Most of the names of camera parts and other technical terms relating to camera functions are well known. But in case some are not quite clear, here are a few quick definitions.

Accessory Shoe:
A clip fitted to the top of many cameras to hold special viewfinders, additional rangefinders, flash guns, or other accessories.

The size of the actual tens opening, expressed as a fraction of the focal length. The aperture defines the light passing power of the lens, and can be varied to control exposure.

Kodak patented system for writing notes on to film backing paper which subsequently appeared on the negative.

Automatic Exposure
Cameras that measure the amount of light available, and automatically make adjustments to their settings to achieve a proper exposure.

Barrel Lens
A large format lens not mounted in a leaf shutter.

Backing Paper:
Strip of paper along the back of a roll film which protects the film against the light and permits loading of the spool in daylight. The rear of the paper carries black numbers on a (usually) yellow background which are observed through a window in the camera back, and show how far the film must be wound on from one exposure to the next.

Hollow flexible lightproof 'box' of pleated thin leather. Used to minimize weight and size in folding cameras.

Bellows Misfold
When the above mentioned bellows are folded up incorrectly, and a crease appears other than where a crease should be.

Between-lens Shutter (diaphragm shutter):
A number of pivoted overlapping blades placed between the elements of a lens. Variable spring tension, air escapement or clockwork mechanisms control the period during which the blades swing open for exposure.

A slanting surface or bevel on the edge surround of a lens. Also a groove or flange designed to hold a lable or information plate that may surround a lens. The frame around a CRT or LCD screen.

Box Camera
The simplest of cameras, shaped as their name suggests, like a box. They can be found made out of wood, cardboard, plastic or metal, many times with leather or cloth covering.

Wear of the finish down to the base metal, which is usually brass. Most frequently seen on black paint finish and on nickel plating, but can be found on chrome subject to heavy wear, or in some cases, really poor chrome plating.

Brilliant Frame Finder:
Viewfinder which shows a brilliant luminous frame reflected into the view outlining the subject field.

Bromide Paper:
Fast, light-sensitive paper used for making enlargements. Must be handled under a photographic safelight.

Cable Release:
A wire sheathed in a hollow flexible cable with a threaded nipple at one end and a plunger at the other. Screws into the camera shutter or a suitable socket and is used to release the shutter without actually touching the camera.

Negative-on-paper process devised by W. H. Fox Talbot in 1841.

Capping Plate:
A form of auxiliary shutter, found especially in certain reflex cameras, to protect tile film against the light while the main shutter is open during focusing, viewing, or changing lenses.

Cartridge Film:
Early name for paper-backed celluloid roll film.

Small metal canister, with light-trapped slot for holding 35min still film.

Changing box:
Holder loaded in a darkroom with several plates with a facility for changing them sequentially. The change between plates was made in normal light.

Cleaning Marks
Marks in the lens coating due to grit on the surface of the lens during cleaning with lens paper or cloth. Always blow off your lens first. Some softer coatings are more prone to this than others.

Cloudy Lens
A lens that if you hold it up to the light, does not appear clear. May be caused by a fungus, or a breakdown in the cement in the lens sets.

Coated Lens
A lens that has had the glass covered with a layer of "coating" that reduces flare, particularly from stray light from outside the angle of view. Improves contrast.

Nitrocellulose dissolved in ether. Forms a thin, flexible, transparent layer on evaporation of the solvent.

Colour Correction:
A colour corrected lens will bring most colours to the same focus and thus avoids loss of sharpness due to colour fringes in the image. Specially important in colour photography. The better the lens, the more perfect is usually the degree of colour correction.

Contact Print:
A positive photograph made by passing light through a negative on to sensitive paper, pressed in contact with it, in a printing frame.

Coupled rangefinder:
A rangefinder mechanically or optically linked to the camera lens.

When the glue that binds two cemented elements breaks apart. You will see hunreds of little cracks inside your lens.

Cross front:
Facility for moving the lens sideways from the midpoint of the plate or film. Used for precise control of perspective or, as a rising front, when the camera is used on its side.

Cut film:
See Sheet film.

First publicly announced photographic process. The silver surface of a copper supporting plate was sensitized with iodine, developed over mercury vapour and fixed in strong salt solution, hypo or sodium cyanide solution.

Darkroom Refills:
Suitably cut and prepared lengths of un-spooled 35 mm film which can be loaded into a cassette in the dark.

Another name for a plateholder.

Delayed Action:
Mechanism built into some shutters which delays opening of the shutter for several seconds after release. Useful for self portraits, etc. Also known as self timer.

Detective Camera:
Name originally used for a disguised or hidden camera around the early 1880s. The name was subsequently applied to almost any hand-held camera.

Depth Of Field Indicator:
Scale or other device to show the limits of the depth of field at any camera setting and aperture.

Chemical used to reveal the otherwise invisible or latent image on a photosensitive material after exposure.

An aperture, of varying size, placed within or before a lens to control exposure.

Direct Positive:
A photograph made directly without first obtaining a negative. Examples are daguerreotypes and tintypes.

Double Darkslide (DDS):
Holder for two plates placed back to back.

Double Exposure Lock:
Interlinking between shutter release and film transport and shutter release, preventing a second exposure until after the film has been advanced.

Drop Bed Camera
A camera whose front door drops down to provide the rail for the lens to run out on.

Dry Plate:
Sheet of glass with a light-sensitive surface, usually silver bromide in gelatin, which could be stored and used perfectly dry.

Electronic Flash:
Light source consisting of a high voltage discharge through a special tube which gives a fast brilliant flash and can be used many hundreds of times.

When used in the context of my descriptions, it means that a name or identifying number has been etched into the metal or plastic of an item. This always reduces the value to a collector, and to a lessor extent, to a user. How much this lowers the price is dependant on the location, size and neatness with which the evgraving was done. Light professional engraving on the baseplateis much less objectional than large, crudely engraved characters that look like they were engraved with a nail on the front of the camera.

A positive print, larger than the original negative made by projecting an enlarged image of it on to sensitized paper.

Apparatus for projecting an enlarged image of a negative on to sensitized paper.

Exposure Meter:
Instrument which measures the strength of the light, usually by means of a photoelectric cell, and indicates the exposure required. Often built into the camera.

Exposure Value:
Exposure setting on certain shutters with coupled aperture and speed controls. A given exposure value always represents the same exposure, irrespective of the aperture speed combination chosen.

Extension Tubes:
Tubes or spacing rings interposed between the lens and camera body on cameras with interchangeable lenses to increase the lens film distance for close-up work.

"f/" Stop
Considered by many to be an almost mystical number. Actually a formula relating the width of the aperture to the focal length of the lens. It is a ratio expressed, for example, as 1:2.8. Most often this gets shortened down to f/2.8. See also aperture and focal length.

Failing Front:
See Rising front.

See Tintype.

Field Camera:
Wooden folding plate camera, of relatively light construction, intended for indoor or outdoor use on a tripod.

Film Counter:
Counting mechanism, especially on 35 mm cameras, to show the number of frames exposed. Advances with each operation of the film transport.

Film Indicator:
Memory aid fitted to many cameras to show the type and, or speed of the film loaded.

Film Lock:
Locking mechanism coupled to film transport which arrests the latter when sufficient film has been advanced for the next exposure. May be freed by the shutter release or independent film release.

Film Pack:
Twelve sheets of flexible, celluloid film, each attached to a strip of paper, held in a light-tight flat pack. After exposure the sheet was drawn to the rear of the pack by pulling its paper tab.

Film Pack Adaptor (FPA):
Metal or wood holder for a film pack which was attached to the camera in place of the plateholder.

Finder Frame:
Viewfinder consisting of an open front frame and rear sight.

Finder Multiple:
Viewfinder showing the field of view for lenses of several focal lengths. May be accessory finder, or sometimes built into the camera.

Finder Optical:
Viewfinder based on t lie inverted Galilean shows the view on a reduced scale and takes up little space.

Chemical for permanently removing the light sensitivity of photographic materials. Usually hypo (sodium thiosulphate) although sodium or potassium cyanide was commonly used for fixing daguerreotypes.

Flash Bulb:
Light source producing an intense flash for a fraction of a second by the burning of metal wire in oxygen inside a glass bulb. Ignited electrically, and can be synchronized with the shutter.

Flash Socket:
Outlet on shutter to take flash cable connected to contacts built into the shutter which close the firing circuit of the flash unit.

Flash Synchronization:
Timing of the closing of the flash contact inside the shutter so as to make the peak brightness of the flash coincide with the maximum shutter opening at instantaneous shutter speeds.

Flatness Of Field:
Ability of the lens to form its image on t lie flat area of the negative, yielding even sharpness all over the negative. Requires suitable lens design.

Focusing Front Cell:
Adjustment for setting the lens for different subject distances by increasing the separation between the front component and the rest of the lens.

Focal Length:
The nearest distance a lens can be from the film when focused on a distant object. The longer the focal length, the larger the image scale.

Focal Plane Shutter:
Cloth or metal band running close to the surface of the sensitive material. Exposure time is controlled by altering the width of gap in the band or its traverse speed.

Adjustment of the distance of a lens to the film or plate surface to give a sharp image.

Focusing Helical:
One of several methods of setting the distance by moving the whole lens forward and back, in this case in a coarse screw mounting.

Focusing Hood:
Rigid or folding shield surrounding a focusing screen to protect it from extraneous light.

Focusing Screen:
Sheet of ground glass, mounted on top of the body in reflex cameras, on which the lens projects an image closely similar to the image formed on the film. Can serve as a check on sharpness and field of view.

Folding Camera:
A camera, usually of bellows form, which can be folded for storage and carrying.

The growth of fungus inside a lens. It can be seen as many thin lines, like spiderwebs, or looking like little snowflakes. Sometimes lenses can be disassembled, and the fungus removed. But other times, it will etch the glass, and this cannot be fixed.

Gaslight Paper:
Light-sensitive paper used for making contact prints. Slow enough to handle in subdued gaslight without fogging.

Ground glass screen:
See Focusing screen.

Hand camera:
Term given to cameras designed to be held in the hand, rather than on a tripod, when taking pictures.

A camera whose format is 18x24 on 35mm film. This is the original format of 35mm film as movie stock.

Hazy Lens
See Cloudy Lens.

Instant Return Mirror
A SLR whose mirror returns to the viewing position immediately after the exposure has been made.

Interchangeable Lenses:
Provision for using lenses of different focal lengths on one camera, thus giving sonic control over the scale of the image formed. Either the whole lens may be interchangeable (by means of a screw or bayonet mount), or only the front unit (convertible lenses).

Iris Diaphragm:
Set of pivoted leaves built into the lens which by means of an external control can increase or decrease the effective lens opening or aperture (q.v.). Oil some cameras the operation of the iris may be semi automatic or automatic, as when the lens must be fully open for focusing on a ground glass screen, but close down to a pre selected aperture for exposure.

Large Format
Generally, any camera that uses cut film 4x5 or bigger.

Leaf Shutter
This style of shutter uses a bunch of little shutter blades that open and close kinda like the iris of a lens. They are located between the lens elements.

Lens:The principle photographic forms are:
Petzval portrait lens.. combination of lens elements giving a reasonably sharp image at around f4 over a narrow angle of view.
Achromat (meniscus): thin lenses of crown and flint glass cemented together to form a single meniscus lens. Used at fl 1 and smaller apertures.
Rapid rectilinear.. pair of achromatic meniscus lenses mounted in a tube with a central diaphragm. Used at f8 and below. Gives reasonably sharp pictures; definition improves at smaller stops. Anastigmat: combination of lens elements giving sharp images, essentially free of all distortions. Made with relatively large maximum apertures, originally around f6.3 in the 1890s, widening to fl.5 by 1939.

Lens Hood:
Black cone or tube which fits over the front of the lens and shields it against stray light from outside the subject area.

Light Meter:
Instrument for measuring light levels and indicating the exposure required.

Line Frame Finder:
See Brilliant Frame Finder.

Magazine Camera:
Camera, usually box-shaped, containing six or twelve plates which were exposed and changed sequentially.

Interchangeable film holder in certain cameras permitting the changing of films in the middle of the roll or cassette in full daylight, and in a matter of seconds.

Medium Format
Generally any rollfilm camera larger than 35mm.

Miniature Cameras:
Term originally applied to cameras taking a negative smaller than 6 square inches (39 sq cm) in area. In time came to be used for cameras taking 35mm still film.

A photographic image where the light parts of the subject are recorded as dark tones and vice versa.

Panoramic Camera
A camera that produces a short wide photo. Some use extremely wide angle lenses with a narrow film. Others use a normal focal length lens that swings, exposing the film in a sweep on a curved flm plane.

Difference in the view seen by the finder of the camera and recorded on the film. Arises from the fact that usually the optical axis of the finder does not coincide with that of the lens. Can be compensated in various ways, but is worrisome only at nearer subject distances.

Suitably shaped prism arrangement built into certain single lens reflex cameras above the ground glass screen to permit observation of the screen image at eye level and to show an upright and right-way round picture.

Pressure Plate:
Sprung plate of metal, plastic, or even glass to press the film against the film track to keep it accurately positioned at the correct distance behind the lens.

Originally metal, later a sheet of glass supporting a photosensitive layer.

A slim light-tight box, with a removable cover for holding and exposing photographic plates.

A photographic image where the subject's light and dark tones are correctly recorded.

A photographic positive, usually on paper.

Press Camera
A style of camera popular with the press from the middle 1910's until the late 1940's. The most popular was the Speed Graphic. These were drop bed cameras ranging in size from 2-1/4 x 3-1/4 up to 5 x 7, although 4 x 5 tended to become the most standard. They were fitted with rangefinders for quick focus, and usually had a large, side mounted flash unit.

Short for pentaprism, it refers to a finder which provides and upright, non-mirror image for viewing through a lens and mirror.

Optical instrument for measuring distances; may be coupled to the lens so that adjustment of the rangefinder automatically sets the lens to the correct distance.

Rapid Winding Lever:
Modern design of film transport control in the form of a lever, one or. two swings of which advance the film (and sometimes tension the shutter as well). Much faster to work than a winding knob.

A lens that renders straight lines straight.

Reflex Cameras:
Form of camera in which an image is focused and composed on a ground glass screen up to the moment of exposure. The image in the single-lens reflex is reflected on to the screen by a mirror which moves completely out of the light path an instant before the exposure is made. A separate viewing lens, linked to the taking lens, forms the image in the twin-lens reflex.

Ability of the lens to distinguish fine image detail. Can be measured in various ways, and is often expressed as lines/mm. The final resolution of an image in a picture also depends on the film and other conditions.

A lens design for wide angle lenses allowing them to be physically longer than their focal length. Made necessary by the SLR camera design, where room is needed behind the rear element of the lens for the swinging mirror.

Reversing Button Or Lever:
Device on miniature cameras to disengage the film transport drive and to permit an exposed film to be rewound into its cassette (q.v.).

Rewind Knob:
(sometimes a crank) connected to a shaft which engages the centre spool of a 35 mm. film cassette. Used to rewind the film into the cassette.

Rising or Falling Front:
A rising front is a facility for lifting the lens vertically above the midpoint of the negative axis. Useful for recording tall subjects, such as buildings, without the converging verticals which result from tilting the camera. A failing front, where the lens is lowered with respect to the negative, is used in a similar way to record subjects below camera level without distortion.

Roller Blind Shutter:
An opaque blind, with a fixed gap, travelling from one roller to another close to the lens. Exposure time is controlled by altering the traverse speed.

Roll Film:
Flexible film giving several exposures on a continuous length of material. Originally unbacked and loaded in a darkroom, from 1895 more usually with an opaque numbered paper backing for daylight loading.

Film that comes in rolls, rather than in sheets.

Roll-Film Holder:
Lightproof box for holding and winding roll film. Attached to the back of a plate camera in place of a darkslide.

Self Erecting Lens Panel:
Provision, by an arrangement of struts and levers, for automatically bringing the lens into the taking position in a folding camera when the camera is opened. Nowadays a standard feature of such cameras.

Whent he glue that binds two elements of a lens or prism together fails, the two elements create what appears like oil upon water, kind of feddish and mirror-like, usually appearing at the edges.

Sheet Film (cut film):
Stiff sheets of flexible transparent material, originally celluloid, with a photosensitive coating, used in place of glass plates.

Self Timer:
See Delayed Action.

Device for allowing light to pass through a lens for a predetermined length of time.

Shutter, Diaphragm:
Shutter mechanism consisting of a set of leaves opening from the centre outwards, and mounted between or just behind the lens elements. Diaphragm shutters evenly illuminate the whole negative area, are easy to synchronize for flash, but limit lens interchangeability.

Shutter, Focal Plane:
Shutter mechanism consisting of two blinds forming a variable slit and moving past the film just in front of it. Focal plane shutters expose the film in strips, permit easy lens changing, are capable of the highest shutter speeds, but are not easy to synchronize for flash.

Shutter Speed:
Exposure time in fraction of a second at any given shutter setting. The higher the shutter speed, the shorter the exposure time. High shutter speeds are necessary to get sharp pictures of fast moving subjects.

Single Metal Slide (SMS):
A holder for one plate. Usually made from black enamelled sheet steel.

Slow Speed Dial
Some early focal plane shutters had two shutter speed dials, one that controled the gap between the curtains (fast speeds) and one that controled a delay in releasing the second curtain (slow speeds). On many cameras, this dial was located on the front of the camera, on others, it was a second ring under the fast speed dial.

Slow Speeds Stick
Slow speeds on both the focal plane shutters, as well as on leaf shutters, are timed by a spring which release is slowed by the drag of some of the gears.

SLR (Single Lens Reflex)
A camera in which the lens you view through is the same lens used to take the photo. A mirror directs the image up onto a focusing screen the exact same distance from the lens as the film is. As the exposure is made, the mirror swings out of the way, and then the shutter fires.

Early name for a tripod or camera support.

Viewer for stereoscopic photographs.

Stereoscopic Camera:
Camera for taking a pair of photographs from positions a few inches apart. When viewed in a stereoscope the resulting pictures give an illusion of depth.

See Diaphragm.

In 1914 , Eastman Kodak company introduced the autographic feature on their cameras. This enable a written message to be inscribed on the negative, by means of "writing" with a metal stylus on the paper back of the film through a flap in the back of the camera. A carbon layer between the backing paper and the film was cleared by pressure from the stylus, the flap faced to the light, and the "message" was recored on the neg. Ingenious, and worked well till by about 1930, films had become too sensitive and the flap let light in and the feature was no longer practicable.
(The feature was rarely used however, attested to by the fact that you never see an autographically marked megative or print today. Also the little pen, attached to the camera in varios ways through the years, usually got lost anyway).

Camera using film material narrower than the standard miniature (35 mm.) film. Many subminiatures are little larger than a matchbox.

Swing or tilting front and back:
Facility for altering the angle of the lens board or sensitive material with respect to the camera base. Used for controlling image sharpness and perspective.

Telephoto Lens:
Lens giving a larger image than a lens of standard focal length at about the same distance from lens to film or plate.

Tintype (ferrotype):
Blackened tinplate bearing a positive collodion image. Used by cheap while-you-wait photographers.

TLR (Twin Lens Reflex)
A style of camera using two matched lenses, usually on above the other, that share a common focusing device. Most often the focusing lens will be faster than the taking lens to aid in easier and more precise focus, while the taking lens will be much sharper.

Three-legged camera support.

Tripod Bush:
Fitting in the bottom of a camera, enabling it to be screwed on top of a tripod for time exposures, etc.

Uncoupled Rangefinder
A rangefinder that is not coupled to the taking lens, the focus must be taken off of a scale on the rangefinder, and transfered to the focus on the lens. A real pain, and not very accurate. See also rangefinder.

View Camera
A camera with movements designed to allow the photographer control over perspective, distortion and the plane of focus. Usually large format, although one company marketed a 35mm model.

Equipment for showing the limits of the view which the camera will record. (Also See Finder.)

Viewing screen:
See Focusing screen.

Waterhouse stops:
A diaphragm made from a strip of brass, with a round hole cut in it, which was placed in a slot cut in the lens mount. Came in a series of f numbers.

Wet collodion:
See Wet plate.

Wet plate (wet collodion plate):
Glass plate coated on one side with a layer of collodion carrying light-sensitive chemicals. It had to be exposed whilst still wet; when dry it lost its sensitivity.

Wet Plate Camera
A camera designed to use the very first glass plates, that had to be coated immediately prior to use, and exposed while still wet. They are usually identifed by heavy staining, and a trough for the chemical to run off on while in the camera.

Further additions to the above are welcome, please email me at john@cooperj.com

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