Quote Originally Posted by ic-racer View Post
Just another note on the diffraction/DOF problem. As you increase you film format size (for the same size 'macro' subject mater) you are in a LOOSE-LOOSE situation with diffraction and DOF!

This (macro and micro photography) may be one field where the eventual development of small sensor technology will favor the 'Dark Side'
There are two ways to aproach photomacrography.

One is the 'frame-drive' approach, thinking of a frame as something to fill as its first goal.
Then you do indeed need higher magnification (= less DOF, but not necessarily more diffraction - depends on how much you stop down, of course) when switching to larger formats.

The other is the 'magnification-driven' approach, having a certain scale, and with it a certain level of detail, as its goal.
In this approach, larger formats mean more 'real estate' to fit the subject in.
Since DOF depends on magnification, not on format size, you do get the same DOF (assuming same f-stop). Diffraction then too does not change.