[Michael R 1974]

For example a scene with tree at 'infinity' and one at 6 feet. The tree at infinity needs maximum detail whereas the close tree can be out of focus and still be recognized as a tree. For me, when it is the other way around (the close three sharp and the infinity stuff out of focus) it looks odd. So I DO NOT use focal spread focusing when I want the stuff at infinity to be sharp. I focus at infinity. So, in the example above, focusing at 20 feet (the middle of the focus spread, but where there is no tree) is a little crazy in terms of making the images I like to make.

Thanks ic-racer. This is generally the approach I follow. Interestingly it is essentially what Merklinger calls "object plane focusing" (but done visually) - ie basing the point of focus and depth of field on the different objects in the scene and how much resolution they need.