[pure-silver] Re: Good acutance and tonality for HP5+ 120 format
- From: Peter Badcock <peter.badcock@xxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Tue, 19 May 2009 13:48:33 +1000
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<http://www.ilfordphoto.com/Webfiles/2007321132461251.pdf>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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