what is depth of field in photgraphy?

Question

I need to know pure concept of depth of field and to implement on photography.

Answer 1

Depth of field is the range of distances within which an image is considered "in focus". Its value depends on the f-stop of the lens and distance to the subject and lens focal length. The larger the f-stop, (smaller aperture) the greater the depth of field. Depth of field is usually given in a table. Here is an example: http://www.btinternet.com/~g.a.patterson/mfaq/m_faq-10_2.html

Answer 2

Think of it this way - a pinhole camera has the smallest possible aperture, and everything is in focus - a HUGE depth of field. The larger the opening for a lens, the smaller the depth of field (things in the background are more out-of-focus, etc). However, the smaller the aperture, the longer it takes for light to create a good picture (a pinhole camera takes a VERY long time to get an image onto film, while an SLR takes micro-seconds). So, there's a trade-off there.

Answer 3

It is the portion of a photo that is in focus from front to back. The smaller the lens openning the greater the depth of field. That is why a pinhole camera does not have to be focused. Sometimes you want everything blurred except the central figure, then you use a large lens openning.

Answer 4

depth of field is the range of distances that are in focus for a particular optical system.
mathematically that would be either infinite in the case of a pure pin hole camera, or zero for any focussed optic, as in its focal plane.

photography, however, is not restricted to mathematical definitions though, its about art and composition.

in simple terms, the bigger the apature, the less depth of focus, near and distant objects (in relation to the focus) will be more blurred.
so, to increase depth you decrease apature, but then you need to increase exposure to get an image onto the film

Answer 5

It's the area from the foreground to the background that is in focus and it is a blending of F stop and Focal length.

Wide open a 35mm or 28mm wide angle lens goes 2 feet to infinity. If you stop it down to f/8 it goes under a foot to infinity.


Wide open a 55mm goes 6 feet to infinity

If you stop it down to f/5.6 it goes 3 feet to infinity If you stop it down to f/8 it goes 1.5 feet to infinity

A 90mm wide open has a depth of field of about 1/2 foot. If you stop it to f/8 this increases to maybe 15 feet. 3 feet in front of and 12 feet in back of.

Answer 6

Rather than explain it here, I am pointing you to a few sites.

http://www.cs.mtu.edu/~shene/DigiCam/User-Guide/950/depth-of-field.html
http://en.wikipedia.org/wiki/Depth_of_field
http://bobatkins.com/photography/technical/dofcalc.html
http://www.dofmaster.com/dofjs.html

While you are at it also look for "circle of confusion"...

Answer 7

Here is a really good and concise explanation for you:

http://www.cs.mtu.edu/~shene/DigiCam/User-Guide/950/depth-of-field.html

Answer 8

where focus points occur in measurable distances before and after the subject in the camera view..