On Photography
I’d like a word with you…
By Robert de Gast February 8, 2008 San Miguel de Allende

Photography, the business of producing a chemical or digital image, has been burdened with lots of confusing words and names. In 1832, the enterprise was first named “heliography,” signifying, “drawing with the sun,” derived from the assumption that it was action of the sun which made the image. Shortly after, when it became clear that any kind of light, and not just sunlight, could be used to produce the picture, “photography,” meaning, “drawing with light,” entered the language. Photographers were called “camerists,” after the “camera,” the box and the lens that made the image possible. Before the end of the 19th century, the camera came to be called a Kodak, thanks to the brilliant marketing of George Eastman, founder of the Eastern Kodak Company and inventor of the role of film.

Other words and phrases crept into the language. “F-stop” became big, although its significance remained obscure. The term “shutter speed” gained popularity, as did “focal length.” Few people knew what these terms meant but they always sounded deeply important. The “speed” of film became a household word, although how “speed” came to be confused with “sensitivity” will forever remain a mystery.

Digital photography has introduced a slew of new terms to contend with. Here, I offer a glossary of some old and new terms and acronyms, and hope, thereby, to remove some of their mystery:

Aperture: an iris-like diaphragm opening that can expand and contract the lens to let you control the amount of light that passes through it, thus affecting the exposure. (It also affects depth of field—see below). The term “f-stop” is used interchangeably with aperture.

Aspect Ratio: the length of the longer side of the image compared with the shorter side. A 35mm film frame (24x36mm) has a 2:3 proportion. Some digital cameras offer 3:4 and 9:16 aspect ratios.

Burst Mode: a mode where the camera can take several shots (sometimes as many as 10) consecutively, usually in less than a second.

CCD: a charge-coupled device, which is the camera’s image-sensing component. It converts light into energy that can be stored as digital data in your camera

Depth of Field: the area of a photo that is in focus. The smaller the aperture (i.e. f/16, f22) the greater the depth of field. Conversely, the larger the aperture (i.e. f2.8, f/4) the shallower the depth of field.

Digital Zoom: a simulated zoom. You are magnifying the image digitally by cropping it and filling in the rest with interpolated pixels, thus degrading the quality. Even though the zoom ratio seems impressive, never choose a camera based on digital zoom.

Focal Length: always expressed in millimeters, this is the distance from the film plane to the optical center of the lens. It really refers to the angle of view the lens offers. The smaller the number the wider the angle. A lens with a range of focal lengths is called a zoom lens.

F-stop: see aperture. A fraction of the lens opening. Thus f-16 is 1/16 of the lens’ largest opening. Smaller f-stop numbers mean a larger lens opening; larger f-stop numbers mean a smaller lens opening.

ISO: the ISO (International Standards Organization) number indicates the sensitivity to light. The higher the number (e.g. 400, 800, 1600) the less light is needed to produce an image.

Robert de Gast has been a documentary photographer for five decades. He can be reached at 152-7396 or by email at robertdegast@hotmail.com.