|I would never allow such close
zooming. That is what gigapixel panoramas are for.
This is simply a close up inspection.
The objective is to find the f
stop that will give you the greatest depth of field.
The next step is to repeat this
test varying only the focus. You would use the f
stop you find to work.
Shot with a Nikon D3s and a
Tokina 10-17 set at 15mm focused at the right edge of
infinity symbol (determined to be the sharpest setting
from and earlier focus setting test).
Images usually start to get
worse as the f stop goes up. This is due to
diffraction. I am surprised that this lens does
not show the typical diffraction at higher f stops.