Quote Originally Posted by Dan Fromm
Sigh. DOF is controlled by magnification and aperture, focal length has nothing to do with it. There's a widely-held misperception that longer lenses give less DOF than shorter ones. True, if one takes the same, but narrower, picture with the longer lens from the same shooting position, but the reason this happens is that the longer lens is giving higher magnification. Step back with the long lens to get the same magnification and you'll get the same DOF.


Focal length equates manification, which in shooting the same subject at the same distance you will have less depth of field, one other way to increase magnification is macro extention tubes, or special close focus designs, which will also yield less depth of field, which of course is a different subject.