V1.02
Thom Hogan’s Complete Guide to the Nikon D300
Page 413
Thus, taking two Zeiss-based calculations for his favorite lens
where he needed 3’ (1m) to be in focus as his near point:
instead of using one aperture that said 2.73’ to infinity would
be in focus, he almost certainly would set his aperture one
stop lower and use the value that said 2.55’ to 134.44’ would
be in focus. The way he framed, infinity generally was a
smaller portion of the frame than the near point, anyway, so a
bit of softness at infinity actually drew your eyes forward to
the near interest.
Harold Merklinger’s
The Ins and Outs of Focus
(self-
published, ISBN 0-9695025-0-8) describes another depth of
field method that is based upon the object field. Essentially,
Merklinger’s thesis has you set the lens at infinity focus and
then use an aperture that is the physical size of the smallest
detail you want to render. For example, with a 50mm lens on
the camera, if you wish to resolve details as small as 5mm
(regardless of how close they are to you), you’d need to set
the lens to approximately f/11. (Please be aware that the
preceding is a gross oversimplification of something that takes
Merklinger an entire book to describe. A short summary of the
thesis is at
http://www.trenholm.org/hmmerk/DOFR.html
if
you want more info. To my knowledge Merklinger has never
taken the consequences of anti-aliasing into account—his
book predates digital.)
Sharpening
While technically not a “focusing” action, image sharpening
algorithms can increase the apparent acuity of a photo taken
with the D300.
Why is it necessary to sharpen images if the camera is
focusing correctly? The process of translating analog
information (light) into digital data (pixels) involves a
procedure called sampling. Edges of sampled objects tend to
be rendered in a manner that looks slightly fuzzy to our eyes.
plays upon those brain interpretations, while having a slightly soft near is in violation
of them.
