RE: Digital Carbon Negatives

For some reason I did not receive some of the messages alluded to in
this exchange, but to the extent that I can follow the topic here are
some observations.

I have not compared digital negatives of the type made by Keith
(pyro-color) with regular pyro negatives. I use digital negatives for
making carbon prints but they are not spectral negatives. However,
based on my understanding of how digital negatives print in general,
with kallitype and palladium as well as carbon, I can speculate with
some degree of confidence that a digital negative would print much
faster than a regular in-camera negative developed in a Pyro
developer because it would have much lower B+F and much lower density
in the shadows. Typically my digital negatives print in carbon with
both the NuArc 26-1K and a bank of BLB tubes in about 100-160 units,
where one unit equals one second. In-camera negatives take much
longer.

Which brings me to the second issue. Current generation Pyro
developers produce proportional stain, very little where silver
densities are low, much more where silver densities are high. Since
the stain blocks UV light the result is that Pyro stained negatives
print with more contrast than is apparent to the eye. In theory a
correctly exposed and developed Pyro negative will not take any
longer to print than a negative correctly exposed and developed in a
traditional non-staining developer. In practice that is usually not
the case, for two reasons.

1. Most people give more exposure than is necessary and this extra
density drives up B+F and Zone 1 and 2 values more for a Pyro stained
negative than for a traditional one. For example, an increase of one
extra stop in exposure will typically result in an increase in B+F
value with traditional negatives of about log 0.15, or about 1/2
stop, but double or even triple this for a Pyro negative. In other
words, if you over-expose the negative by one stop your printing
times with Pyro negatives will increase by between 100-150%.

2. Many people are using films that are less than ideal for
alternative printing because they have such a high rise in B+F from
the longer development times we must give them to get enough
contrast. Films like BPF and HP5+ are good examples. And of course,
as I noted above, an increase of 0.15 for a traditional negatives
becomes an effective increase of 0.30 to 0.45 for a stained negative.

What to do?

1. Don't overexpose. With the long development times needed to reach
the CI necessary for alternative printing most films should be rated
at full emulsion speed, or even higher. A very common mistake is to
reduce the EFS of the film thinking that this will give the density
necessary for alternative printing. But it is more contrast you need,
not more density.

2. Reserve films like BPF and HP5+ for medium and high contrast scenes.

3, Films that work well in low contrast lighting are FP4+, Tmax 400, Delta 100.

4. If you must shoot films like BPF and HP5+ in very flat lighting I
would recommend that you either develop the film in a Pyro developer
that does not produce a lot of stain, ABC Pyro at the 1:1:1:7
dilution for example, or use a very high energy developer like Kodak
D19, which you will have to mix from scratch.

Sandy King

>Hi Michael,
>>
>> I am planning on doing carbon prints from both digital and pyro
>developed
>> negatives this fall. I am wondering if anyone has done side-by-side
>> comparisons to the pyro color-balance formula Keith is using, and an
>> actual
>> pyro stained neg.
>>
>> Just curious.
>>
>> Did we meet at APIS?
>>
>> :)
>
>No Michael, I don't think that we did meet, I was very low key this year
>and not very out going that week since I was still grieving over the
>loss of my Norwegian Wood cat in May. :(
>
>When you use the phrase pyro generically I'm not clear what developer
>you are using. Assuming that your 'pyro' negs have the proper contrast
>index then they should work fine for carbon. If you mean PMK pyro than I
>would recommend not using it at all for any process used with UV
>printing, since the B+F levels required for proper contrast levels
>usually gets excessive.
>And PMK stain is too effective at blocking UV light causing
>extraordinarily long print times. According to Sandy King, PMK developed
>film to the proper contrast for carbon have very high levels of B+F.
>
>I know Sandy King has been quite successful making carbon prints using
>digital negatives produced by an inkjet printer. If you have not tried
>making alternative prints using inkjet negatives then you are in store
>for quite a surprise as they can print very fast. Contrast control is
>achieved through adjustment to the digi neg contrast rather than
>introducing a contrast agent of one sort or another.
>
>Specifically in the case of carbon printing with film based negatives
>contrast can be controlled by adjusting the dichromate concentration or
>as some printers do, by changing the proportion of gelatin to pigment
>percentage. If you are purchasing your carbon tissue the latter method
>of course isn't possible, so using a digi neg made be more desirable.
>Carbon prints made from digi negs look very nice but they don't have
>quite the presence of a print made from an original in camera negative,
>although most viewers will never notice.
>
>Perhaps our carbon experts can provide much more detailed information
>and correct any mistakes I've made in my reply.
>
>Best,
>
>Don Bryant
Received on Sun Mar 7 18:59:49 2004