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Glossary & Index

This glossary contains a list of some common photographic terms, along with a short definition and where you can learn more about the term on this web site. N.B. - The links to other pages on this site are not available yet.

Aperture - an iris in the lens which can cut off the outside portions of the lens, rendering them inactive. Aperture values on the aperture ring represent the focal length of the lens divided by the diameter of the aperture.

Aperture Ring - a ring on the lens of some cameras that allows setting of the aperture number.

Backscatter - a phenomenon caused by light from a strobe reflecting back into the camera lens off of small particles in the water between the subject and the lens. This common problem can be minimized with proper strobe positioning and the use of wide angle lenses.

Bracketing - A technique for getting good results when you're not exactly sure of what to do.  Basically, you make your best guess, and go "a little higher, a little lower."  For exposure settings, this usually means estimating shutter, aperture, and strobe power settings, and then shooting one shot there, one at plus one stop of aperture, and one at minus one stop of aperture.  Some people also bracket in strobe power settings.

C-41 - Not a military explosive, but a term that refers to the chemical process for developing print film.  All consumer print film can be processed with process C-41.

Close Focus Wide Angle (CFWA) - A photographic technique that uses wide angle lens and places the subject within 1 to 2 feet of the lens.   Since wide-angle lenses exaggerate perspective, this makes the subject appear much larger than other, more remote, elements in the picture.

Depth of Field - the range of distances from the lens that will be in sharp focus. DOF is determined by the reproduction ratio of the picture and the aperture of the lens. Higher reproduction ratios result in shallower DOF, as do wider aperture seettings. Smaller apertures result in greater DOF.

E-6 - the chemical process for developing most slide film.

Film Speed - a film's sensitivity to light, usually represented in ISO numbers.  Common numbers include 50,64,100,200,400,800, and 1600. The higher the number, the "faster" the film, and the less light it requires for proper exposure.

Focal Length - a number that represents the length of a lens. Longer focal lengths produce greater magnification than shorter focal lengths. "Normal" lenses for 35mm cameras are in the 35mm to 60mm range. Longer than 60mm is considered "telephoto," while shorter than 35 is considered "wide angle." Lenses shorter than 24mm are often considered "extreme wide angle."

Guide Number - a number that represents the strength of a strobe. The guide number is used in the guide number equation to allow the photographer to select a combination of aperture and distance that will result in a proper exposure.

Guide Number Equation - the equation is GN = aperture * distance. If you know the guide number and the aperture, you can determine the proper distance like this: distance = GN / aperture. Similarly, aperture = GN / distance.

K-14 - the photographic process for developing KodaChrome film.

Negative Space - area in a photo that is devoid of useful content or is otherwise uninteresting. Negative space is frequently blue or black water. Negative space is usually concentrated around the edges of the frame.

Reproduction Ratio - a number that represents the size of an image on film compared to the size of the original subject. A 1:1 ratio means that the image is the same size on film as the original object. 1:2 means that the image is half the size of the original object.

Shutter - the part of a camera that blocks the path of light between the lens and the film. The most common type of shutter is a focal plane shutter.

Shutter, focal plane - a type of shutter that operates by opening and closing a curtain just in front of the film.

Snell's Window - the cone of vision when looking upwards from underwater that allows viewing of objects on the surface. Inside the cone, you can see what's on the surface; outside of the cone all you see is the water.

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