Making separation negatives from color positive sheet film

[pkr1979]

Hi all,

When making separation negatives from color positive film - how important is the black and white film you will use to make these separation negatives?

Considering costs I'd rather use Foma or Arista to do this instead of Kodak or Ilford.

Cheers
Peter

[koraks]

Ideally you'd use a film with good linearity from toe to shoulder. But in principle any panchromatic film should work.

[ic-racer]

If you are doing this you would have all the equipment to plot the H&D curves of the films in question exposed with your 3 filters and white light to see if they satisfy those criteria korkaks mentions.

[Mark Sampson]

Back in the day, Kodak recommended Super-XX for separation negatives, due to its very long straight line. Of course that film has been gone for 25 years- in fact I've heard that EK kept that film around only for dye-transfer which was discontinued at about the same time. TMX-100 might be your best bet today... and if you're thinking of dye-transfer, look up its practitioner Ctein. And perhaps Drew Wiley, or others here who have experience, will chime in. A complicated subject!

[pkr1979]

Thanks all,

I'm keen to get into carbon printing, but I don't want to use digital negatives. So I'm curious to know what kind of 8x10" BW sheet film would be suitable for making separation negatives from a 8x10" slide... at a reasonable cost (haha).

:-) Peter

[Drew Wiley]

Choice of film is quite important. I strongly recommend TMax 100. It was originally engineered as a color separation film, among its other applications. Works better than discontinued Super-XX. A distant second choice would be either TMY400 or FP4. In the long run, the best film will prove to be the cheapest due to far less waste and frustration. Still, it's a steep learning curve. Foma, Arista? Make a reservation in an insane asylum first - you'll be there a long time if you try to get those films to cooperate. I could go into the specifics of why not, but hopefully you'll just take my word for it.

[Jim Andrada]

I once tried to make screen printing "plates" by separation. I still suffer from the induced insanity. IIRC I was using a lith film of some kind. I really had no idea WTF I was doing but it was fun in a masochistic sort of way. Go for it.

[pkr1979]

Haha :-D I'll take your word for it. Tmax 100 it is :-) Thanks!

[Drew Wiley]

Undertake your learning curve with more affordable 4X5 T-Max, of course, rather than 8x10. Calibrating it is a lot like learning to play chords on the piano until you get things right. It takes time and seems awfully repetitious, but is necessary. Start with a carefully exposed 4x5 master chrome of a MacBeath Color Checker Chart. Trim this piece of color film back a bit to allow room to tape a 21-step step tablet onto the contact glass, outside the image area, so that both get reproduced on your color separation tests. Then make respective RGB contacts onto TMX until you achieve nearly perfectly overlapping curves with sufficient contrast for your intended purpose. Simple in principle, tedious to achieve, but once you've mastered all the preliminary fuss, it gets a lot easier to predictably replicate quality results with real subject matter .
Tricolor printing itself is a much more involved subject; and you'd want to defer to color carbon printing experts for those kinds of questions. Most now do digital color separations, but I've personally seen some wonderful carbon prints done completely darkroom-style; and of course, it's the only way it was done for decades prior to modern scanning options. You can also make in-camera separations for still-life subjects that don't move between exposures.

[pkr1979]

Thanks Drew. Im keen to figure out the completely darkroom-style way to do this :-)

[bob carnie]

I have seen Sandy Kings darkroom style tri colour carbons . He made a few and they are quite lovely. I would consider him a expert source on this subject