Avery Pickford , Feb 01, 2010; 08:43 p.m.
What do you mean by sharpest? f/22 will have more of the picture in focus. So ignoring everything else, I suppose if this is what you care about you should always shoot at f/22.
In reality, you shouldn't ignore everything else.
You may WANT part of the photograph to be out of focus.
You'll run into other issues w/ using lenses at f/22 (which will depend on the lens).
And the big one...usually you don't have enough light to shoot at f/22 and still have a reasonable shutter speed.
Or maybe this isn't what you meant at all...