| A | B |
|---|
| aperture | The size of the lense opening through which light passes. |
| shutter | A mechanism that opens and closes to admit light into a camera for a measured length of time. |
| ISO | A numerical rating that describes the sensitivity to light of film. |
| lens | A piece or several pieces of optical glass shaped to focus an image of a subject. |
| extension tubes | Metal rings that can be attached between a camera body and lens for close-up work. They extend the lens farther than normal from the film plane so that the lens can focus closer than normal to an object. |
| focal plane | The plane or surface on which a focused lens forms a sharp image. Also called the film plane. |
| f-number | A number that equals the focal length of a lens divided by the diameter of the aperture at a given setting. |
| depth of field | The area between the nearest and farthest points from the camera that are acceptably sharp in an image. |
| leaf shutter | A camera mechanism that admits light to expose film by opening and shutting a circle of overlapping metal leaves. |
| focal length | The distance from the lens to the focal plane when the lens is focused on infinity. The longer the focal length, the greater the magnification of the image. |
