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.
Originally Posted by Satinsnow
And there's one slight exception that seems, at least to me, to have little practical significance. If the subject is, at the desired magnification, more-or-less at the short lens' hyperfocal distance from the camera then at that magnification the short less will get more DOF than the long one. Do the arithmetic. But that's a very special situation.