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Re: [OM] BW films again - from Gary R

Subject: Re: [OM] BW films again - from Gary R
From: w shumaker <rlist@xxxxxxxx>
Date: Wed, 25 Sep 2002 11:50:32 -0400
From: Gary Reese <pcacala@xxxxxxxxxxxxx> 

I did a Zone System test of Fuji Neopan ACROS with Rodinal 1:50, at
push, pull and "normal" development. The results showed me that the
"OM-4 family" approach to Highlight and Shadow biasing, which seems to
work good for color, does NOT for B/W, or at least for Fuji ACROS.
Here's why: Zone III is the critical shadow zone for shadows which still
show texture. That seems to be what Olympus wants us to take shadow
readings from. But for three different development times on ACROS, it
was only 1 1/2 stops down from 18 0rey (Zone V), not 2 stops like the
Shadow button gives. Don't underestimate that 1/2 stop difference, it
makes a big difference in rendering shadow detail.  Use that button and
you need to meter instead on something you want to be in Zone II, the
threshold zone for a shadow with something in it, but nebulous and
hidden.  Conversely, the highlight button bias of 2 1/2 stops falls way
short of Zone VII, which is the brightest highlight with full texture
still evident. That seems to be what Olympus wants us to meter on. All
the development times I picked resulted in Zone VII being way more than
2 1/2 stops away from middle grey - more like 3 1/3 to 4 1/2 stops. Use
the Highlight button and you need to meter off something which is Zone
VI instead, like typical Caucasian skin or concrete buildings in
overcast. Zone VI can hardly be considered a Highlight!  Finally, if one
meters the easy way (averaging), one needs to know the Exposure Index
for their particular developer and development time, least you get too
many shots with insufficient shadow detail or too many with blocked
highlights.  Going with the manufacturer's film speed will tend towards
the shadow detail problem. Going with the manufacturer's recommended
developing time will tend towards the highlight problem, especially if
you use a condenser enlarger. Recommended development times are
typically for a diffusion enlarger (like with a color head), which
requires a higher contrast negative.  The combination of the two leads
to BOTH blocked highlights and empty shadows. It is that double whammy I
consistently see in student's work because they are developing for
diffusion enlargers and relying on inflated ISO ratings.

I also discovered that my approach to averaging a Zone VII highlight
spot reading and a Zone III shadow reading will make the exposure fall
well off the 18% middle grey mark (Zone V). It lands in Zone VI, thus
leading to underexposure and loss of shadow details.

It took me two days of testing, but I'm now confident I can make MUCH
better B/W prints from my ACROS/Rodinal negs. I put off doing such tests
for 30 years and in retrospect regret it.  There is a lot to be said for
the need to under develop and overexpose in normal contrast situations
and most definitely in high contrast situations.  Anyone can get a shot
in low contrast light, though.  That's forgiving.

Gary


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