T-MAX interpositives too flat.

[Jin Grill]

I'm making some interpositives from color negatives using T-MAX 100 and T-MAX developer. The results are extremely low in contrast. What should I do in order to give me that extra boost in contrast without doing too much damage to shadow detail and adding too much grain. Should I switch to a D-19 developer? The desired end result is a well rendered B&W slide...or as close as it comes with B&W film.

thanks.

 

[Bruce Watson]

I'm making some interpositives from color negatives using T-MAX 100 and T-MAX developer. The results are extremely low in contrast. What should I do in order to give me that extra boost in contrast without doing too much damage to shadow detail and adding too much grain. Should I switch to a D-19 developer? The desired end result is a well rendered B&W slide...or as close as it comes with B&W film.

Normal B&W films will indeed make poor interpositives. The reason is that you need to get Dmax up in the 2.75-3.5 range to make a good solid black when you project the image to a screen.

Modern B&W negative films aren't made for this. They like a maximum density less that 1.5 or so. After that they begin to show interesting artifacts -- the "cooked" look. You'll get graininess increasing at what seems to be an exponential rate as density goes up, and you'll start to see what I think of as "ripples" around local high contrast boundaries (like that dark branch against the white cloud). And this happens with maximum densities of around 2.5 with Tri-X in my experience. The Tmax films should do somewhat better, but I'm not sure how much better.

IOW you are trying to use a film well beyond it's design parameters. So some artifacting shouldn't be a surprise.

The other problem is the color negatives' orange contrast masks. The B&W film will see this and record it just like you'd expect. To get a truer representation of the scene you need an interpositive film that would subtract this mask in the recording process. IIRC there were such films. Once. I don't know of any now. But I don't remember if they were designed to make high density range B&W transparencies. I doubt they were.

Sorry I can't be more help.

 

[keithwms]

My suggestion is to construct an exposure versus development matrix.

You expose the tmax, stripwise, by unmasking it under the enlarger in time increments. Then you snip the test sheet perpendicular to these strips and develop each test strip for different times (and/or in different developer dilutions if you feel so inclined). Thus you'll see which exposure/dev combo gives the results you desire or at least find out if what you want is possible with this film and developer.

If that fails, then yes, consider a different developer, but if you want an optimal slide then you'll need to make a test matrix anyway.

I agree that you probably aren't going to get the contrast index you want for top-notch projection, but you might get close enough.

 

[Photo Engineer]

Use D-8, D-11 or D-19 to get the contrast you need.

The interpositive contrast will be determined by your final use though.

PE

 

[Michel Hardy-Vallée]

I'm making some interpositives from color negatives using T-MAX 100 and T-MAX developer. The results are extremely low in contrast. What should I do in order to give me that extra boost in contrast without doing too much damage to shadow detail and adding too much grain. Should I switch to a D-19 developer? The desired end result is a well rendered B&W slide...or as close as it comes with B&W film.

Just a vocabulary note: an "interpositive" is a term usually reserved for a positive print that is, ahem, an intermediary. Like when you enlarge a negative. You enlarge your neg on sheet film, that gives you an interpositive, because you will then use that (intermediary)positive to contact print another negative. THEN you will print that enlarged negative onto a sensitized surface like say, cyanotype.

Anyway, for what you want, you should instead look at Kodak "Fine Grain Positive Release Film". There is a version on acetate (no. 5302) and one version on polyester (2302).

I got decent enough results by contact printing my 35mm negatives (which I usually print on paper) on 2302, then developing the latter in Dektol stock. You can do it in the darkroom, as the film is only blue-sensitive.

The resulting contrast is pretty good, but for optimal results, one would need to start with a more contrasty camera negative. That's what was recommended since the days of "lantern slides." The only issue with that process is that those contrastier negatives might be hard to print on paper.

EDIT: oh darn, I just saw you were starting from color negatives... Makes matter more complicated!

 

[dr5chrome]

Bruce;

Nothing could be further from the truth. most B&W films make perfect interpositives.

The key to a good interpositive is a good reversal B&W process. Control of the process is also key. If you are doing color negs to B&W interpositives a high contrast film should be used. Pan F or EFKE50 would be a good place to start.

as PE noted, a high contrast developer might help as well per you final use.

Also, a drum scan and LVT output will give you possibly the best result from a color to B&W neg.

dw

Normal B&W films will indeed make poor interpositives. The reason is that you need to get Dmax up in the 2.75-3.5 range to make a good solid black when you project the image to a screen.

Modern B&W negative films aren't made for this. They like a maximum density less that 1.5 or so. After that they begin to show interesting artifacts -- the "cooked" look. You'll get graininess increasing at what seems to be an exponential rate as density goes up, and you'll start to see what I think of as "ripples" around local high contrast boundaries (like that dark branch against the white cloud). And this happens with maximum densities of around 2.5 with Tri-X in my experience. The Tmax films should do somewhat better, but I'm not sure how much better.

IOW you are trying to use a film well beyond it's design parameters. So some artifacting shouldn't be a surprise.

The other problem is the color negatives' orange contrast masks. The B&W film will see this and record it just like you'd expect. To get a truer representation of the scene you need an interpositive film that would subtract this mask in the recording process. IIRC there were such films. Once. I don't know of any now. But I don't remember if they were designed to make high density range B&W transparencies. I doubt they were.

Sorry I can't be more help.

 

[Terrence Brennan]

Interpositives

Good morning, eh?

Okay, I have established my Canadian credentials...I used to use Super-XX Pan 4x5 to make interpositives, as an intermediate step to making B&W internegatives. Typically, these were used to make a large production run of B&W prints from a colour (NOT color) negative original for press kits, et cetera. Super-XX is gone, and it disappeared when we were still making internegatives, so we switched to TMAX-100 film. The internegatives were made on Professional Copy Film 4125, another fine film, also long gone. This film was sort-of like Vericolor (NOT Vericolour) Internegative film, in that the characteristic curve was upswept at its end. Sort of; Pro Copy had orthochromatic sensitivity only. The upswept curve in Pro Copy gave much better highlight separation, especially when making copy negs from B&W prints; a film like Plus-X or FP4 gave decent midtone separation, but the highlights were flat and muddy.

However, with Pro Copy, you would change the contrast not just with changes in development time, but also with changes in exposure. Overexposing this film would drive the contrast up, and that's what we would do in making the final internegative. It was normal to have a flat interpositive; that is necessary, to retain all of the information contained in the original negative. If the Contrast Index (CI) of the original negative was, about 0.60, and you exposed and developed your TMAX to get a CI of about 0.56 (approximately normal), the contrast of the interpositive would be 0.60 x 0.56 = 0.34...which is flatter than tea on a plate. To get a final negative from this intermediate positive, you would require a CI of 0.60/0.34 = 1.76, which will require a high contrast developer.

I haven't gone this route in a number of years, and today I would try making the final internegative on the same stock as used to make the initial interpositive. Development in a high contrast developer, like D-19 or D-11 would be necessary, to get the required contrast. If your original is large format, make the interpositive by contact, and the internegative by projection. This way, dust on the original will be rendered as light in the interpositive, dark in the internegative, and light in your final print, which can be spotted. Dust on the interpositive, when making the final internegative, will ultimately be dark in your final print, which will require negative retouching, and/or print etching and bleaching.

BTW, the developer we used to use for both steps was HC-110, dilution D.

 

[Bruce Watson]

Bruce;

Nothing could be further from the truth. most B&W films make perfect interpositives.

If your source is a color tranny, then I don't totally disagree. But the OP's source is a color negative. So the OP is using a standard developer process, not a reversal process. For the OP, the use of standard B&W films to make an interpositive from a color negative film is problematic at best.