تويت
المرشد خطوة بخطوة للتصوير الفوتوغرافي .. المصطلحات - الحرف / O - P - R/
Glossary
Terms in italics denote useful cross- references to other glossary entries .
/ O /
Opacity The light stopping power of a material . The greater the opacity of a substance , the more light it stops . In photography opacity is expressed as a ratio of the amount of light falling on the surface of the material to the amount of light transmitted by it .
Optical axis Imaginary line passing horizontally through the center of a compound lens system . A light ray passing along this axis would travel in a straight line .
Orthochromatic Emulsion which is sensitive to blue and green light , and insensitive to red .
Overdevelopment The result of exceeding the recommended amount of development . It is caused by prolonged development time . increased development temperature or agitation . It results in increased density and contrast leading to fog and stains .
Overexposure The result of giving a light - sensitive material excessive exposure increases density and reduces contrast .
/ P /
Panchromatic An emulsion which is sensitive to all colors of the visible spectrum , although it does not react in a uniform way .
Panning In still photography , the technique of swinging the camera to follow a moving subject so that , in the final print , the main subject is sharp and the background is blurred .
Panoramic camera Camera with a special type of scanning lens which rotates about its rear nodal point . exposing a long , curved strip of film . It covers a very large field of view .
Parallax The difference in viewpoint between the image seen through a camera's viewfinder and that recorded by its lens . Except in cameras with through - the - lens viewing systems , there is a slight variance between two views . known as parallax error .
Pentaprism Five - sided glass prism , usually fitted to 35 mm cameras , which makes it easier to view the focusing screen image close - up . It presents the image upright and the right way round .
Perspective System of representing three - dimensional objects on a two- dimensional surface to give a realistic impression of depth . Achieved mostly by means of linear perspec- tive , scale , overlapping elements in the subject , and aerial perspective .
Photo - electric cell Light - sensitive device used in exposure meters . There are two main types : a photo- generative cell which produces electricity when light falls on it ; and photo - resistant types which offer resistance to a battery powered circuit according to light received .
Photoflood Bright , over - run . tungsten lamp giving light of 3,400K .
Photogram Pattern or design produced by placing opaque or transparent objects between a light- sensitive emulsion , and the light source . Then processing the photo- graphic material .
Photomicrography Photography of magnified objects by means of a camera attached to a microscope .
Pincushion distortion Lens aberration which causes parallel . straight lines at the edge of the image field to curve toward the optical axis .
Pinhole camera A simple camera which uses a very hole instead of a lens .
Plate camera Camera designed to take glass plates , today usually adapted to take sheet film .
Plates Large format light - sensitive materials where the emulsion is coated on glass . Now almost entirely replaced by sheet film .
Polarized light Rays of light that have been restricted to vibrate in one plane only .
Polarizing filter Colorless filter able to absorb polarized light .
Polaroid camera Camera designed for instant picture photography .
Polaroid film Sheet film designed to give instant pictures
Positive Photographic image ( on paper or film ) in which light and dark correspond to the highlights and shadows of the original subject .
Posterization Technique of using a number of tone - separated negatives printed on to a high contrast material to produce a photograph containing selected areas of flat tone instead of continuous tones .
Primary colors In light , the three primary colors of the spectrum are blue , green , and red . Each comprises about one third of the visible spec- trum and they can be blended to produce white light or any other hue . ( NB In painter's pigments , the primaries are considered be yellow , blue , and red . )
Principal planes Imaginary lines which pass through the nodal points of a lens system .
Print In photography , usually a positive image , which has been coated with a light - sensitive emulsion by the action of light , usually passed through a negative .
Printing - in Technique for giving additional exposure to selected areas when making a print . Other areas are shaded from the light by an opaque mask .
Prism Transparent material , normally glass , with plane , polished surfaces inclined to one another .
Processing General term used to describe the sequence of steps whereby a latent image is converted into a visible , permanent image .
Projection printing Another term for Enlarging .
Projector Equipment used to display enlarged still or moving images on to a screen .
/ R /
Rangefinder A camera focusing system that determines the distance between camera and subject . The subject is viewed simultaneously from two positions a short distance apart . Two images are seen which can be superimposed by adjusting a mirror or similar device . This adjust- ment is usually linked to the focusing movement of the camera lens .
Rapid fixer Fixing solution which uses ammonium thiocyanate or thiosulfate instead of hypo ( sodium thiosulfate ) . Allows greatly reduced fixing time .
Reciprocity failure The loss of sensitivity of photographic emulsion when exposures are very brief ( less than 1 / 10,000 sec ) or very long ( over one second ) .
Reciprocity law States that exposure equals light intensity x the time it is allowed to act .
Red eye effect Effect where the pupils of a subject's eyes appear red in color photographs taken with flash light illumination . Caused when the red layer underlying the retina reflects light into the camera lens because the flash path is too close to the camera lens axis .
Reducer Solution which reduces some of the silver from negatives or prints , lightening the image .
Reflected light reading Exposure reading taken with the exposure meter pointing toward the subject so that it measures the light reflected from subject surfaces .
Reflector Any surface from which light is reflected . Usually a purpose built area of reflective material positioned to reflect from a main light source into the shadow areas of a subject .
Reflex camera Camera with a viewing and focusing system that uses a mirror to reflect the image rays , after they have passed through a lens , on to a focusing screen .
Refraction The change in direction of light rays as they pass obliquely from one transparent medium to another of different density , e.g. from air to glass .
Resin - coated paper Printing paper with a water repellent base . RC papers process faster , need less washing and dry more quickly than regular fiber types .
Resolving power The ability of the eye , a lens , or a photographic emulsion to resolve fine detail .
Reticulation The minute wrinkling of the emulsion surface of film due to extreme changes of temperature , or acidity / alkalinity excess during processing .
Retouching After - treatment of negatives or prints by hand to remove blemishes and / or change tonal values .
Reversal materials Photographic materials specifically designed to be processed direct to give a result matching the image it has received .
Ring flash Electronic flash tube in the form of a ring surrounding the camera lens . Used when shadowless lighting is required .
Rising front Camera fitting that allows the lens to be shifted upward or downward , remaining parallel to the film plane .
Rollfilm 120/620 , 6 x 7ins or 127 format camera film which has an opaque paper backing and is wound on to a metal spool . The backing paper is numbered to indicate frames , and is longer than the film to provide a light - tight wrapping for daylight loading and unloading . Sometimes applied to any camera film loaded in roll form .
Glossary
Terms in italics denote useful cross- references to other glossary entries .
/ O /
Opacity The light stopping power of a material . The greater the opacity of a substance , the more light it stops . In photography opacity is expressed as a ratio of the amount of light falling on the surface of the material to the amount of light transmitted by it .
Optical axis Imaginary line passing horizontally through the center of a compound lens system . A light ray passing along this axis would travel in a straight line .
Orthochromatic Emulsion which is sensitive to blue and green light , and insensitive to red .
Overdevelopment The result of exceeding the recommended amount of development . It is caused by prolonged development time . increased development temperature or agitation . It results in increased density and contrast leading to fog and stains .
Overexposure The result of giving a light - sensitive material excessive exposure increases density and reduces contrast .
/ P /
Panchromatic An emulsion which is sensitive to all colors of the visible spectrum , although it does not react in a uniform way .
Panning In still photography , the technique of swinging the camera to follow a moving subject so that , in the final print , the main subject is sharp and the background is blurred .
Panoramic camera Camera with a special type of scanning lens which rotates about its rear nodal point . exposing a long , curved strip of film . It covers a very large field of view .
Parallax The difference in viewpoint between the image seen through a camera's viewfinder and that recorded by its lens . Except in cameras with through - the - lens viewing systems , there is a slight variance between two views . known as parallax error .
Pentaprism Five - sided glass prism , usually fitted to 35 mm cameras , which makes it easier to view the focusing screen image close - up . It presents the image upright and the right way round .
Perspective System of representing three - dimensional objects on a two- dimensional surface to give a realistic impression of depth . Achieved mostly by means of linear perspec- tive , scale , overlapping elements in the subject , and aerial perspective .
Photo - electric cell Light - sensitive device used in exposure meters . There are two main types : a photo- generative cell which produces electricity when light falls on it ; and photo - resistant types which offer resistance to a battery powered circuit according to light received .
Photoflood Bright , over - run . tungsten lamp giving light of 3,400K .
Photogram Pattern or design produced by placing opaque or transparent objects between a light- sensitive emulsion , and the light source . Then processing the photo- graphic material .
Photomicrography Photography of magnified objects by means of a camera attached to a microscope .
Pincushion distortion Lens aberration which causes parallel . straight lines at the edge of the image field to curve toward the optical axis .
Pinhole camera A simple camera which uses a very hole instead of a lens .
Plate camera Camera designed to take glass plates , today usually adapted to take sheet film .
Plates Large format light - sensitive materials where the emulsion is coated on glass . Now almost entirely replaced by sheet film .
Polarized light Rays of light that have been restricted to vibrate in one plane only .
Polarizing filter Colorless filter able to absorb polarized light .
Polaroid camera Camera designed for instant picture photography .
Polaroid film Sheet film designed to give instant pictures
Positive Photographic image ( on paper or film ) in which light and dark correspond to the highlights and shadows of the original subject .
Posterization Technique of using a number of tone - separated negatives printed on to a high contrast material to produce a photograph containing selected areas of flat tone instead of continuous tones .
Primary colors In light , the three primary colors of the spectrum are blue , green , and red . Each comprises about one third of the visible spec- trum and they can be blended to produce white light or any other hue . ( NB In painter's pigments , the primaries are considered be yellow , blue , and red . )
Principal planes Imaginary lines which pass through the nodal points of a lens system .
Print In photography , usually a positive image , which has been coated with a light - sensitive emulsion by the action of light , usually passed through a negative .
Printing - in Technique for giving additional exposure to selected areas when making a print . Other areas are shaded from the light by an opaque mask .
Prism Transparent material , normally glass , with plane , polished surfaces inclined to one another .
Processing General term used to describe the sequence of steps whereby a latent image is converted into a visible , permanent image .
Projection printing Another term for Enlarging .
Projector Equipment used to display enlarged still or moving images on to a screen .
/ R /
Rangefinder A camera focusing system that determines the distance between camera and subject . The subject is viewed simultaneously from two positions a short distance apart . Two images are seen which can be superimposed by adjusting a mirror or similar device . This adjust- ment is usually linked to the focusing movement of the camera lens .
Rapid fixer Fixing solution which uses ammonium thiocyanate or thiosulfate instead of hypo ( sodium thiosulfate ) . Allows greatly reduced fixing time .
Reciprocity failure The loss of sensitivity of photographic emulsion when exposures are very brief ( less than 1 / 10,000 sec ) or very long ( over one second ) .
Reciprocity law States that exposure equals light intensity x the time it is allowed to act .
Red eye effect Effect where the pupils of a subject's eyes appear red in color photographs taken with flash light illumination . Caused when the red layer underlying the retina reflects light into the camera lens because the flash path is too close to the camera lens axis .
Reducer Solution which reduces some of the silver from negatives or prints , lightening the image .
Reflected light reading Exposure reading taken with the exposure meter pointing toward the subject so that it measures the light reflected from subject surfaces .
Reflector Any surface from which light is reflected . Usually a purpose built area of reflective material positioned to reflect from a main light source into the shadow areas of a subject .
Reflex camera Camera with a viewing and focusing system that uses a mirror to reflect the image rays , after they have passed through a lens , on to a focusing screen .
Refraction The change in direction of light rays as they pass obliquely from one transparent medium to another of different density , e.g. from air to glass .
Resin - coated paper Printing paper with a water repellent base . RC papers process faster , need less washing and dry more quickly than regular fiber types .
Resolving power The ability of the eye , a lens , or a photographic emulsion to resolve fine detail .
Reticulation The minute wrinkling of the emulsion surface of film due to extreme changes of temperature , or acidity / alkalinity excess during processing .
Retouching After - treatment of negatives or prints by hand to remove blemishes and / or change tonal values .
Reversal materials Photographic materials specifically designed to be processed direct to give a result matching the image it has received .
Ring flash Electronic flash tube in the form of a ring surrounding the camera lens . Used when shadowless lighting is required .
Rising front Camera fitting that allows the lens to be shifted upward or downward , remaining parallel to the film plane .
Rollfilm 120/620 , 6 x 7ins or 127 format camera film which has an opaque paper backing and is wound on to a metal spool . The backing paper is numbered to indicate frames , and is longer than the film to provide a light - tight wrapping for daylight loading and unloading . Sometimes applied to any camera film loaded in roll form .
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