Pyro Step Wedge

[Hans Berkhout]

I need a 31 step transmission step wedge that was processed in Pyro (PMK, Pyrocat HD). I'd appreciate detailed suggestions as to where/how to obtain this item.

I understand I may have to make one myself but why spend time reinventing the wheel?

Thanks in advance.

[Andrew O'Neill]

Contact print a step wedge onto your film of choice, develop in a staining developer, and presto, you've got what you wanted. But seriously, I don't ever recall seeing a commercially made pyro stained step wedge. Why do you need one?

[Michael R]

It would help if OP explained the goal. But yes, you'd have to make one, even if you're only looking for something generalized/illustrative. Assuming you want it to have any kind of meaningful application to your own work, the step wedge should be made using your own process, with the developer you use. Sensitometry with staining developers is tricky, so if the goal is to figure out how the negatives will print, you have to be specific with the process. For example, if you use PMK, a Pyrocat step wedge isn't going to be of great value. Etc. (you get the idea).

Hope this helps.

[Hans Berkhout]

Why? because I want to calibrate my dichro enlarger light source to print pyro negs with variable contrast paper. I have found Paul Butzi's calibration method very useful in this regard, with my D23 processed film.
See http://www.butzi.net/articles/vcce.htm

I could expose in camera but then I would have to cut my 31 step wedge in two pieces to fit a 4x5 holder- reluctant to do that (I'd fit a Expo Disc on camera lens and expose for zone IX).

Exposing under enlarger? I have no idea what EV to aim for, what exposure time, without running into reciprocity failure etc. I've done a few @ different exposure times and the resulting strips' higher or lower end don't always show separation. That's me reinventing the wheel. I'd probably get there. Eventually. Some precise advice would help speeding things up.

[Bill Burk]

Exposing under enlarger? I have no idea what EV to aim for, what exposure time, without running into reciprocity failure etc. I've done a few @ different exposure times and the resulting strips' higher or lower end don't always show separation. That's me reinventing the wheel. I'd probably get there. Eventually. Some precise advice would help speeding things up.

I was going to join the camp of "use the strip you got from Stouffer" but historically, Pyro was going to be considered the standard developer before D-76 became the standard... So there has to be value in having a Pyro developed master step wedge.

Hope you realized it... every step is a (a third stop ? in 31 step scales?) of exposure, you only need to adjust the time you tried... by counting the steps that show no detail... at least in the straight line section.

I always like to place the exposure so that two steps are completely clear on the negative, so that I can get good readings on the toe of the film. This is for a step wedge of the film's characteristic curve... not making a step wedge to use as a master step wedge.

So take your step wedge best effort and re-number in the opposite direction. You might not get all 31 steps... If some of your steps in the thinner densities measure exactly what you want, give them the numbers 1, 2, 3

For example step 20 might be 0.30, step 21 might be 0.20, step 22 might be 0.18 while step 23 is 0.10. So call 20 = 3, 21 = 2, "crossed out 22" and 23 = 1

[Ken Lee]

Why not purchase a step wedge, make your own contact print(s) on a few sheets of film, then develop them in your chosen developer ?

[ic-racer]

You don't need or want a stained step wedge to calibrate you enlarger head.

"Calibrating" a color head involves calculating what extra color density on the head is needed so all contrast ranges print the same gray. The calibration pertains to your paper and enlarger head. The calibration has nothing to do with your negatives or stain. If the stain in your negatives alters your ISO-R value in a print don't worry, as the ISO-R values are a range anyway. Besides, who prints to a ISO-R value anyway. You will be adjusting you contrast as needed for each individual negative, if they have stain or not.

[Drew Wiley]

You have to have your step wedge matched to the specific film and type of pyro you have in mind anyway, since different formulas yield somewhat different colors
of stain. Ordinary step wedges can be purchased with all the steps on a single piece of 4x5 film. If you contemplate this as an interesting project for some reason
or another, go ahead. But you'll be doing a bunch of complicated stuff that is utterly redundant in terms of getting good VC prints from actual pyro negs. It's like
trying to assimilate an auto repair manual before you've even got a driver's license. You're making things WAY more complicated than they need to be.

[koraks]

I've only just started darkroom printing, so I don't know anything, really. All I can tell is that I personally can only see the point in calibrating my enlargers with a step wedge if I were to do a large number of prints from negatives that are exposed and developed to exactly the same contrast, on the same film, with the same developer and printed on the same size, on the same paper. That would eliminate the need to do test strips for each negative. But since I work with haphazardly exposed and developed, real-world negatives on a variety of films and developers, I guess I'm comfortably stuck in the stone age where no step wedge will ever be able to help me

[Drew Wiley]

No, it wouldn't eliminate the need to do test strips. Every neg is a little different, and different brands of VC paper behave differently, even with minor changes in developer or even the specific mix of light color. And until you actually look at the final print, it's hard to judge what you need to do. Making test strips is super-easy anyway. Do yourself a favor and learn to work with just one film, developer, and paper first. Take your best guess and stick with that until you master the basics. Afterwards you can branch out. You're going about this backwards. Sure, there will be a few potholes along the road leading out of town. But that kind of thing has to be negotiated anyway. That's how you learn. If you enjoy the technical aspect to all this, that's fine too; but it can become a distraction that won't necessarily lead to better prints anytime soon. Just take it a step at a time and have fun.