Interpositives v. direct positive/reversal for enlarged contact print negs

[kwmullet]

Would anyone have some opinion/facts regarding the relative quality of enlarged contact printing negs made with interpositives as opposed to those made by a direct positive process with reversal processing?

I've suspected that the potential of a process where you add a generation, such as when you contact-print a neg onto another piece of film to get an interpositive, then project that onto something like BPF200 to get your final contact printing negative is diminished compared to the potential of projecting the neg onto conventional negative film and reversal processing it for the contact printing negative.

I'd like my suspicions to be wrong. I'd like to find out that adding an interpositive, if done correctly, was little or no negative effect on the potential of the final print, regardless of whether it's Azo or an alt process.

After researching the reversal process, I haven't found a bleach recipe I'm really comfortable with. I'd like to hear from folks that have used the interpositive route to see if that's something that has as much potential as direct positive.

Thanks,

-KwM-

 

[waynecrider]

From what I have read at unblinkingeye.com part of it comes down to choosing developers for the interpositive and enlarged neg. http://unblinkingeye.com/Articles/EnlargeNeg/enlargeneg.html

In the article Negatives by Reversal http://unblinkingeye.com/Articles/NbyR/nbyr.html it notes that the primary difficulty with this technique is controlling contrast--special reversal films were usually recommended which are no longer available.

I have not read anything mentioning much more. Certainly no, "this is better then that", procedure. One of the lady's here teaches a course in enlarged negs. Maybe she'll chime in.

 

[Jim Noel]

I have just finished teaching a workshop on this very subject.

The making of an interpositive provides another level of control rather than the one provided by a direct positive negative.

The interposiutive should be flat with full info in both the shadows and the highlights. From this positive, a new negative can be made with any desirable contrast range.

I normally make 4x5 interpositives becaus they will fit into the enlarger which I use mnost often. Then they are printed to a new negative of whatever size I require at the time.

 

[Konical]

Good Morning,

I agree with Jim. I have never seen the point of bothering with a direct reversal process when it's so easy simply to make a positive transparency from a negative. Not only is there the extra flexibilty gained by adjusting the exposure/processing of the positive, it's also easy to make, for example, 35mm positive slides from negatives of other formats or enlarged positives from small format originals; when the originals are on 120 or sheet film, it's also easy to do some cropping and still retain good quality.

I did this years ago when I sometimes needed slides for classroom use or for some project in the graduate classes I was taking. At the time (this will date me a bit), I was using Kodak High Contrast Copy developed either in D-19 or Dektol 1:1; I assume that similar results would obtain with Tech Pan--if you can still find any at less highway-robbery prices. There is (was??) a Kodak film called Fine Grain Positive or Fine Grain Release Positive (never used it in 35mm) which was supposed to be good for making B & W slides. I do recall using that film, or something similar, to make 8 x 10 positives for use on an overhead projector. 8 x 10 Kodalith, by the way, also works similarly for that purpose if processed in highly-dilute paper developer.

Konical

 

[Aggie]

Yep I teach this as well. Both Jim and Koni, I agree with. BTW I get to teach it this fall on the University level. Helps when the guy who first taught me darkroom techniques now has me coming back to teach with him instead of being the student.

I find having the interpositive gives me more of a chance to tweak the negative into what I want. It's sort of (not exactly) like what we do to get the final print, only we use the result to make contact prints. I find it is fun to watch it all happen instead of having it in a tank and worrying if it turns out.

 

[kwmullet]

this is sounding good. I was hoping that my worries that (a) an additional generation of copy would reduce detail and "microcontrast" available in the final print and (b) that the base+fog of each generation of copy would diminish the potential for dynamic range would be fretting about nothing or at least making mountains out of anthills.

Would I be correct in believing that the dynamic range of film so far outstrips that of any print (silver gelatin, azo, alternate) process that any B+F density you gain by having two generations of copies is a non-issue?

-KwM-

 

[Kino]

KWMULLET, In my experience, with due diligence, your last statement is essentially correct. It might be frustrating at first, you will have to invest a fair amount of time and expense in materials to become comfortable in the process, but it is very rewarding.

The lab I work at copies several million feet of motion picture film a year from b&w original negatives, interpositives and even projection gamma theatrical prints, so I feel pretty confident to say so.

This is where having a wedge and a densitometry really comes in handy, but it is not essential. Since you will be dealing (I assume) with first generation negatives, the process won't be as tricky as say a 3rd generation 16mm reduction from 35mm release print negative printed on release print stock.

Good luck

 

[Aggie]

Quakecon is the first week in August. I may accompany my son down there to Dallas. If so I will bring my stuff and teach you how to do it. Just depends on if I want to spend 22 hours driving one way with my son and his invariable exhaust in a closed up vehicle not just once, but both ways.

 

[kwmullet]

very cool, Aggie. Even if you don't have time for a tutorial, we need to hook up and have coffee.

 

[Konical]

Good Afternoon, KWM,

Kino is correct, except that I don't think making B & W transparencies from original B & W negatives is necessarily either very frustating, time-consuming, or expensive, assuming that you are already familiar with basic darkroom processing. The learning curve is not, in my opinion, a very steep one, but I've had no experience with anything except original negatives from 35mm to 4 x 5 in size.

Ahead of any "tutorial" you may receive, you might prepare a simple apparatus to hold your originals (enlarger negative carriers and/or a copy stand can be an obvious part of it) and a lighting arrangement which will provide smooth, even lighting behind the negatives. If you're going to make 35mm slides, a slide-duplicating attachment or a macro lens would simplify things.

Konical

 

[nworth]

I have just finished teaching a workshop on this very subject.

The making of an interpositive provides another level of control rather than the one provided by a direct positive negative.

...

This is a mixed blessing, however. Although you have a bit more control, you also have more ways to screw up. If you are somewhat scatterbrained and careless, like me, the reversal route may (only may) be better. For the careful worker, though, I agree that the interpositive route is not that difficult. Since the interpositive is usually contact printed to the final negative, you do not lose any quality in that step. The cost may be somewhat higher, but bleaches are not cheap either, and the fuss of reversal processing is at least as great as the fuss of interpositive processing.

 

[kwmullet]

[...] Since the interpositive is usually contact printed to the final negative, you do not lose any quality in that step. [...]

Well, I guess I'd always assumed that the interpositive was made by contact printing the original neg, and that the interpositive was then projected onto the final sheet film for the final enlarged negative. Seems that would save on film costs, but I guess the best way to do this is something I'll eventually learn.

As great as all these online articles and forum threads are, there's some stuff I just need to learn kinesthetically.

I had one level of understanding of split contrast printing and would have probably stayed there forever but for Les McLean's darkroom workshop. Now, that skill has been kicked up a practical notch. There's no substitute for seeing it done and doing it with the right person/people looking over your shoulder.

-KwM-
​

 

[Jim Noel]

You may think it difficult, but, as Franklin P. Jordan said in 1938,
“I’ll take your word for how dumb you are, but even at that, you can learn to make a good copy negative in one evening.”

It is not a difficult or expensive procedure. It just takes attention to detail.

Obtain some lith film from freestyle, your favorite film developer at higher dilution, and go to work. Others will argue with this approach, but it does work. Are there other materials out there? Sure there are. For instance Ilford Ortho+ is a full scale ortho film which works very well. But you can learn the basics and make some good negatives with lith film.

I don't want to enter into an argument with others about the details of film, developers, etc., I just want to help someone get started.

If you desire more detailed info, PM me.
Jim

 

[Kino]

You can also make paper negatives if you want someting quick and dirty.

It drastically increases exposure times, but you don't have to buy any additional materials.

That's even easer than the lith route...

 

[Lukas Werth]

I have been making enlarged negatives form original 4x5 and 8x10 for some time both via interpositive and through direct reversal. I have settled for most of my negatives on the direct reversal procedure after Liam Lawness (try search engine, if it does not show up, I can provide details) with a few modifications.
For both procedures I have used, at least for the final result Arista Lith films from Freestyle.

First a general personal observation/opinion: For all I know, it is, contrary to common wisdom, possible to make via the analogue route, both through internegative and direct reversal, enlarged negatives which are in no way inferior to original in-camera negatives. It is quite difficult to get exactly the same contrast range, but this should generably not be desirable either: rather, weaknesses in the original neg may even be improved. However, making a first-rate enlarged neg takes time and dilligence.
I have limited experience in making digital negs, but know also the results of others, and I do not share the euphoria for them because: 1) it is neither easier nor cheaper 2) results often tend to have a "polished" look due to what I think is called periodisation (some fine in-between tones are skipped) 3) the procedure for me has principally the charme of building something with Lego-toys: the range of the resluts is pre-given by the elaborate forms of the material.

The basic reasons for why I settled on direct reversals are 1) the end result is achived in one continuous procedure, without intermediary drying/waiting for the next day, 2) I don't own a Jobo, and my procedure of developing the final negative takes ca. 45 minutes (intermediary movement after the first 10-15 minutes, but still rocking the dish at least every 3 minutes. This is too tedious for me as a common procedure, but this problem would be completely alleviated by a Jobo.

The basic problem with Liam Lawless direct reversal process as he describes it (and as it is described on the unblinking eye) is: when using contrasty original negatives, that is such which are already intended for contact-printing with, say, iron-salt processes, highlights tend to become very soft/lack contrast (regardless of how much pre-flash is used). This is because the lith film, when developed in the dillution specified by Liam, cannot handle this contrast range. Two solutions offer themselves, either alone or in combination: 1) build the final negatives from two films, one emphasizing the shadows, the other the highlights, achieved by a longer exposure. 2) develop in dillution 1:20 instead of 1:10, develope for at least twice the time: this way lith film can handle an amazing contrast range.
Another hint: I use the dichromate bleach bath (one dish, by the way, pouring in and out the solutions; saves place and the neg does not get dammaged by handling), but when the print is in the first water bath, whipe both surfaces with a soft hake brush. This goes a long way to remove silver residuals from - I suspect - the bleach bath, even when made up from distilled water, a problem which otherwise the more dilluted developer seems to aggravate.

These are my starting hints; I may be able to provide more information when needed/to specific questions.

 

[Aggie]

I should be in the Dallas area on the afternoon of the Second of August. I will be there until the afternoon of the 6th. So for those days, I can teach you when it fits into your schedule. I'll bring the films I have here to try. Just get some dektol ready. I also have the film holders in sizes 4x5, 5x7, and 8x10 to use for easels. Also depending on your printing methods (strong suggestion for Van Dyke it is very easy to do with this) have those chemicals mixed and ready to go.

 

[kwmullet]

Aggie, I'm taking this conversation out into the hallway, since it's of dubious value to the 13.3 thousand other members at this point.

 

[Thomassauerwein]

I'm also in the camp for inter-pos (4x5) to inter- neg (whatever size) It does take a concentrated learning curve and each image has its own needs in terms of expanded or condensed value range but the processs works great! I too find that a under exposed and/or extended value range works best for the inter-pos. I use Hc110 or rodinal for the negs depending on the vibe for the final image. The rodinal only for the inter-pos then back to Hc110 for inter-neg. Yes it is time consuming and it is necessary at times to re-make the negs to nail the proper value range but well worth the effort. I've yet to see the loss of sharpness that people attribute to additional generation negs but because I'm using emulsion (plat/Pall) on art papers it may not be a good test.