Re: Best CI for process

From: Etienne Garbaux ^lt;[email protected]>
Date: 10/02/05-12:13:30 AM Z
Message-id: <p05210603bf651c1f98db@[192.168.1.100]>

Sandy wrote:

> I am truly baffled at your claims that it is
> possible to develop most modern films to a CI of 1.45 or more.
>
> Have you actually plotted curves with these films and done the
> calculations to figure actual CI, or are you basing your comments
> simply on Dmax figures? If you do the former you will see, beyond any
> shadow of a doubt that what you claim, i.e. CI of 1.45 and true
> density range of 3.0 or more, is an impossible proposition for most
> modern films. You may be able to coax that much CI out of a very few
> of the modern T-grain emulsion films, such as TMAX and Delta, but you
> will never get it from films the films from Eastern Europe, not even
> close.

Although I am familiar with CI, I do not calculate it. Frankly, I don't
see that it's all that much more useful than gamma. I'm a visual kinda
guy, anyway -- the curves speak relatively directly to me, and reducing
them to numbers (either CI or gamma) doesn't seem to add anything. If I
use one number, it's DR, not CI or gamma.

I've had transmission and reflection densitometers available at all times
since the late '60s, and have had an X-Rite 820 of my own since they came
out. I'm pretty obsessive about calibration and buy new calibration wedges
and plaques every 2-3 years. (Side note: All of my oy old ones, which
have been very carefully stored, still read exactly their original values
when the machine is calibrated with the new ones, so this degree of
obsession appears to be unnecessary.)

I used to plot film curves -- in fact I should have some around associated
with my tests of Pan-X, VP, TX, PX, and the older Ilford and Agfa films 20
or 25 years ago, though after at least 8 major and 5 minor moves, the next
people to see them will likely be my heirs! I adopted and further
developed a graphical method that I cannot remember where I first saw, in
which several graphs are put next to each other around in a square so that
the output function of one graph determines the input scale of the next.
It is a great way to see each step all the way from scene luminances to
print densities, as well as deriving the overall transfer characteristic.
Years ago, I had one such chart for each lens/film/development/paper
combination I used. Lately, I just check both ends of the range and
determine visually (with a wedge) that the toe and intermediate values are
acceptably linear.

Ever since the T-Max films came out, I've been making negatives with
highest densities of 3.0 to 3.3 and FB+F of around 0.3, with a good
transition from FB+F to Zones 0 and I and good linearity from there to the
highest densities. I just pulled some Plus-X negs I made in 1977, and they
have maximum densities of 2.6, FB+F of 0.4, with a good transition from
FB+F to Zones 0 and I and good linearity from there to the highest
densities. My recollection is that these were developed in DK-50 without
further manipulation, which is supported by the brownish tone of the image.
However, it is possible that they were intensified. The Pan-X negatives I
pulled are similar but with slightly higher maximum densities. When I
first tried the Eastern European films (I do not recall which ones) perhaps
8 years ago, I recall noting that they worked just about like Plus-X but
with many coating problems. I can't find any of those negs, and may well
have thrown them all away.

Best regards,

etienne
Received on Sun Oct 2 00:13:44 2005

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