RE: Best CI for process

Ryuji, As I read in your response I am drawn to "contrast for
negative materials". Now it is true that we use, or did, a silver based
product to hold our image (the negative) for printing. I was trying to point
out the term "useful" in the web sites explanation of CI. And if it is not
widely used out side of the halls of Kodak, perhaps, there is more useful
straight line area that needs to be considered for platinum, palladium, ...
It might look a little slanted or curved, but to the alternative receiving
media provides useful contrast information.

How about this, CIA ( Contrast Index of Alternative _prints) : )

I did extensive tracking of densities back in the late 80's and early 90's
of both film and prints. After observing the numbers as they related to my
final prints, I stepped away for absolutes and got more into the feel.

Etienne and I seem to have taken similar paths. While I was crunching those
numbers, creating charts, and looking at Kodak's film information in their
publication (I don't recall the publications # but it supplied one with
curves, CI, recommended developers and such). I too found a much more direct
way was to look at my graph of DR of the film and print interpretation,
either after throwing it on the densitometer or simply looking at it.

So back to shadow density in zone III.... Exposure for the shadows, process
for your highlights to match to ( insert scanner/enlarger/printing/ etc) and
have a nice day : )
   

Eric Neilsen Photography
4101 Commerce Street
Suite 9
Dallas, TX 75226
http://e.neilsen.home.att.net
http://ericneilsenphotography.com
 

> -----Original Message-----
> From: Ryuji Suzuki [mailto:rs@silvergrain.org]
> Sent: Saturday, October 01, 2005 11:16 PM
> To: alt-photo-process-l@sask.usask.ca
> Subject: Re: Best CI for process
>
> From: Eric Neilsen <e.neilsen@worldnet.att.net>
> Subject: RE: Best CI for process
> Date: Sat, 01 Oct 2005 21:35:38 -0500
>
> > This was quoted from the site referenced by Michael. Perhaps this is the
> > problem when talking about exposing prints. What is useful in silver
> > printing is not the same as what is useful for platinum printing. The
> > straightness of the line may differ but the underlying theme of useful
> > remains.
>
> The measurement technique for CI is a bit more complicated than that
> for gamma or average gradient. Criticizing the complexity of this
> process doesn't help at all because, roughly speaking, the CI was
> introduced as a more universally applicable measure of contrast for
> negative materials. Measures like gamma can certainly be used for
> graphic art material, for example, but the numbers wouldn't compare
> very well across different classes of emulsions. CI was aimed at
> broader applicability rather than simplicity of calculation.
>
> One may be able to come up with a simple measure of contrast, speed,
> etc. for a particular application. For example, log exposure range is
> a useful measure of contrast for b&w print emulsions because Dmax is
> pretty much the same for a particular surface. (This, of course,
> wouldn't be the case if the emulsion has pronounced toe or shoulder,
> as in old time emulsions.) One can find CI for printing emulsions but
> there is not very much use to do so, unless you are interested in
> comparing contrast of paper and other emulsions. Indeed, as far as I
> know, CI is not very widely used outside Eastman Kodak Company. Recent
> ISO standards are often written in spirit of gamma (slope of framing
> line of a D v. log E curve) or average gradient.
Received on Sun Oct 2 09:56:03 2005