That's exactly it: a practical matter.
Forget all formulae and calculators, and use your eyes (is photography a visual medium?)
Select a subject. Decide what your picture is about.
Focus on that subject.
Then use the aperture to set how it relates visually to the rest of what is in the frame, judging not by table or scale, but by looking through the viewfinder to see how the sharp vs unsharp balance changes.
Yes, it is difficult when the groundglass gets darker and darker. But then, who promised it would be easy?
And to all those who say their subject stretches from the front lens to infinity, my response would be that such images are boring, and perhaps need not be produced in the first place. Just my view
But if you want to produce images without deciding what they are of anyway, just stop the lens down as far as it goes and be done with it.
But whatever you do, do not even think about DOF as a quantifiable entity. As something that can be discussed and decided upon separately, apart from the particular image your lens is projecting on your screen.
It quite simply is not.
It will always be either too much, too little, or just right.
But how much that is, is different every single time you create an image.
So just use your eyes and look.
Last edited by Q.G.; 07-21-2009 at 02:57 PM. Click to view previous post history.