[pure-silver] Re: Good acutance and tonality for HP5+ 120 format
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Mon, 18 May 2009 22:03:16 -0700
----- Original Message -----
From: Peter Badcock
To: pure-silver@xxxxxxxxxxxxx
Sent: Monday, May 18, 2009 8:48 PM
Subject: [pure-silver] Re: Good acutance and tonality for
HP5+ 120 format
It appears to an extent I have to trade-off linearity and
acutance, so I'll reduce my requirements down to just
acutance. So now....
Which developer (Xtol or Perceptol) will have the potential
to offer more acutance ?
Which other film developer might offer more acutance than
these ? (Rondinal or "Stand" developing excluded).
Finally, special thanks to the following people who replied:
To Bob who pointed out that I won't be able to get as long
of a straight line with HP5+ c.f. the tab grain films. This
is OK, as I checked the HP5+ characteristic curve on p.5 of
here and discovered about 7 stops of linearity [1] for the
nominal slope/contrast.
To Shannon's whose suggestion of the prints being more
romantic if I venture into the non-linear regions.
To Rob for the explanation of how developer dilutions affect
acutance and linearity.
To Myron for reminding me the paper curve should not be
forgotten about.
To Mark who reminded me the answers to my questions are
probably only result in minor gains.
I have previously thanked Cor and Jean-David.
regards
Peter
[1] Log(7)_base2=2.8 . The linear portion on the exposure
axis (E) goes between 1.4 to 4.2 =Log(E)=1.4 to Log(E)=4.2,
and 4.2-1.4=2.8=7stops. Developing for less time should
decrease the slope and slightly increase the length of the
linear portion along the exposure axis.
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