[Alt-photo] Digital negatives help?

Don donsbryant at gmail.com
Tue Sep 27 01:22:51 UTC 2016


Good Evening Niranjan,

I'll attempt to answer your question(s) and make some comments though I
can't guarantee that my efforts will be completely helpful for you. To do
that, I'm going to dissect your post a bit and try to take the topics one by
one in my reply.

>
I had bought a box (unknowingly perhaps one of the last ones) of Chicago
Albumin’s POPs, which sitting in the my refrigerator all this time were
found to be amazingly still pretty good when I tested recently  So I thought
I will use it to ease in to the world of alt-processing by just focusing on
the digital negative and wet-processing without having to deal with coating
rods and blooming gelatin.  
>

First I've never used Centennial POP nor am I salt printer, but I would
suggest to you based on my interpretation of your post that your goal here
seems to be how to learn the art of creating digital negatives. Since I
don't know how much POP paper you have to work with my guess is that your
supply of POP will be exhausted somewhat quickly learning how to build your
negative for that material. 

So I would strongly suggest that you put your POP back into the refrigerator
and instead switch to silver gelatin printing since you are avoiding coating
your own papers for now, that is if you have a darkroom available. In the
event you only have a "Dim" room then perhaps you might wish to cut your
teeth on the cyanotype process.

At any rate I don't plan to get into the weeds with any particular process
but want to emphasize that your described digital negative creation
methodology seems to be quite meandering or least more than I care to
follow. :)

>
I am using ChartThrob, an old batch of Pictorico OHP Premium Film and HP
9180B
>

Since you are using CT, I assume you are editing with Photoshop. That being
said what color space are you using?

>
Things looked good but the white point could barely make it to an RGB of 205
or so on my scanner. 
>
You've lost me here, I've lost the context of your point to put it
succinctly. I could guess but I won't because you know what happens when one
assumes something.

Ok are you using a Stouffers step wedge (tablet) to determine the real
contrast range or density range of your print material? That would be the
first  major suggestion I would make to you.

Since you are using an HP printer I would also suggest purchasing a copy of
Mark Nelson's Precision Digital Negative. His Curve Calculator alone is
worth 3 times the cost of the package at least IMO. In addition, the
documentation provided about using colorized negatives is quite
enlightening. Additionally I wouldn't hesitate to get Dan Burkholder's
digital negative book as well. The two of those documents and so forth
though quite different in many ways will probably set you up with a good
foundation for making digi-negs. Now others may disagree but that's my 2
cents worth.

Okay the ball is back in your court so ask your questions - however try to
write concise postings and limit your questions to 1 or 2 at a time, doing
so will encourage quicker and probably more meaningful responses from me or
others who would like to respond.

Best of luck,

Don Bryant

-----Original Message-----
From: Alt-photo-process-list
[mailto:alt-photo-process-list-bounces at lists.altphotolist.org] On Behalf Of
Niranjan Patel via Alt-photo-process-list
Sent: Sunday, September 25, 2016 8:43 PM
To: alt-photo-process-list at lists.altphotolist.org
Cc: Niranjan Patel
Subject: [Alt-photo] Digital negatives help?

Don:
This post should be in the thread started by Henry Rattle with the same
subject line but I just (re)joined the group so I don’t have the previous
e-mails.  
In any case this is regarding the King/Harris technique you suggested to
Henry to get a higher Dmax from a digital negative.  First a background.  I
have been meaning to take up all these wonderful alt-processes for a while
now and had even joined this group for a short period almost a decade ago
(when I was still battling my inevitable succumb to the digital camera and
Photoshop) to learn from the great wealth of knowledge that is available
here for the taking.  Around that time I had bought a box (unknowingly
perhaps one of the last ones) of Chicago Albumin’s POPs, which sitting in
the my refrigerator all this time were found to be amazingly still pretty
good when I tested recently   So I thought I will use it to ease in to the
world of alt-processing by just focusing on the digital negative and
wet-processing without having to deal with coating rods and blooming
gelatin.  Ultimately, when I run out of POPs, I want to go on to Pt/Pd and
that poor man’s Pt/Pd - the salt printing. 
I am using ChartThrob, an old batch of Pictorico OHP Premium Film and HP
9180B (another dinosaur that won’t quit.)  At first I used the composite
black printing mode to learn the conversion curve (which incidentally is
pretty steep.)  Things looked good but the white point could barely make it
to an RGB of 205 or so on my scanner.  The unexposed paper processed in the
similar fashion (fixed in plain hypo and toned in Kodak Rapid Selenium
Toner) went as high as 240 or so.  So I did the colorizing tests where I
varied R and G in 5% steps in an 11x11 matrix (I didn‘t want to bother with
B at this point assuming B will be much more transparent than the other 2.)
 The result of that was indeed a better colors for a higher white point, the
best being around R/G/B of 51/128/0.  Now the 255 square (0 in the negative)
is reading about 225, much improvement -specially to the eye.  
Now I am greedy so I was looking for some other way to boost it even more.
 In comes your advise about adding a black fill layer that I promptly wanted
to try.  I did that on the ChartThrob 101 squares matrix with a Green layer
of 51/128/0.  Here is what I find:
After putting in the second fill layer and changing the blend mode to
Multiply and changing the blending options for the lower Green layer and the
opacity somewhat close to the numbers suggested, I end up with the square 0
in the negative to be, for example, R/G/B of 16/41/0.  With B still being 0,
this is still within the 11x11 matrix I did before where the best square was
found some where else.  
So the question is this:  Am I doing something wrong in putting together the
layers or in my analysis.  I am pretty sure at 16/41/0, it will end up
darker than what was already achieved at 51/128/0.
Sorry for the long-winded note.  And Hello to all on the list.

:Niranjan.
http://niranjanpatel.zenfolio.com/



_______________________________________________
Alt-photo-process-list | altphotolist.org



More information about the Alt-photo-process-list mailing list