Digital BW, The Print

>...if you shoot with a DSLR...depending on the lens and your sensor, 
>f8 to f11 is probably your best bet. 

I think the traditional emphasis on having everything in focus comes
from an attempt at simulating reality.  Our eyes see everything in focus.

As for what f-stop is needed to do that, of course it depends on the
format and focal length.  As for best sharpness, every lens has it's
sweet spot (or sweet range), so the idea is to use only enough f-stop
to get the needed DOF.  IOW, don't use f/22 if f/11 will do the job. 
Ideally the minimum required aperture will still be in the sweet range.

How does one know what aperture is needed?  One commonly used way of
doing that is hyperfocal focusing with the lens's DOF scale.  The
problem with 35mm lenses on DSLRs with smaller sensors is the DOF
scales aren't accurate (and many zooms and new "for digital" lenses
don't even have DOF scales).  I use Pentax 35mm Ltd prime lenses on a
K10 with an ABS-C sensor, so I can't use the scales.  However, there
is another way to do it using DOF tables.

Using an on-line COC (Circle Of Confusion) chart and DOF calculator I
calculated DOF tables for a whole bunch of focal lengths for this size
sensor (this size is used in lots of DSLRs).  I have been using these
in the field and they work beautifully.  I posted all the tables and
an explanation of how to use them in this on-line article

   http://www.cjcom.net/articles/hyperfoc.htm

It's easy to copy and print out the tables.  I keep a copy of
the ones for my lenses in the camera bag. 

I haven't used IR so I'm not sure what the issues are and whether
these tables will work for that.  But it's easy enough to make new
ones with the tools available on-line if you know what adjustments are
needed.  The article contains links to the DOF tools I used.

As for selective focus, that's an artistic decision.  But once you
have correct DOF tables for your setup, they should work just as well
for any desired DOF result.

I hope this helps.

Regards,
Clayton


Info on black and white digital printing at    
http://www.cjcom.net/digiprnarts.htm
I-Trak 2.0 coming soon