Photo Glossary

Here’s a rundown in plain English of the most common terms you’ll hear or read about in the field of photography.

A

  • Ambient Light
  • The natural light in a scene.
  • Aperture
  • The opening in the front of the camera lens through which light passes to expose the film. Aperture size is usually calibrated in f-numbers, the larger the number, the smaller the lens opening, therefore the slower the shutter must be.
  • APS (Advanced Photo System)
  • APS was devised by a group of five manufactures: Canon, Fuji, Kodak, Minolta and Nikon as a 'breakthrough in camera and film technology' and created a new generation of 'point-and-shoot' cameras. Now, with hindsight, regarded as an interim consumer product which just filled a gap until the more innovative compact digital cameras became affordable. The film size is smaller than 35mm.
  • Autofocus
  • When applied to a lens, it is the ability of a lens to focus automatically on an object within its focusing sensors. This system, considered superior to others, is able to achieve very precise focus in the majority of situations, but is dependent on the light sensitivity of the sensor. Active autofocus systems have, by their very nature, limited range.
  • Available Light
  • Existing light surrounding a subject; whether natural or artificial, but not added by the photographer, like with strobes or speedlights.
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B

  • Backlighting
  • Light from behind the subject, and towards the camera lens, so that the subject stands out against the background. This sometimes can produce a silhouette effect.
  • Bracketing
  • The technique of taking a number of pictures of the same subject at different levels of exposure. At half and one stop differences, depending on subject and film type.
  • Burn (or Burn-in)
  • To make an area of a print darker. This is accomplished after the basic exposure by extending the exposure time (or opening the aperture) to allow extra image-forming light to darken areas of the print while holding back the light from the rest of the image (with hands or card etc.); also called printing-in.
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C

  • C41
  • The number given to a Chemical process for developing color negative film. (created by Kodak but adopted universally by every other manufacturer).
  • CCD
  • Charge Coupled Device (CCD). The Digital camera's 'film'; a CCD converts light into a digital photograph of pixels. When a picture is taken the CCD is struck by light coming through the camera's lens; each of the millions of tiny pixels that make up the sensor converts this light into electrons.
  • Clip Test
  • A test to determine accurate development times using a small part of the exposed film as a sample.
  • CMYK
  • A color system based on the four colors used in color printing: Cyan, Magenta, Yellow and BlacK. Can also be a color mode used to define colors in a digital image. All Digital cameras and scanners are RGB devices, a color method based on combinations of the primary colors Red, Green and Blue this is the same as your TV and PC monitor. CMYK is primarily used when preparing digital images that will be printed using the process colors by a printer or publisher on a four color printing press.
  • Compact Flash
  • A common type of digital camera memory card, about the size of a matchbook. There are two types of cards, Type I and Type II. They vary only in their thickness, with Type I being slightly thinner. A Compact Flash memory card can contain either flash memory or a miniature hard drive. The flash memory type is more common.
  • Composite
  • The act of combining two or more images. Today usually accomplished digitally using 'Photoshop'.
  • Compression
  • A digital file is compressed by removing redundant information. Some image file compression methods discard visual information that may degrade image quality.
  • Contact Print
  • A print made from placing the negative in 'contact' with a sheet of photo paper and then exposed to light; the resulting "Contact print" is the same size as the negative and therefore not enlarged.
  • Contrast
  • A subjective judgment of the difference in brightness and density between shadow and highlight areas in an image. Contrast is affected by lighting, lens flare, film type, degree of development, enlarger type and quality of printing.
  • Cross Process
  • To develop a film in the wrong process (e.g.: neg.(C41) film in trannie(E6) chemicals) to obtain a sometimes bizarre color or contrast effect.
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D

  • Density
  • The blackness of an area in a negative or print. Sometimes referred to as contrast.
  • Depth of Field
  • The distance between the nearest and farthest objects that appear in acceptably sharp focus in a photograph. Depth of field depends on the lens aperture, the focal length of the lens, and the distance from the subject.
  • Depth of Focus
  • Very narrow zone on the image side of the lens within which slight variations in the position of the film will make no appreciable difference to the focusing of the image.
  • Developer
  • A Chemical bath which converts exposed silver halides to black metallic silver, so making the latent image on exposed films or photographic papers visible.
  • Dodge (Dodging)
  • 'Local' control of density in photographic printing achieved by shading (using your hands, small pieces of card or various other dodging tools), therefore, holding back the image-forming light from a part of the photo to make that area of the print lighter.
  • DPI (Dots Per Inch)
  • A measurement unit describing the resolution of hardware, such as a computer monitor or digital printer. Although strictly incorrect, it is now often used as the resolution unit for a digital image.
  • Dupe
  • A duplicate of an original. Usually the term is used to describe a duplicate trannie.
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E

  • E6
  • The number given to a Chemical process for developing color transparency film. (created by Kodak but adopted universally by every other manufacturer).
  • Emulsion
  • The light-sensitive material (which is suspended in micro-thin layers of gelatin) that is coated onto different bases to make photographic film, or paper.
  • Existing Light
  • Available light, includes all natural lighting from moonlight to sunshine; and for photographic purposes, existing light is also the light that is already on the scene. Therefore it takes in: room lamps, fluorescent lamps, neon signs, candles, daylight through windows, and artificially illuminated night scenes.
  • Exposure
  • The quantity of light allowed to act on a photographic material; the lens aperture controls intensity or amount of light, and the shutter speed (or the enlarger timer in printing) controls the time.
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F

  • F Stop
  • A number that indicates the size of the lens opening . The common f-numbers on 35mm cameras are f1.4, f2, f2.8, f4, f5.6, f8, f11, f16, and f22. The larger the f-number, the smaller the lens opening, f22 is the smallest in this series. Also called the aperture, they work in conjunction with shutter speeds to indicate exposure settings. The number sequence is printed on the lens barrel, each higher f number halves the exposure of the preceding one. The f-number itself is effectively the number of times the aperture diameter will divide into the lens focal length. For example, f4 aperture diameter is one quarter the focal length (i.e. 25mm aperture diameter in a 100mm focal length lens).
  • File Format
  • File Size
  • The size of an image in digital photography, measured in kilobytes (K), megabytes (MB), or gigabytes (GB). File size is proportional to its pixel dimensions; images with more pixels may produce more detail at a given printed size, but they require more disk space to store and are slower to edit, print and e-mail as an attachment.
  • Film Speed
  • The sensitivity of a film to light, indicated by a number such as ISO 100. The higher the number, the more sensitive or faster the film. (ISO stands for International Standards Organization.) For example, an ISO 100 film requires less light than an ISO 50 film. Each time you double the film speed, half as much light is needed for a correct exposure. Faster films need less light but they produce grainier pictures. Slower films have a finer grain and they produce more contrast. Pictures taken on slower films are sharper in appearance.
  • Fix
  • Chemical process which converts unused light-sensitive silver-halide crystals to a soluble silver complex in both negatives and prints, making the image stable and unalterable in white light. Also referred to as hypo.
  • Fixed Focus
  • A camera where focus is not adjustable. These cameras are set for a typical focusing distance of more than three feet. Usually, everything from three feet to infinity appears in focus.
  • Flare
  • Non-image-forming light scattered by reflections within a lens or enlarger/camera interior which reduces image contrast and detail. Flare can affect film by causing a lowering of image contrast.
  • Flat
  • Too low in contrast. The range in density in a negative or print is too small.
  • Flash Range
  • The distance over which a flash unit can give adequate illumination.
  • Focal Length
  • The distance, in millimeters, between the center of a lens and the plane of focus (film plane). This distance is measured with the lens focused at infinity.
  • Fogging
  • Density produced on a negative, print or transparency by chemical processing or accidental exposure to light. This can be caused by: 1. exposure to non image-forming light (possibly opening the camera back in daylight) 2. too much handling in air during the development process 3. over-developed 4. outdated film or paper 5. storage of film or paper in a hot, humid place.
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G

  • GIF (Graphic Interface)
  • Designed by CompuServe for using images on line. This is a 256 color or 8 bit image.
  • Gigabyte (GB, Gig)
  • A measure of file size and storage capacity. Most consider a kilobyte to be 1,024 bytes, a megabyte to be 1,024 kilobytes, and a gigabyte to be 1,024 megabytes. However, some key standards groups assume a kilobyte to be 1,000 bytes, a megabyte to be 1,000 kilobytes, and a gigabyte to be 1,000 megabytes. Many data storage manufacturers use this latter measurement to define their device sizes, which leads to computers showing less storage capacity on a drive than the specifications suggests.
  • Grayscale
  • An image made up of varying tones of black and white. Grayscale is synonymous with black and white.
  • Grain
  • The sand-like, granular appearance of a negative, print or trannie. Graininess becomes more noticeable with fast films and increased size of enlargement.(Granularity: The amount of grain clumping that has occurred within an emulsion. Also referred to as graininess.)
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H

  • High Resolution (High Res)
  • Refers to a relatively larger number of pixels per inch in a digital image or scan, which yields a large digital file.
  • Hyperfocal Distance
  • The Hyperfocal Distance or point is the nearest point to the camera which is regarded as acceptably sharp when the lens is focused at infinity. So when the lens is focused on the hyperfocal point, depth of field extends from infinity back to a distance halfway between the camera and the hyperfocal point. This method is used in fixed focus viewfinder and 'box' cameras to obtain a photo that would perhaps include both a far away mountain range and a close group of people in acceptable focus.
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I

  • Image Size
  • The dimensions of a digital image, most clearly expressed in its pixel count, horizontally and vertically.
  • Infinity
  • Focusing point at which the lens gives a sharp image of very distant objects, such as the far horizon.
  • ISO
  • The modern speed rating for photographic materials used instead of ASA or DIN*. The scale is identical to ASA (American Standards Association) where the rating is based on an arithmetical progression, using an average gradient system. Therefore ISO 200 film is twice as fast as ISO 100 film but only half as fast as ISO 400 film.
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J

  • JPEG (Joint Photographic Experts Group)
  • The standard image format of most digital cameras. JPEG files have become a standard in digital imaging because the format is able to record a very high quality image while still having a very compact file size. One potential problem with JPEG files is that each time you make a change to a JPEG and save the file, it loses a little bit of quality. For this reason, always keep your original JPEG in a safe location and if you decide to make changes to it save the changes in a separate file. JPEG compressions are more than adequate for high quality printing. In the early days of digital that wasn't always the case; however, the compression algorithms have become very sophisticated and it is nearly impossible to distinguish a JPEG print from a TIFF print with the naked eye.
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K

  • Kilobyte (KB, K)
  • A measure of file size and storage capacity referring to 1,000 or 1,024, 8-bit data units or characters.
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L

  • Large format
  • As the name implies this is the largest of modern film formats (the most popular being 5"x4" & 10"x8"), and they are especially suitable for high quality commercial work.
  • Lens Speed
  • The largest lens opening, e.g. f2 not f16. A fast lens transmits more light and has a larger opening than a slow lens.
  • LED (Light Emitting Diode)
  • An information display method. Usually used for viewfinder displays since it can be seen in the dark.
  • Light Meter
  • A light sensitive device used for evaluating the amount of light in a scene for exposure. There are four types: Incidental meter, reflective meter, flash meter and spot meter
  • Lossy
  • Many file formats use compression to reduce the file size of bitmap images (digital photo). Lossless techniques compress the file without removing image detail or color information; lossy techniques remove detail. JPEG is the most common file format in digital photography but this is a "Lossy" file format. TIFF with LZW(Lemple-Zif-Welch) compression is the most popular lossless file format.
  • Low Resolution (Low Res)
  • An image file that is one megabyte or less in size when opened in an image editing application. Useful for presentation purposes but insufficient for high quality printed reproduction except at small sizes.
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M

  • Macro lens
  • A lens that provides continuous focusing from infinity to extreme life-size 1:1 close-ups. Also used as a copy lens because of its highly corrected design and close-focusing. Macro lenses can also be used at ordinary subject distances
  • Medium format
  • A larger format than the popular 35mm size, which can provide the image quality necessary for commercial reproduction, using 120, 220 or 70mm film. Various sizes can be shot, the most popular are 6cmx6cm, 6cmx4.5cm and 6cmx7cm.
  • Megabyte (MB)
  • A measure of file size and storage capacity referring to between 1,000,000 and 1,048,576, 8-bit data units or characters. One Megabyte is equal to 1024 kilobytes (KB).
  • Megapixel (MP)
  • Digital camera manufacturers measure the resolution of their cameras in megapixels. One megapixel is equal to one million pixels. The megapixel measurement is figured by multiplying the pixel dimensions of a digital image, that number is then divided by one million. For example, an image that is 2000 x 2500 pixels has a total of 5,000,000 pixels, which means that it is a 5 megapixel image.
  • Memory Card
  • In Digital Photography, a Memory Card is a removable device used in digital cameras to store the images captured by the camera. There are several different types of memory cards available including Compact Flash, SmartMedia, and Memory Stick to name a few.
  • Memory Stick
  • A Sony memory card. Like Compact Flash and Smart Media it is a flash memory based storage system for use in digital cameras. For a description of Memory Stick Pro go to MemoryCards.co.uk
  • Metadata
  • Data embedded and stored within a digital image file. It provides information concerning copyright, credit, restrictions, captions, keywords, or other characteristics. There are several forms of image metadata including EXIF which is used by digital camera makers and provides large amounts of photo information including the make & model, date & time, aperture and shutter-speed.
  • Meter
  • An instrument with a light-sensitive cell that measures the light reflected from or falling onto a subject. Some types can also measure Flash light.
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N

  • Negative (Neg)
  • Developed film that contains a reversed image of the original scene (in a color negative the colors are also reversed, and appear as their complementaries.). Light shone through the transparent negative will make a positive (normal) print on photographic paper.
  • Neutral density filter
  • A neutral gray camera filter which is used to reduce the amount of light entering the camera when a slow shutter speed or wide aperture is needed.
  • Noise
  • Noise refers to the graininess of an image. Noise appears as random, grainy speckles throughout an image. Higher ISO settings typically create more noise.
  • Noise Reduction
  • A major picture quality difference between a digital compact and a DSLR is that the compact produces photos with more noise, similar to the 'grain' of a high ISO traditional film. When a high ISO is set the camera has to amplify the signal received from the sensor and this increases background electrical noise. The larger image sensor of the DSLR has bigger photosites therefore more light gathering capacity and a larger signal to noise ratio. To overcome this problem manufacturers have incorporated noise reduction systems into their cameras. These do reduce noise but also introduce a smoothing effect. Creating a 'smearing' mostly revealed in grass, brickwork and any subject with a fine, repetitive pattern.
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O

  • Over exposed
  • A situation in which too much light reaches the film, which produces a dense negative or a very light transparency.
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P

  • Panchromatic
  • Term used to describe 'Black & White' emulsions that are sensitive to all visible colors. Most modern films are panchromatic.
  • Panning
  • Technique for photographing a moving subject. While the shutter is open, the camera is swung following the moving subject. This creates a blurred background, but a sharp subject. The technique works best with slower shutter speeds.
  • Panoramic camera
  • Camera with a special type of scanning lens which rotates. Or a static lens camera with a wide format e.g. 6cm x 17cm.
  • Parallax error
  • The difference between the image seen by the viewing system and that recorded on the film. Problems occur as the subject moves closer to the taking lens when using TLR cameras. Only through-the-lens viewing systems can avoid parallax error.
  • Pentaprism
  • Optical device, found on SLR cameras, which corrects the image (reversed by the lens), allowing eye-level viewing and focusing via the viewfinder.
  • Photoshop
  • Best known and well used Image manipulation computer program (by Adobe Systems); which has gradually entered the photographers vocabulary with words like: 'Photoshoped' meaning retouched or manipulated.
  • Pincushion effect
  • Lens aberration (distortion) causing parallel, straight lines at the edge of the image to curve inwards.
  • Pixel
  • A single picture element of a digital photo. Pixels are arranged horizontally and vertically within an image, and each one is assigned a specific co lour value.
  • Pull (Pulling)
  • Decreasing the development time of a film to slow its effective speed, e.g.50 ISO instead of its recommended 100 ISO.
  • Push (Pushing)
  • Increasing the development time of a film to increase its effective speed, e.g. 200 ISO instead of its recommended 100 ISO.
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Q

  • No Terms

R

  • Rangefinder
  • A device included on many direct vision cameras as an aid in focusing. It assesses subject distance (usually by comparing two images), and displays this information in the viewfinder. This device may be linked directly to the lens focus control, to give a coupled rangefinder.
  • RAM (Random Access Memory)
  • A type of computer memory that can be accessed randomly; that is, any byte of memory can be accessed without touching the preceding bytes. RAM is the most common type of memory found in computers and other devices, such as printers.
  • RAW
  • An unprocessed digital file direct from the camera. Not a 'standard' file format like TIFF or JPEG. Usually the camera manufactures software or 'plug-in' must be used to open a RAW image file. RAW files are usually used to obtain the best theoretical quality from a given camera.
  • Red-eye
  • The red glow from a subject's eyes caused by light from a flash reflecting off the blood vessels behind the retina in the eye. The effect is most common when light levels are low, outdoor at night, or indoor in a dimly-lit room.
  • Resolution
  • Resolution describes the detail an image holds. The number of pixels displayed per inch of printed length in an image, usually measured in dots per inch (dpi) or pixels per inch (ppi) The amount of detail in an image depends on its pixel dimensions, while the image resolution controls how much space the pixels are printed over. You can modify an image's resolution without changing the actual pixel data in the image all you change is the printed size of the image. For more information on what resolution is and how it affects your photography check out Resolution 101.
  • Retouching and Restorations
  • After-treatment carried out on negatives, prints, or digital files to remove blemishes or change tonal values. Retouching and restorations are most commonly carried out by 'Photoshop' rather than by hand.
  • Resample
  • To change the resolution of an image through interpolation. Resampling downwards discards information and resampling upwards creates new information based on adjacent pixels.
  • Reticulation
  • Fine, irregular pattern appearing on the surface of an emulsion which has been subjected to a sudden and severe temperature change during development.
  • Reversal Film
  • Film or paper designed to produce a positive directly from exposure and processing, without the need of a negative.
  • RGB
  • The way that the colors are recorded in Digital imaging. A large percentage of the visible spectrum can be represented by mixing Red, Green and Blue colored light in various proportions and intensities.
  • Roll Film
  • 120 format film which has an paper backing and is supplied wound on an open spool (rather than in a light-tight cassette). Also the less common double length 220. All these films are used in Medium Format cameras. The term should be applied to all camera films in roll form, including 35 mm.
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S

  • Saturation
  • A characteristic of the observation of color. Saturated colors are called vivid, strong, or deep. Desaturated colors are called dull, weak, or washed out.
  • Secure Digital (SD)
  • A small memory card which uses flash memory as a base for storing digital photos.
  • Sepia Tone
  • Solutions called toners are used to change the color of a black and white photographic image. Creating a print that looks like a "dirty" black white, with brown/rust tones.
  • Shutter
  • Blades or a curtain that controls the time during which light reaches the film.
  • Shutter Speed
  • The length of time during which the camera shutter remains open. These speeds are expressed in seconds or fractions of a second ex: 2, 1, 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000, 1/2000, 1/4000, 1/8000. Each speed increment halves the amount of light.
  • Silver Halide
  • Chemical compound of silver with a halogen. Silver bromide is the principal light sensitive constituent of modern photographic emulsions.
  • Slide
  • A photographic trannie (positive) mounted for projection (usually 35mm).
  • SLR (Single Lens Reflex)
  • A Camera in which you view the scene through the same lens that takes the picture thanks to a system of mirrors and prisms. This image is reflected on a mirror and passes through a prism that restores the normal view. Interchangeable lens 35mm cameras are mostly of this type.
  • Smart Media
  • A wafer-thin sized memory card which uses flash memory as a base for storing digital photos.
  • Speed
  • Sensitivity of a photographic emulsion to light. Films are given ISO numbers which denotes its speed. The term is also used to denote the maximum aperture of a lens.
  • Stop down
  • Changing the lens aperture to a smaller opening; for example, from f4 to f5.6. This increases depth of field.
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T

  • Telephoto Lens
  • A telephoto lens has a longer focal length and narrower field of view than a normal lens and enlarges distant subjects. Depth of field decreases as focal length increases. (Telephoto lens construction: this allows a long focal length with short back focus, making for relative compactness).
  • Thumbnail
  • A small version of a photo. Image browsers commonly display thumbnails of photos several or even dozens at a time. In Windows XP's My Pictures, you can view thumbnails of photos in both the Thumbnails and Filmstrip view modes.
  • TIFF (Tagged Image File Format)
  • TIFF is a common file format used in Digital Photography. This high quality file (which is lossless compared with a JPEG) can also contain color management profiles and be color separated.
  • Transparency
  • A positive photographic image on film, usually color but can be B&W, viewed or projected by light shining through the film.
  • Tungsten film
  • Color film balanced for non-daylight sources (usually studio-type tungsten lamps) of 3200 or 3400K.
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U

  • Under exposed
  • Allowing too little light to reach a photosensitive material. Results in a "thin" or light image with negative material and a "muddy" or dark image with reversal material.
  • UV filter
  • Filter which may be used to absorb UV radiation, to reduce its effect.
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V

  • View Finder
  • An optical viewing device for framing and focusing an image in a camera.
  • Vignette
  • Fall-off in illumination at the edges of an image. This can be caused by poor lens design, using a hood not matched to the lens, or using too many filters at the same time. Vignettes are also created deliberately for an artistic effect.
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W

  • White Balance
  • Depending on the lighting conditions, a pure white in a photograph may appear slightly yellow or blue. The white balance control settings on a "Digital Camera" will help to eliminate unwanted color bias by actually controlling the camera's color temperature response. C.C. filters or a specially balanced film must be used when a film camera is utilized under the same lighting conditions.
  • Wide Angle Lens
  • A lens with a focal length less than the diagonal of the film format it's being used for. For 35mm, usually wider than 50mm. For medium format, wider than 90mm.
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X

  • XD Picture Card
  • A very small memory card which uses flash memory as a base for storing digital photos.
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Y

  • No Terms

Z

  • Zone System
  • A system of 'relating exposure readings to tonal values' in picture-taking, development and printing, popularized by the American photographer Ansel Adams.
  • Zoom Lens
  • A Lens which is constructed to allow a continuously variable focal length; in effect, this gives you many lenses of different focal lengths in one unit. (e.g. 80-200 mm).
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