[alt-photo] Re: Flatter than pure palladium?

etienne garbaux photographeur at nerdshack.com
Wed Oct 6 05:10:02 GMT 2010

>Etienne. I don't understand what you mean by contrast masks and a google
>search didn't really help with anything in the context of printing in this
>manner. Could you explain what you mean.

The basic idea is that you sandwich the negative emulsion-to-emulsion 
with an unexposed sheet of film.  Copy film is best, if anyone still 
makes it -- it is [was] typically a long-scale blue-sensitive film 
similar in speed to enlarging paper -- essentially, a #0 or #1 paper 
emulsion on a clear base, and very slow in film terms.  Some was even 
contact-printing speed (even slower).  Expose the copy film through 
the original negative, then develop it.  You're not aiming for a 
full-range positive, but rather for a very thin, low-contrast image, 
typically with substantial areas of clear base.  Finally, sandwich 
this with the original negative, emulsion to emulsion, in perfect 
register, and print.  You adjust the exposure and contrast of the 
mask to get the combined DR you are after.  Because you are adding 
density, expect significantly longer printing times.  Also, you need 
to be somewhat careful to use point-ish light when you expose the 
print, since the image on the film/mask sandwich is separated from 
the print medium by the base of the mask.  If you use [for example] a 
light box, it will reduce the sharpness a bit because light "leaks" 
around the image during the exposure.  One can achieve absolutely 
incredible flexibility using contrast masks, but there is a learning 
curve.  Back in the day, the good custom labs used contrast masks all 
the time.  They were also used in color printing to adjust the 
contrast of the three primary colors separately.  Now THAT was 
tedious!  (Ask me how I know....)

A register punch and frame are very, very helpful throughout this 
whole process -- punch the neg and the unexposed copy film, then use 
the frame to align them for printing.  It can be done manually on a 
light table, but it's tedious.

Note that if you introduce a bit of blur into the mask, it adds edge 
effects (i.e., accentuates edges -- what folks often call "local 
contrast") in addition to the overall (global) contrast 
reduction.  This is called "unsharp masking," and with film it was 
done by putting a layer of thin, very lightly textured mylar between 
the original negative and the copy film before exposing the copy 
film.  If you do masking "manually" in Photoshop, you add a little 
Gaussian Blur to the mask.  But unsharp masking is NOT what I'm 
talking about.  Straight ("sharp") contrast masking is what you would 
do for the billboard neg.

One final question, before you go to a lot of trouble:  Are you sure 
you have detail in the billboard on the neg -- it's not just 
blocked?  I don't think of Tri-X as capable of producing outlandish 
densities without blocking (it's not as bad as HP-5 in this regard, 
but it doesn't come close to the tabular-grain emulsions), and I 
question whether any Tri-X neg that outruns the exposure scale of 
pure Pd will have any highlight detail.  Hopefully, it's there.  I 
like the image.

Best regards,


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