in 1866. The symmetry of the design greatly reduces radial distortion, improving on the Petzval lens.
— Courtesy of Rapid Rectilinear, Wikipedia.org
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Scheimpflug Principle
The Scheimpflug principle is a geometric rule that describes the orientation of the plane offocus of an optical system (such as a camera) when the lens plane is not parallel to the image plane. It is commonly applied to the use of camera movements on a view camera. It is also the principle used in corneal pachymetry, the mapping of corneal topography, done prior to refractive eye surgery such as LASIK, and used for early detection ofkeratoconus. The principle is named after Austrian army Captain Theodor Scheimpflug, who used it in devising a systematic method and apparatus for correcting perspectivedistortion in aerial photographs.
— Courtesy of Scheimpflug principle, Wikipedia.org
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The angles of the Scheimpflug principle, using the example of a photographic lens.
Single-Lens Reflex Camera (SLR)
A single-lens reflex (SLR) camera is a camera that typically uses a mirror and prism system (hence "reflex", from the mirror's reflection) that permits the photographer to view through the lens and see exactly what will be captured, contrary to viewfinder cameras where the image could be significantly different from what will be captured.
— Courtesy of Single-lens reflex camera, Wikipedia.org
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Soft Focus
In photography, soft focus is a lens flaw, in which the lens forms images that are blurred due to spherical aberration. A soft focus lens deliberately introduces spherical aberration in order to give the appearance of blurring the image while retaining sharp edges; it is not the same as an out-of-focus image, and the effect cannot be achieved simply by defocusing a sharp lens. Soft focus is also the name of the style of photograph produced by such a lens.
— Courtesy of Soft focus, Wikipedia.org
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Split-Image Rangefinder Prism
In a reflex camera's focusing screen, a Split-Image, sometimes called a split image rangefinder or Split-Prism, is an optical focus-assistance device that displays an image divided in two. When the image is out of focus, the two halves of the image are separated; when in focus, the halves line up to form a single image. The split is often horizontal, but sometimes diagonal. Split-image devices are often combined with microprisms.
— Courtesy of Split-image device, CameraPedia.Wikia.com
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Telephoto
In photography and cinematography, a telephoto lens is a specific type of a long-focus lens in which the physical length of the lens is shorter than the focal length. This is achieved by incorporating a special lens group known as a telephoto group that extends the light path to create a long-focus lens in a much shorter overall design. The angle of viewand other effects of long-focus lenses are the same for telephoto lenses of the same specified focal length. Long-focal-length lenses are often informally referred to as telephoto lenses although this is technically incorrect: a telephoto lens specifically incorporates the telephoto group.
— Courtesy of Telephoto lens, Wikipedia.org
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Through the Viewfinder Photography (TtV)
Through the Viewfinder photography (TtV) is a photographic or videographic technique in which a photograph or video or motion picture film is shot with one camera through theviewfinder of a second camera. The viewfinder thus acts as a kind of lens filter. The most popular method involves using a digital camera as the image taking camera and an intacttwin-lens reflex camera (TLR) or pseudo-TLR as the "viewfinder" camera. TLRs typically have square waist-level viewfinders, with the viewfinder plane at 90 degrees to the image plane. The image in a TLR viewfinder is laterally reversed, i.e. it is a mirror image. Most photographers use a cardboard tube or similar 'contraption' to connect the two cameras. This serves to eliminate stray light and prevent reflections appearing on the viewfinder glass or on the lens of the imaging camera.
Depending on the model of TLR, the resulting image may have an old-fashioned feel to it, often with vignetting, blurred edges, distortion and dust.
— Courtesy of Through the Viewfinder photography, Wikipedia.org
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Twin-lens Reflex Camera (TLR)
A twin-lens reflex camera (TLR) is a type of camera with two objective lenses of the samefocal length. One of the lenses is the photographic objective or "taking lens" (the lens that takes the picture), while the other is used for the viewfinder system, which is usually viewed from above at waist level. 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. Most TLRs use leaf shutters with shutter speeds up to 1/500th sec with a B setting.
— Courtesy of Twin-lens reflex camera, Wikipedia.org
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Vanishing Point
In graphical perspective, a vanishing point is a point in the picture plane π that is the intersection of the projections (or drawings) of a set of parallel lines in space on to the picture plane. When the set of parallels is perpendicular to the picture plane, the construction is known as one-point perspective and their vanishing point corresponds to theoculus or eye point O from which the image should be viewed for correct perspective geometry. Traditional linear drawings use objects with one to three sets of parallels, defining one to three vanishing points.
— Courtesy of Vanishing point, Wikipedia.org
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View Camera
The view camera is a type of camera first developed in the era of the daguerreotype(1840s-'50s) and still in use today, though with many refinements. It comprises a flexiblebellows that forms a light-tight seal between two adjustable standards, one of which holds alens, and the other a viewfinder or a photographic film holder.
— Courtesy of View camera, Wikipedia.org
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Waterhouse Stop
The Waterhouse stop or Waterhouse diaphragm is an interchangeable diaphragm with an aperture (hole) for controlling the entry of light into a camera. A thin piece of metal (the diaphragm) is drilled with a hole (the aperture); a set of these with varying hole sizes makes up a set of Waterhouse stops, corresponding to what today we call f-stops or f-numbers.Photographic lens makers provided slots in lens barrels for the insertion of the chosen stop.
This apparatus was invented by the pioneering 19th century photographer John Waterhouse of Halifax in 1858.
— Courtesy of Waterhouse stop, Wikipedia.org
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