Key Light or Fill Light? Photography Vocab Terms Defined
Posted on February 20 2014
Knowing the terms in a certain field is always useful to help enrich your understanding and communication about a subject. In photography, many of the terms used today in digital photography transferred over from film photography practices. When using programs like Adobe Photoshop, these companies still carry over the same terms originally used in the wet darkroom to the digital darkroom. Here is a brief introduction of terms:
Ambient - ambient light is the available or surrounding light
Aperture - the amount of light being let in through the lens (lens opening) see f-stop
ASA- a film speed rating similar to an ISO rating
Bracket - to over and then under expose from the indicated camera settings. This technique provides several different exposures from which one may choose the best negative for printing.
Burn in - to darken a specific area of a print by giving it additional printing exposure
Contrast - the difference between light and dark values. An image that is only pure black and white with no shades of gray is said to have high contrast. Images with many shades of gray and no black or white are low contrast
Density - the amount (or thickness) of silver on the film or paper. Over exposed negatives are dense (thick) with silver. When maximum density is reached the negative or print is as black as possible. This maximum density is called D-MAX.
Depth of field - the distance range between the nearest and farthest points that are in acceptably sharp focus. Depth of field is altered by 1. Aperture size 2. Length of lens 3. Distance to subject
Dodge - to lighten an area of a print by shading it during part of the printing exposure
Emulsion - a light sensitive coating applied to photographic films or papers. It consists of silver halide crystals and other chemicals suspended in gelatin
Fill light - a source of illumination that lightens shadows cast by the main light and thereby reduces the contrast in a photograph
F-stop - also referred to as f- number. A number indicating the size of the lens opening. It is determined by dividing the focal length of a lens by the diameter of the aperture when measured in millimeters.
Grain - the clumping of silver in the negative that gives the image a "sandy" or "speckled" appearance. Films with low ISO numbers will have less clumping and therefore finer grain.
ISO - (international standards organization) a numerical rating that describes the sensitivity of a film to light. The ISO rating doubles as the sensitivity of the film doubles. Rating combines the ASA (once standard in US) and the DIN (European standard) an example would be ISO 100/20*
Main Light – also known as key light. The strongest and most effective light sourced used.
Panning - to follow the motion of a moving object with the camera this will cause the object to look sharp and the background blurred
Reciprocity - reciprocity law - the relationship between length of exposure and aperture size. When equivalent exposures are required, an increase in one will be balanced by a decrease in the other. For example, doubling aperture size will be balanced exactly by halving the exposure time. The reciprocity law fails with very short or very long exposures.
Stop down - to use a smaller lens opening