I did read Merklinger and found that most of what he said had no
relevance to the use of hyperfocal distance for landscape photography...
at least as I practice it.
Also, the comment below is only relevant for those who don't understand
what they're doing and the significance of the (unfortunately named)
"Circle of Confusion" value used in computations. Circle of Confusion
is more easily understood as its inverse... resolution, usually
expressed in line-pairs per mm. If you can find or derive the CoC used
in most DoF tables or calculators today you'll find that they vary from
about 30 lines/mm (0.033) to 36 lines/mm (o.028). Most modern films can
do much better than that. What those values still do indicate however
is not film resolution but the resolution limits typically attained by
*careful* hand held photography without IS. 40 lines/mm is about the
best that can be attained by an experienced photographer handheld and
without IS. 60 lines/mm is about the limit for most color films and 80
lines/mm for most fine grained B&W films. Given the right emulsion or
sensor one can achieve 100 lines/mm or greater provided the camera is
mounted on the Rock of Gibraltar.
But CoC is really about print size and human visual acuity. Once that
is determined you have to figure out if you can actually achieve it in
the field on film or sensor. If you understand what it is you can
determine what's reasonable for you or your intended audience. Then
apply it using a calculator that allows CoC or lines/mm as an input
variable. I posted a link to just such a calculator a day or two ago.
Chuck Norcutt
On 10/23/2014 7:43 AM, Piers Hemy wrote:
Let’s sum it up for today:
• The international depth of field standard, the basis for all camera
lens manufacturers to calculate their depth of field scales and
tables, dates back from a time, when image quality was severely
limited by the films available.
• Those who use depth of field scales, tables, and formulas (e. g.
for hyperfocal settings), restrict themselves – most probably without
knowing why – to the image quality potential of an average
pre-World-War-II emulsion.
I don’t believe that undermines anything that has been posted so far,
rather it gives some perspective (in the non-technical sense!)to the
different views expressed.
And once again, Merklinger’s writings are well worth the read for the
very different approach he takes.
Piers
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