A Glossary of Photographic Terms: O - P

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Some of the ready resources: Nikon - Terms, SLRs, lenses || Canon - A & T series SLRs , FD Lenses || Minolta -XK/XD11 || Pentax - LX || Olympus - OM1/OM2 series, Zuiko Lenses || Contax - RTS Series | Hasselblad - Bodies, older lenses | Rollei - bodies

Off-The-Film Metering

A meter which determines exposure by reading light reflected from the film during picture-taking or a way of metering meters light reflects off film plane during exposure. First pioneered by Olympus on its famous OM2n, which is real time metering for normal exposure and flash exposures. Most flash mode for modern cameras are with OTF flash mode now.

OTF Test (Optical Transfer Functions)

Evaluates lens performance in terms of resolving power, contrast rendition and abberrations. Most believes the test is the only way to determine how good a lens is in the lab - at least the tester (esp photo magazines) does.

Ortho (Orthochromatic)

Denotes film sensitive to blue and green light.


A condition in which too much light reaches the film, producing a dense negative or a very bright/light print or slide.


Phase Alternation Line. System for minimising hue errors in colour transmission used in the EU.

Pan Format

"Pan" format - one of the three selectable Advanced Photo System print formats; a 1:3 aspect ratio that produces prints of 3.5 x 10.5 inches or up to 4.5 x 11.5 inches; suitable for panoramic shots and tall or wide subjects.

Pan (Panchromatic)

Designation of films that record all colors in tones of about the same relative brightness as the human eye sees in the original scene, sensitive to all visible wave-lengths.


Moving the camera so that the image of a moving object remains in the same relative position in the viewfinder as you take a picture. The eventual effect creates a strong sense of movement.


A broad view, usually scenic.


With a lens-shutter camera, parallax is the difference between what the viewfinder sees and what the camera records, especially at close distances. This is caused by the separation between the viewfinder and the picture-taking lens. There is no parallax with single-lens-reflex cameras because when you look through the viewfinder, you are viewing the subject through the picture-taking lens.


Personal Computer.

PC Cords

The purpose of sync cords is to allow the camera to control the flash, so the flash fires at the correct time. Other common names for electrical cords to connect flash to camera are PC cord, sync cord and synch cord. One type of electrical connector on camera bodies is called a PC socket, whence the name, PC cord. Sync and synch are both intended to be abbreviations of the word synchronization.

PC Terminal/PC socket

Some older flash units may not have a hot shoe onthe flash unit and would need cable connection to fire timely. It is a threaded collar surrounding the center electrical part of the socket. Some flash cords have a connector that makes electrical contact with the center part of the socket and is held securely in place by a threaded ring which screws into the outer part of the socket on the camera body. It is another alternative way to sync the electronic flash on the camera. Some of the modern autofocus cameras have omiited this feature on the body. It can also be used to activate another flash unit via sync cord in a multiple flash setup. PC sockets and common PC cords fit together by pushing the connector on the cord into the socket on the camera. It remains connected only because of friction.

PC (photographic 1)

Prontor/Compur. The clip on socket of the flash mode terminal.

PC (photographic 2)

Perspective control. Also known as tilt or shift lenses. Lenses that allow for correction of linear distortion resulting from high or low camera angle. Most are with gear or sliding mechanism and most require manual metering.


Regularly and accurately spaced holes punched throughout the length of film for still cameras. Basically the perforation function as a guide for precision registration of film and also provide mechanical movement from frame to frame.


The rendition of apparent space in a flat photograph, i.e., how far the foreground and background appear to be separated from each other; determined by only one factor: the camera-to-subject distance; if objects appear in their normal size relations, the perspective is considered "normal"; if the foreground objects are much larger than the ones in the background, the perspective is considered "exaggerated"; when there is little difference in size between foreground and background, we say the perspective looks "compressed."

Photo File Index Print

A basic system feature that makes ordering reprints and enlargements easy; the small print shows a positive, "thumbnail"-sized version of every picture on an Advanced Photo System film roll; accompanies all prints and negatives returned in the sealed film cassette by the photofinisher; each thumbnail picture is numbered on the index print to match negative frames inside the cassette.

Photolamp (3400K).

Photographic lamp giving more light than a normal lamp of the same wattage, at the expense of filament life. Often referred to by the trade mark Photo Hood. Are used with type A colour films.

Picture angle

The angle of coverage of a lens usually measured across the diagonal of the picture frame; varies with focal length: the longer the focal length, the narrower the picture angle; the shorter the focal length, the wider the picture angle. Telephoto ratio Is derived by dividing the distance from the front vertex of a lense to the front vertex by the focal length. The smaller the telephoto ratio, the smaller the total length of the lens.

Pincushion Distortion

The opposite of barrel distortion; straight lines are bowed in toward the middle to resemble the sides of a pincushion; present in smal amounts in some telephoto and telephoto-zoom lenses.

Photofinisher Service Certification

Program developed by the System Developing Companies to give special recognition to photofinishers and retailers who provide the minimum Advanced Photo System feature set; an identifying logo signals to consumers which photofinishers and retailers provide all of the mandatory benefits of the system.


The process of taking photographs of minute objects using a camera and a microscope; not to be confused with "microphotography," the process of making minute photographs of large objects.


Level surface. Used in photography chiefly in respect to focal plane, an imaginary level surface perpendicular to the lens axis in which the lens is intended to form an image. When the camera is loaded the focal plane is occupied by the film surface.

Polarising Screen (Filter)

A filter that transmits light travelling in one plane while absorbing light travelling in other planes. When placed on a camera lens or on light sources, it can eliminate undesirable reflections from a subject such as water, glass, or other objects with shiny surfaces. This filter also darkens blue sky.

Polarized light.

Light waves vibrating in one plane only as opposed to the multi-directional vibrations of normal rays. Natural effect produced by some reflecting surfaces, such as glass, water, polished wood, etc., but can also be simulated by placing a special screen in front of the light source. The transmission of polarized light is restrained by using a screen at an angle to the plane of polarization.


The opposite of a negative, an image with the same tonal relationships as those in the original scenes-for example, a finished print or a slide.

Preset iris.

Diaphragm with two setting rings or one ring that can be moved to two positions. One is click-stopped, but does not affect the iris, the other moves freely and alters the aperture. The required aperture is preset on the first ring, and the iris closed down with the second just before exposure.


A positive picture, usually on paper, and usually produced from a negative.

Printing Frame

A device used for contact printing that holds a negative against the photographic paper. The paper is exposed by light from an external light source.


(See Burning-in)


Developing, fixing, and washing exposed photographic film or paper to produce either a negative image or a positive image.

Program Exposure

An exposure mode on an automatic or autofocus camera that automatically sets both the aperture and the shutter speed for proper exposure.

Programmed Auto:

Camera sets both shutter speed and aperture for correct exposure.

Push Processing

Increasing the development time of a film to increase its effective speed (raising the ISO number for initial exposure ) for low-light situations; forced development.

A Glossary of Photographic Terms Menu - O - P

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