Focus and sharpness

Focus? How hard is that?


Well, there's a choice between selective focus (with the subject sharp, and everything else out of focus); or 'deep field' focus (everything sharp from back to front); and the kind of compromise you are all too often forced to make, where your minimum aperture is limited by the need to use a shutter speed long enough to avoid camera shake or subject movement or both. Then there's the way that diffraction limits the maximum sharpness you can achieve anywhere in the picture, to say nothing of the whole vexed question of depth of field.


That's how hard it is.


On the other hand, there's a lot of the 'centipede walking' syndrome as well. You know that one: if the centipede ever took the time to work out how to move its legs, it could never move again. As usual in photography, it's 'shoot first, and ask questions afterwards'. But it's still useful to have thought about matters beforehand.

There will also be a separate module on soft focus and other ways of deliberately reducing sharpness, but these topics are also touched upon here.

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© 2007 Roger W. Hicks