Shallow focus is a photographic and cinematographic technique incorporating a small depth of field. In shallow focus one plane of the image is in focus while the rest is out of focus. Shallow focus is typically used to emphasize one part of the image over another. Photographers sometimes refer to the aesthetic character of the area that is out of focus as bokeh.
The opposite of shallow focus is the deep focus, in which the entire image is in focus.
The shallow focus has become more popular in the 2000s and 2010s. It is also a means by which low budget filmmakers use to hide places that would require expensive props. It is often proclaimed by some to being a way to avoid the "video look." Extremely shallow focus – sometimes called bokeh porn – made its debut in cinematography in 2008 with the release of the Canon EOS 5D Mark II and the start of DSLR cinematography.
The effect can be obtained by a larger aperture, a close viewpoint, a larger image sensor, or a longer focal length lens from a smaller distance. A tilt lens can be used, in the opposite way to that used to increase the depth of focus.
There are even adapters that allow lenses from 35mm cine cameras to be used in smaller film and digital formats.