How can one compute DEPTH OF FIELD????

just want to know how does one compute depth of field at a given aperture, focal length, and distance from subject??


this is coz i just shot some portrait pictures... used a 5D2 and a 24-70 2.8L .... distance was about 3-4 feet from subject focal length on lens was about 70 and opening was 2.8.... was surprised to some OOF blur on some parts of the subjects body .... focus point was the face i.e. eyes, nose.....


thanks

I guess you mean is there some simple formula you can use so you do not have to have a DOF calculator with you


or go to a web site like this


www.dofmaster.com/dofjs.html


Or have an application on your i phone that does it


Or as I have done, make a chart that shows all the DOF at all distances and aperture settings and try and commit them roughly to memory.

The Wikipedia article en.wikipedia.org/.../Depth_of_field has a lot on how to calculate the DoF...