Aperture Priority: "A" on camera settings dial. An exposure system used in some automatic cameras in which the aperture is selected by the user and the appropriate shutter speed is controlled automatically.
Shutter Priority:a system used in some automatic cameras in which the shutter speed is selected by the user and the appropriate aperture is then set by the camera. Bokeh is the official name for a specific photography effect, seen below. The name actually comes from the Japanese word for blur or haze. It requires large aperture settings to get a good bokeh background (shallow depth of field). Large apertures let in so much light that there is much reflection and unfocused backgrounds occur. If you want a deep depth of field, everything in sharp focus, a small aperture would be used.