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Depth Of Field

Page history last edited by Air Dupaix 14 years, 7 months ago


Technical Definition

Depth of field, or DOF as it shall be referred to, refers to camera's ability to make certain portions of the z axis moving away from the camera remain in focus. This is mostly used in film and still frame cameras. DOF is the range of focus of light particles. Thus, the more narrow the aperture of a camera is the deeper the depth of field becomes (2). This translates to some things before and after a certain range are fuzzy or out of focus. Depending on how shallow or deep the area that is in focus it is called Shallow or Deep focus. These terms are mostly associated to film production (1). Filmmakers also change their DOF by zooming in or out on a certain shot with a set aperture. Zooming into a tighter shot of a subject with a wide aperture would flatten the background and the close-up shot would have a very shallow DOF with a very stark contrast of focus between the foreground and background. With a narrow aperture, more of the shot would remain in focus. Zooming out can have a similar effect depending on the aperture size; the shot can move from a tight shot to a wide shot with a narrow aperture and maintain a deep focus on what is revealed by the outwards zoom.


Aesthetic Applications

Now that we are past all the technical stuff we can talk about how this type of thing is actually used in film production. For one, Shallow focus can help draw the eye of the audience to a certain person or object without the use of a close-up.(1) This affect can draw the actions away from the distractions going on in the foreground and back ground. Or, it can be utilized within a close-up shot to enhance the viewer's attention towards the subject in focus: with one thing in focus in the foreground and only indistinguishable blurs behind it, attention will only be paid to the subject and with much greater focus than there would be if distractions could be seen in the background. There is also the common use of slowly or swiftly changing the depth of field to reveal something within a shot that was always there but just out of focus. And even beyond that fact, shallow focus shots just plain look pleasing to the eye. Depth of field is also a sign of a more expensive camera. In most movie recording cameras, there is no control of the aperture and therefore no control of the depth of field. It is the more expensive ones that day to day people can not afford that can be manipulated into showing depth of field and its array of uses. One thing that some hand held cameras can do is use a digital macro lenses that allows for limited use of depth of field (2).



Here is an excellent example of both the technical and aesthetic aspects of depth of field from 12 Angry Men. The shot begins with a very average shot and a somewhat shallow depth of field. We can see Juror #3 clearly as he stands, and Juror #8 who is closer to the camera is also in focus. The background is a little blurry, however; the pattern of the jacket is a little fuzzy and the design on the bathroom door is blurry as well. Then, as Juror #3 stands and walks towards the camera, the depth of field changes drastically as he gets closer and closer. The design on the bathroom door behind him turns from a somewhat blurry design to simple broad, fuzzy lines, and the jurors seated at the table become even more indistinguishable as he passes them and stands close to the camera. To achieve this, a fairly wide aperture must have been used, keeping Juror #3 in focus and blurring the background as the camera zoomed out to make space for Juror #3 to occupy. Aesthetically, this focuses the viewer's attention on Juror #3's face as he stares at the picture of his son. This quick moment of excellent representational acting is intensified by the shallow depth of field used, contrasting the sharp picture of Juror #3's face with a blurry background so all of the audience's attention is focused on the acting in the foreground rather than what's occuring in the background.




major edits

history of how this came to be and who used it first perhaps?



Works Consulted





Comments (4)

William Palm said

at 2:27 pm on Oct 20, 2009

oops.....I knew I messed that up. Sorry guys

Sean Desilets said

at 2:48 pm on Oct 18, 2009

Big factual problem: smaller apertures create *more* depth of field, as the image indicates.

Sean Desilets said

at 2:36 pm on Oct 18, 2009

I fixed the spelling. There may be some link issues.

Ian Stephens said

at 7:54 am on Oct 14, 2009

umm...the title has some spelling dificulites, but I'm not sure how to change it.

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