Definitions

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Those who are new to photography are likely to get lost in the blizzard of terminology and acronyms that starts when you read the owners manual for your first camera. Here is a list of terms you’re likely to run into and a (hopefully) simple explanation of what they mean.

Aperture

The size of the opening in the front of the camera which allows light to pass through the lens onto the film or CCD. Adjusting the aperture will have an effect on Depth Of Field.

CCD

While it sounds frightening, a Charge Coupled Device is more commonly known as an image sensor. It is to the digital camera what film is to the analog camera. It’s the piece that “sees” the light coming through the lens

Depth Of Field

The amount of a picture that is in focus. For example, let’s say you have two pictures of a pencil, with the point aimed at the camera. In one picture, everything from the tip to the eraser is perfectly focused, but in the other, the tip is perfectly focused, but starting about 1/3 the way down the length of the pencil it gets less and less sharp until, finally, the eraser is just a pink blur. The picture that is not completely in-focus has a shallower Depth of field than the other.

F-Stop

Refers to the way the Aperture is set. This is displayed as a fraction with the letter F as the numerator, i.e. f/4 or f/22. One point that still confuses me quite frequently is that, because this is a fraction, a smaller number (like f/2) actually describes a wider opening than a larger number (like f/22). Increasing the size of the aperture is known as “stopping down”

Focal Length

The distance from a lens’s surface to its focal point. Remember when you were a kid and on a sunny day you would use a magnifying glass and the sunlight to burn your initials into the wooden porch railing? (I Know that was you who did that…) The focal length for your magnifying lens would be the distance from the bottom surface of the lens to the smoking surface of the railing.

Shutter Speed

The amount of time the camera’s shutter is open and exposing the film (or CCD) to light. This is usually measured in fractions of a second (1/60 or 1/500, for example).