Aperture refers to how much light a camera can let in at a given shutter speed. A larger aperture, denoted by small numbers such as F2.8, lets more light in then a small aperture, denoted by larger numbers such as F8. Aperture also affects the distances that appear to be in focus when a picture is taken. This is called depth of field (DOF).

Shutter speed is the duration for which a camera can record light to take a single picture. The shutter speeds of a camera are described as a range measured in seconds and fractions of a second. For example, if the shutter speeds of a camera are 1/1000 to 4, then it can take pictures from 1/1000th of a second to as long as 4 seconds.

Films for traditional cameras come in different sensitivities to light. The ISOs of a digital camera refer its equivalent sensitivities. A higher ISO rating means more sensitivity to light but produces pictures with more noise which is similar to pattern of film grain.

Move your cursor over ISOs to see the difference

The focal length is a measurement determined by a camera's lens. When measured in 35 mm film equivalent, it serves to determine the angle of view of  pictures taken. The smallest the equivalent focal length, the wider the angle of view and vice-versa. Optical zoom is the ratio between the longest and the shortest focal length. For example, a lens that is 35-105 has a 3X optical zoom, so does a 50-150 lens. The difference is that the 35-105 equivalent lens sees wider, the 50-150 sees further. Depending on the subject, focal length may be more important than optical zoom. Photographers of architecture typically prefer lenses with shorter focal lengths.

When a lens is mounted on a DSLR, it shows a different angle of view than it would on a 35 mm film camera. The focal length multiplier, sometimes called crop factor, is the ratio between the focal length of the lens and the focal length of a lens which would give the same field of view on a 35 mm film camera. The focal length multiplier is used to determine the angle of view of a lens on a DSLR.

Normally, digital cameras focus automatically before each picture is taken. This is called autofocus. Digital cameras can also have a manual focus mode to manually select the focus distance. Manual focus is useful in situations when the camera cannot properly focus automatically. It is also useful to take pictures faster when the subject distance is known. Instead of manual focus, some cameras have an infinity focus mode which sets the focus distance to infinity, others have a pan focus mode which sets the closest focus possible so that everything beyond that point is acceptably sharp.

All digital cameras can store their images in the JPEG format. This is an excellent choice because these images are easily viewable on any computer, lots of hardware devices for displaying images and even some DVD players. This is sufficient for most users.

For the needs of advanced photographers, some cameras can optionally save their images in RAW or TIFF file formats (or both).