How can I calculate the change an extension tube makes to the maximum magnification of a lens? [duplicate]
Possible Duplicate: How can I calculate what the effect of an extension tube will be? My understanding is that extension tubes increase the magnification of lenses by reducing their minimum ...
I am pretty clear about that DOF depends on: Focal length Aperture Distance from subject Sensor size and more (as pointed in the comment). But what is the question here is: Is there any formula ...