Originally posted by keyser Is a larger format the answer? I thought DoF issues were MORE prounounced with a larger sensor... I mean, if you used a point and shoot, the DoF wouldn't be a problem at all.
With larger formats, DOF is more of a problem (because of longer lenses) but diffraction is less of a problem (because of larger frames). Ansel & Friends used f/64 on their 8x10" viewcams with long glass. Let's see, 'normal' on 8x10 is ~13" / 325mm, so 162mm (like my Wollensak Raptar 162/4.5) would be 'wide'. Those *must* be stopped down for decent DOF.
No, DOF isn't a problem with P&S's, because of their necessarily short lenses. But I once calculated diffraction limits for my P&S's and K20D. The numbers came out:
1.1mpx, 1/2.7" sensor, DL= ~f/6
5.1mpx, 1/1.8" sensor, DL= ~f/4.7
7.1mpx, 1/1.8" sensor, DL= ~f/3.9
14.6mpx, APSC sensor, DL= ~f/8.2
Going one stop tighter probably wouldn't affect images noticeably. A couple stops beyond there, it would likely be apparent to pixel-peepers. And a couple stops further, loss of sharpness should be visible in many enlargements.
Again, diffraction is a function of aperture, frame size, and sensor resolution; DOF is a function of aperture and focal length (among many other things); and distortion is a function of subject distance and focal length. Optimizing for all those is tricky. If it was easy, everyone would do it, eh?
____________________________________________
Anyway, macTak is on the right track: a medium-wide flatfield macro lens ~28mm at f/11 should give the sharpest results. But Pentax never made one! The closest would be a DA 35/2.8 Ltd Macro for around US$400, but it won't have the greatest DOF. It might be acceptable for shoes, though. Or look for a good Vivitar or Zeiss 28mm macro. Good luck!
Last edited by RioRico; 12-22-2010 at 06:17 PM.