A depth of field UNcalculator

How about just shooting digital, and bracket for DoF? Or knock one at
optimum aperture, and one more at minimum? Doesn't Rodenstock make a
calculator for the PDA-impaired?


"Bob Monaghan" wrote in message
...

well, the formulas for DOF calculators are readily available, viz.,
http://medfmt.8k.com/brondof.html has javascript on that page and so on;

if you have a hyperfocal distance, you can just use one formula, viz. see
http://medfmt.8k.com/mf/hyperfocal.html

for more on DOF math, see Michael Davis article on subject at
http://medfmt.8k.com/mf/dofmath.html and followup with Harold Merk.

if you are like me, you may prefer a graphical solution?
http://www.dof.pcraft.com/dof-frames.cgi

given you know the lens focal length and film format, you can simply
iterate CoC values in a flexible DOF calculator spreadsheet to determine
the mfger's COC values used in creating the table (or lens) values

An excellent example would be Michael Davis' not just another DOF
calculator ;-) at http://home.online.no/~gjon/mdofcal9.xls

After that, it is just a matter of iterating on COC until the table
matches the printed chart.

===== Liberal Lenses (w.r.t. DOF)

that said, I usually don't use DOF charts in the field, though they are
usually in the manuals which I do have with me, so I tend to rely on the
lens DOF markings but using generally a stop more conservative DOF points.

But as noted, not all lens makers use the same DOF COC values, so lenses
also tend to have more or less conservative DOF markings, depending on
which mfger or production run they represent (e.g., vivitars may vary
between makers even if still a 28mm f/2.8 basic lens ;-).

So in this case, it may be useful or important to note that a particular
lens provides a more liberal DOF range for a given f/stop and distance
setting. When this is the case, I mark in my own DOF markings as a warning
to me that the DOF markings on that lens is too liberal and I should
derate the indicated DOF by the amount shown by my added "tic" marks. This
is esp. important if you intend to do hyperfocal shots to be blown up very
large (beyond the point expected by most mfgers, e.g., 8x10" in many
cases?)...

hth bobm
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* Robert Monaghan POB 752182 Southern Methodist Univ. Dallas Tx 75275 *
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In article ,
"MikeWhy" wrote:

Doesn't Rodenstock make a
calculator for the PDA-impaired?

Yes, one side calculates DOF for level or inclined cameras at any ratio
between 1:1 and 1:20 + infinity. It sets CoC by choosing a film setting
from 35mm to 810 on the dial. It also has a mm scale to measure
displacement of the lens and the image on the viewing screen (some of
these a PDA would not do. + the calculator is faster then on my Tungsten
C).

The other side calculates Scheimpflug for and format from 35mm to 8x10.

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