Digital BW, The Print

In a message dated 11/22/2004 1:52:39 PM Pacific Standard Time,  
DigitalBlackandWhiteThePrint@yahoogroups.com writes:

From:  Steve Kale <stevekale@...>
Subject: Re: Digital f-stop  ranges and the print

Claude 

In the message below you seem to be  referring to more than simple
resolution.  Do you also mean the  recordable density range?  I would like a
hear a bit more on  this.  I have been spending a lot of time lately
understanding  graduated filters better (just ordered a set - yes I know I
should already  have been using them).  I would now like to understand how
film f-stop  ranges equate to a) the range of f-stops that can be recorded on
digital  sensor such as the 1Ds MK II and b) the density range that we talk
about  for our prints (Dmax less dMin).  As I understand it one of the  big
benefits of B&W film vs converted colour film is the greater tonal  range
that can be recorded by B&W film.  How does this range  compare with the new
digital cameras?  How much of this range is  printable?

Steve



Boy, you have opened a big can of worms here. Most of the color negative  
film (normal C-41 development) has a Contrast Index of 0.44-0.52, which means a  
1 stop luminance change in the scene records a 0.14 change in density in the  
film. Assuming no major color crossovers, from a pure monochomatic conversion 
of  the resultant lumped densities, you can get out to about 15 stops of 
luminance  before a shoulder apperars from the straight line and short toe of color 
neg.  films. This from a Dmin in the shadows of about .25 to a Dmax of r 2.38 
in the  highlights.
 
B&W films, especially Tmax (per my curve tests circa 1990) can vary  from 
3-11 stops with D-76 straight (I wild combinaton to tame I might add) and a  5-11 
minute development time. So with B&W, the Contrast Index (CI) varies  with 
development, as does the effective shadow thresholld speed, although not as  
much as you might think.
 
ISO states that you need a CI of 0.65 to get the box speed rating. Most  
Zoners develop their filme to a CI of 0.55 to match to the CI of #2 paper, which  
is a CI of 1.8 in an ideal world. So ISO essentially "pushes" the film a 
little  to get their rating, but real users have always derated their film at least 
2/3  stop with their "normal development."  So, with severe speed derating 
and  an extreme development "pull" you can get a lower CI than color neg. film, 
which  is fixed. This could also inhibit the Dmax of the film depending on the 
 developer and how it is agitated.
 
I have achieved densities in excess of 4.0 with Tmax developed in Dektol  
(not a misprint), but I never tested for linearity.
 
So, the recordable density range for B&W film varies all over the map  and is 
not necessarily superior to the 12 stop linear capability of some  sensors. 
Besides, with digital capture, you can easily increase the dynamic  range with 
a separate highlight and shadow range exposure to be blended later in  any 
ratio you wish.
 
This makes blanket statements, in either case, untrue without specific  
details of each method.
 
I prefer the speed and efficiency of digital capture with the  
creative/corrective post processes afforded by Photoshop, but that's just me.  I'm too 
impatient to go back to the darkroom for any reason. I earn my living  with "click 
to print" workflows of less than 1 minute for a 4x6 color print from  high 
speed dye subs, and I'm starting to do the same with Epsons, so maybe I've  been 
pulled too far the other way by digital technology.
 
I simply love color pigments AND BO/Quad/Hex/Sept/Oct monochrome inkjet  
output on various papers. What a great time to be in the "lightroom" with so  many 
great choices.
 
My handcuffs are long gone along with my toxic chemical dependency.
 
Claude


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