Separation negatives and colour sensitivity

[laroygreen]

Hi everyone,

Hopefully a straightforward question - if you are using orthochromatic film for separation negatives of a colour transparency, can lower red sensitivity in the negative be compensated for by exposing the negative for a longer time to build density? I know this would require a lot of testing to prevent colour shifts, but in theory is this even possible? This is the response curve of the ortho film I am working with:

 

[koraks]

but in theory is this even possible?

I'd say so yes. One thing I'd check for a minute is overlay the sensitivity plot of your ortho film on top of the dye transmission plots of your color film, but I'm pretty sure there's plenty of 'red' information in the section where the ortho film still has sensitivity.

What I can NOT vouch for is linearity of the H/D curve of your ortho film in the part of the spectrum you intend to use it. I'd expect some trouble there, with cyan/red crossover in the final work as a result. You'd have to experiment.

Kudos for trying to do this the hard way! What's your process/application exactly?

 

[laroygreen]

Thank you @koraks. Trying to get into carbon printing without using a computer / scanner / printer (just a preference). Because of Customs, I am only able to get x-ray sheet film locally. I am trying to decide what makes sense before I embark on any testing to arrive at a conclusion that others knew for a long time . I believe I have everything else to be successful but while reading through Colour Photography in Practice and Modern Carbon Printing, panchromatic specialist films are what the authors recommend for carbon printing when working with separation negatives, which makes sense.

As a FYI, my goal is not to match / outperform any currently available process (including inkjet) or have perfect colour accuracy. So a few compromises here or there is fine so long as I can have some control over where those compromises are made (if that makes sense).

 

[koraks]

Trying to get into carbon printing without using a computer / scanner / printer (just a preference).

You don't have to explain, I know what you mean!

I thought about it for a while, but decided it would not be feasible, at least not with decent color fidelity and within a reasonable timeframe. Starting with color negative is another hurdle as opposed to color positive/E6 and I didn't really have in mind going back to that stuff anymore. I did think about the applicability of x-ray, but apart from maybe getting it to work as an internegative, I don't think it's much use given its wayward H/D curves. If you plot those out, you'll notice they barely have a straight part to them. The one you posted is a good example (now I see why it looked so familiar!) I considered something relatively affordable like Fomapan 200. This is also not necessarily perfect, but lots better already and panchromatic. I understand this isn't a feasible option for you, so it's out of the window.

If you go for a more artistic result, I imagine you might be able to get this to work. I imagine the results will be the kind of thing you see in 1970s screen printing work when that became accessible for the masses. It should be feasible and might be worth it if that's what you're looking for.

I'd recommend to just give it a go. I'd recommend also getting the carbon book by Sandy King, Don Nelson & John Lockhart and perhaps also Calvin Grier's gum printing manual. Neither goes into full-analog color separations, but they contain a plethora of relevant information even if you don't work with digital negatives.

Let me know how you get on with this. I'm currently working on a color carbon approach myself, which is slow and frustrating, but interesting overall. I've written a couple things about it on my blog; have a look, you may find one or two things relevant.

 

[DREW WILEY]

Might as well be attempting to stop a charging water buffalo with a BB gun. The short answer is, NO. You not only need a real panchromatic film, but ideally, a select pan film with the most appropriate linear and spectral response with respect to tricolor filtration. Otherwise, you might as well be jumping off a diving board with only rock below. Red is at 650mm; and you've already crashed well before that. Ortho and ortho litho are deliberately engineered NOT to see red.

 

[Sirius Glass]

Might as well be attempting to stop a charging water buffalo with a BB gun. The short answer is, NO. You not only need a real panchromatic film, but ideally, a select pan film with the most appropriate linear and spectral response with respect to tricolor filtration. Otherwise, you might as well be jumping off a diving board with only rock below. Red is at 650mm; and you've already crashed well before that. Ortho and ortho litho are deliberately engineered NOT to see red.

I like the comparison. I am a fan of cordless bungee jumping. It makes a great impression. There is a real impact. It provides great coverage.

 

[koraks]

Red is at 650mm; and you've already crashed well before that.

For Ektar, it should be possible to separate out the red at as low as 600nm. Below that will result in massive crossover.
Sadly, OP's film has 'crashed' before that as well.

 

[DREW WILEY]

Ektar is difficult to make separations from. Been there, done that. And anytime one starts with a color negative original, two tricky steps are involved. First you need to generate usable precise pan film RGB inter-positives - quite a challenge in itself - and then turn those into a matched balanced set of RGB internegs for sake of actual printing. I could cite an official Kodak pamphlet of yesteryear telling you exactly how to do that with a color neg original, ironically written by someone who never actually attempted it! Welcome to hell.

I've seen gorgeous color carbon and carbro work done the traditional all-darkroom style before scanners ever were available. But I know of only one person among those who had the expertise to routinely start with color negatives rather than transparencies, and he could afford to consume a lot of appropriate sheet film in the process because he was so wealthy to begin with.

 

[koraks]

Welcome to hell.

Well, I stood at its gate for a bit, peered inside and decided I quite like the chilly cold outside.

 

[DREW WILEY]

I was experimenting with separations from Ektar color negs usable for dye transfer printing, but walked away with expanded contrast results which worked a lot better for printing on black and white paper! At least the experiment proved worthwhile for something; and I kept notes, and have successfully done it a number of times since.

 

[laroygreen]

Thank you all for the guidance. I won't go charging ahead as the comments confirmed what I was reading. Its a lot to think about, but at least I wouldn't have been coming from a negative, but a transparency. There is a lot here to consider, but is there even a panchromatic sheet film, available today, that is considered good (or serviceable) for separation negatives of Kodak E100?

 

[gordrob]

I was going to suggest you look for some Kodak 100TMAX 4x5 film as it is probably the best film for making separations from transparencies until I looked on Ebay to see if there was slightly out of date film available and got a shock as to the price of what was available. You could check this web site for some of the better instructions on making separations. David Doubley and Bob Pace published books on Dye Transfer and they both contain a lot of information on how to go about making the seps. You may want t look to Drew for some other film options as I have only used TMAX film.

https://www.yumpu.com/en/document/view/40739636/the-dye-transfer-process-by-david-doubley

 

[laroygreen]

I slept on the confirmation that x-ray film won't get me to where I want to be, so I have a few more ideas that might be worth trying. As mentioned earlier, access to sheet film is difficult due to Customs' habit of opening boxes and I've lost 2 boxes of sheet film this way with no possibility of reimbursement. I believe if I can get a few boxes when next I travel and keep them in my carry on I should be ok, though I think the issue is that maybe when they scan film boxes they can't "see" whats inside due to some shielding? Worth a try I guess. Also, to offset the costs, I could do all my testing on 35mm film and once I have exposure, etc. dialed in, then I can move to using the sheet film to make final separation negatives. How does that sound? I can start with TMAX as @gordrob mentioned, and eventually move to something cheaper once I troubleshoot the rest of the process.

Thank you @gordrob for the resources and I will seek them out certainly. I've been collecting several books, articles and videos on carbon and dye transfer (as well as books on filters, etc).

 

[koraks]

I think the issue is that maybe when they scan film boxes they can't "see" whats inside due to some shielding?

There's a large thread about carry-on luggage scanners. But in my experience, no, security personnel won't be phased by film boxes I'd expect. Simply because a typical x-ray scanner will scan right through them so it's not an issue for them. If you ask for hand inspection you may or may not be lucky, depending on lots of factors. Slow film in a regular carry-on luggage xray scanner (non-CT) should in any case go through just fine and undamaged.

I could do all my testing on 35mm film and once I have exposure, etc. dialed in, then I can move to using the sheet film to make final separation negatives. How does that sound?

I think I'd do something similar, probably. Or maybe cut sheet film into smaller sheets. But yeah, divide and conquer

Drew has recommended FP4+ several times in the (recent) past as a cheaper and also quite acceptable alternative to TMX.

 

[MattKing]

As mentioned earlier, access to sheet film is difficult due to Customs' habit of opening boxes

Which Customs - i.e. which country are you in?

 

[laroygreen]

@koraks thanks for the recommendation and its quite a bit cheaper than TMX.

@MattKing the island of Trinidad and Tobago.

 

[MattKing]

@MattKing the island of Trinidad and Tobago.

A suggestion I make to most members: indicating at least your general location in your profile is really handy, because it informs the answer to so many questions we see here.
I'm going to respond with another question: Have you reached out to the Customs authorities to ask for direction about importing light sensitive materials used for both medical and, in your case, artistic purposes?
They may have internal memos on the issue that you could reference in your importation documentation.
Even listing the proper tariff code might do that for you.
My experience is with Canada Customs of course, not the Customs authority where you are, but in my experience all Customs Authorities love things like rules and internal memos!

 

[laroygreen]

Thank you @MattKing for the suggestions. Its worth checking again. Last time I spoke to a Customs officer they only had exemptions for medical material shipped by licensed companies but I didn't press the issue. I also think putting film in my carry on next time I travel might be the best option. At least I would have a chance to explain, maybe even have my dark bag with me if they want to check the film (I am optimistically assuming that anyone would stick their hand in some random persons "dark bag" )

I had spoken to an older photographer here (this is very old info) and he stated that back when he was running a studio (studio is still around, but digital), they would ship a pallet of photographic paper and basically would sacrifice 10 boxes or so for customs to verify that the boxes did indeed contain paper. Not feasible strategy for me, but I am hopeful I can find a way around this given panchromatic film is my only reasonable option.

 

[MattKing]

If there are any Customs brokers there, perhaps they can be persuaded to at least give advice to an individual, or to provide their services at a favourable rate.
What you are looking for is a policy memo about how to handle importations of light sensitive material - not an exemption per se.

 

[laroygreen]

@MattKing funny enough, I have to pick up some documents at a custom broker so I'll be sure to ask for their recommendation. Thanks for the suggestions! I'll post any updates,