Photography: Aperture priority (Diaphragm)

In most cases, lack of knowledge on the broad possibilities of DSLR cameras makes amateur photographers use the automatic modes only, missing many of their creative possibilities.
One of the available semi-automated settings in most modern cameras is the Aperture or Diaphragm priority. In most cameras, this setting is indicated by an "A" letter, but there are some exceptions - Canon, for example, indicates "Av" (from Aperture Value).