Photography Glossary - Teacher's Lounge - Freestyle Photographic Supplies

Ever wonder what terms like SLR or TTL mean, but were too embarassed to ask? You are not alone! Browse through our Glossary, and learn things you never knew you never knew.

a | b | c | d | e | f | g | h | i | j | k | l | m | n | o | p | q | r | s | t | u | v | w | x | y | z

Accelerators	The higher the pH of a developer, the faster development occurs. Buffer systems, such as sodium borate or carbonate, are primarily used to raise the pH because they are able to maintain it at a certain value throughout development. The use of a strong alkali such as sodium hydroxide ensures fast development but decreases the useful life of a developer, as strong alkalis tend to oxidize in the presence of air. The choice of alkali is generally dependant on the desired developer activity level and the developing agents used. The pH of most developers is between 7.5 and 14.

Acutance	An objective measure of the distinctness of a line in an image.

Agitation	The primary function of agitation is to keep photographic solutions in motion during processing to guarantee uniformity of action. The type and amount of agitation used in development can have a significant effect on the developed image.

Albumen print	Albumen printing paper was introduced by Louis-Desire Blanquart-Evrard in communication with the Academie des Sciences, Paris, on 27 May 1850, and it remained in general use until about 1859. It could be bought partly prepared, i.e. coated with a thin film of white egg and was then sensitized with silver nitrate solution by the photographer. Toning with chloride of gold checked fading and produced sepia effect, avoiding the unattractive reddening to which the paper was prone.

Ambrotype	The ambrotype process was patented in the USA by James Ambrose Cutting in 1854. The images obtained were known as collodion negative ion front of a black background to produce a positive image.

Aperture	Aperture refers to the size of the opening in the lens that determines the amount of light falling onto the film or sensor. The size of the opening is controlled by an adjustable diaphragm of overlapping blades similar to the pupils of our eyes. Aperture affects exposure and depth of field.

Aperture Priority	In "Aperture Priority" mode, the camera allows you to select the aperture over the available range and have the camera calculate the best shutter speed to expose the image correctly. This is important if you want to control depth of field or for special effects.

Archival	A subjective term used to describe an image that lasts a suitable amount of time before it arts to degrade or fade. As of yet, there is no commonly accepted dividing line between non-archival and archival. As a point of reference, a well-fixed fiber based, silver gelatin (black and white) print has the archival stability of around 100-150 years when stored safely. A properly made platinum print will last at least twice as long. A carbon print will last substantially longer than a platinum print. Toning is one way of increasing the life of a silver gelatin print. Selenium, gold and sepia toners chemically bond their metal molecule to the silver halide, preventing harmful pollutants from bonding instead. The side effect, which is sometimes specifically sought out, can be a perceptible color shift in the print. In the digital world, a print made using pigment inks onto acid-free, 100% cotton, lignen-free paper can last as long as a silver gelatin print. Archival stability is a term used to describe how long a print or painting will last before it starts to visibly degrade.

Auto Bracketing	Bracketing is a technique used to take a series of images of the same scene at a variety of different exposures that "bracket" the metered exposure (or manual exposure). "Auto" simply means the camera will automatically take these exposures as a burst of 2, 3 or 5 frames with exposure settings of anything between 0.3 and 2.0 EV difference. This can be useful if you're not sure exactly how the shot will turn out or are worried that the scene has a dynamic range which is wider than the camera can capture. On a digital camera this can also be used to combine under- and overexposed images together to produce an image with more dynamic range than the camera can capture. When setting up for bracketing you can usually select the number of frames to be taken (typically 2, 3 or 5), the exposure setting and the order in which to take the shots (eg. 0,-,+ or -,0,+ etc.). It is important to note that the values are exposure compensation values.

Auto Focus	A system found on some cameras that perform an electronic analysis of the distance from the camera to a selected subject and an automated response from the lens focusing system to that distance. It is usually activated by a partial depression of the shutter release.

Autochrome	The brand name of the first commercially marketed photographic color process. Introduced in 1907 by the French inventors and manufacturers, Auguste and Lois Lumiere, it was used until the early 1930s. In the autochrome process, starch grains dyed in the three additive primary colors (green, red and blue) were dusted onto a glass plate, flattened under pressure and coated with panchromatic emulsion. The colored grains acted as filters, allowing some colors to be registered on the panchromatic film. After exposure, the films was developed as a black and white negative, and then treated chemically to produce a colored positive. The image appeared to be in full color transmitted onto a screen or seen against the light. The network of starch grains in all autochrome ensured that the images looked grainy, like pointillist paintings.