Basic Elements of Camera Lenses

There are few basic elements of lenses which needs to be familiar with. Diaphragm is the iris-type opening at the camera end of a lens. By changing the size of the opening in the diaphragm, you control how much light enters the lens, and therefore how much depth of field, or area of focus, is captured. The size of the opening is the aperture of the lens.

There's a wide range of focal lengths, or lens sizes, available for most dSLR cameras.