Originally Posted by falconeye 
Yes, you don't.
Done my reading now, even though I hate being told to do a Google search that does not improve the signal to noise ratio.
It would seem that the definition has been reworked.
Macquarie Dictionary: "
depth of field,
n. Optics. The range of distances along the axis of a camera or other optical instrument, in which an object will produce a reasonably clear image."
Depth of field - Wikipedia, the free encyclopedia "The DOF is determined by the subject distance (that is, the distance to the plane that is perfectly in focus), the lens focal length, and the lens f-number (relative aperture)."
In many places on the web this definition has been extended to include other practical factors as Falk has pointed out. I think that using a new term or appending a qualifier to the term would make things much clearer. The original definition still has merit on its own. After all, the lens is still projecting exactly the same image on exactly the same area of sensor no matter what it is mounted on. What you and the sensor do with the image, or extra image area afterwards is another matter.