A NOTE CONCERNING THE BOOKSHELF TEST PHOTOS
- my test procedure isn't very rigorous
- bad results may be caused by bad focusing as manual focusing in dim
lighting isn't any too easy when the DOF for this level of expected sharpness
is just a few millimeters in either direction
- the backs of the books aren't at exactly the same depth, the maximum
difference is about one inch. Only a few books at the center and at the
upper right-hand corner have been aligned - roughly.
- the test only shows that the specific tested lens
is at least as good as my results -- even that individual
lens might be better, and others of the same make and model may be
better or worse
- anyhow, the equivalent magnification of the 100% crops is just plain
sick, i.e. about 48x on a typical 17", 1024x768 CRT. Normally, 8x has been
considered a reasonable maximum for critical sharpness from film. At 48x
magnification, a 35mm film frame would be about 172cm (68") wide, and even
a 1.6x crop factor dSLR frame would be 107cm (42") wide!
Nothing Wrong with the Sharpness -- There Shouldn't Be!
(f/11 used to get a reasonable DOF at 2.4m as the backs of the books
are at slightly different depths, focused using a Canon magnifier,
tripod-mounted, remote release)
Note the cloth texture of the book to the right of the middle, the
width of the back is 20mm