How does Stouffer manufacture its step-wedges?

Just of of curiosity: what is the process they could use to manufacture wedges with a density of 3.0 (transmission)?
Does anybody know?

Tnx!

I have a vague memory of reading that they used an Ilford film, maybe Fp4+ or Ortho maybe?

john_s said:

I have a vague memory of reading that they used an Ilford film, maybe Fp4+ or Ortho maybe?

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I recall seeing the info on this, too. My memory is too vague to even guess what it was, though. It means that it's likely somewhere on the internet. Perhaps it was once on their web site?

mammolo said:

Just of of curiosity: what is the process they could use to manufacture wedges with a density of 3.0 (transmission)?
Does anybody know?

Tnx!

Click to expand...

Probably use a sensitometer with a lamp certified by NIST or ISO to read a certain number of foot lamberts, at a certain distance, exposing the film to an exact exposure period and processed to an exact gamma.

The old ones were on Kodak Super-XX. Modern ones more likely TMax, but FP4 could be hypothetically made to work.

Around the time Australian newspapers and magazine printing presses were switching over to metric halftone dots, we had some house branded LPM (Lines Per Millimetre) line screen resolution guides This was then sent to many magazine and newspaper printing establishments over the course of a year or so. Each place received two as we worked on the basis that the boss would covet one and place it in his/her drawer, while the other would be the one production staff would actually use. This is, within reason, what did happen.

This was around 1976/7/8 Stouffer manufactured them and I seem to remember the boffins at work reckoned they used one of Dupont's Cronalith Lithographic Films, not totally sure but I still have one that I used quite a lot back then. I think the minimum order was 2,000 units, or something like that. But we needed at least 1,000 in-house just to supply our own needs, whatever we ordered it was a lot as we had quite a few boxes of them.

The LPM units I've just discussed were not step wedges, so maybe that is why they used a lithographic film, I don't know.

Mick.

Thank you all, very informative. It seems that Stouffer is producing the step-wedges “one by one,” then. That is, the TP4x5 that I use is the result of someone at Stouffer shooting a 4x5 negative and developing it? Ok, maybe ten at a time, but still ….

Wow, I just assumed that there were some sort of automatic process to produce these step wedges.

Cheers

mammolo said:

Thank you all, very informative. It seems that Stouffer is producing the step-wedges “one by one,” then. That is, the TP4x5 that I use is the result of someone at Stouffer shooting a 4x5 negative and developing it? Ok, maybe ten at a time, but still ….

Wow, I just assumed that there were some sort of automatic process to produce these step wedges.

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What is the source for this information?

Someone I correspond with has received two quotes from Mr. Kevin Morris of Stouffer Industry re: what we are talking here. I report both verbatim.

"A step wedge can be made a few ways. We step and repeat on photographic film."

"We use overhead light sources, multiple exposure and tonal curve graphing."