Quote Originally Posted by Q.G. View Post
Now it is not true that DOF on film changes with field of view. When magnification and f-stop are constant, DOF will be too, no matter how large or small the frame.
Sorry, that's clearly incorrect for circumstances where the wider lens is even slightly near (or beyond) hyperfocal. Try it on dofmaster...at f22, 30mm @ 4ft. gives you 36.7 ft. of DoF vs. 300mm @ 40 ft. gives you 7.23 ft. of DoF. But at f2.8 it's only .91 ft. vs .89 ft.

Again, it is just f-stop and magnification, but it's magnification at the point whose focus is being considered, NOT magnification at the plane of best focus. Since you can't keep all of the magnifications the same for different FsoV you get different DoF results.