I would expect that a copy of the print would need to be taken (as opposed to the negative) as it has the dodging/burning etc, but how did they copy the print and what did they copy it to? Also how would they copy the layout of the pages. These days I assume they just scan and do the rest like any other thing digitally.
Continuous tone B&W photographs for newspaper or magazine reproduction using film, was an interesting lesson in failure at some important point in the production process, usually when you were already behind the deadline.
To answer your question directly, the copy was made with a film negative using a process camera, usually a gallery type of camera using either cut sheet film or roll film. The largest camera we had was a Klimsch Gallery Kamera from Germany which was capable of doing a 1m square negative. The film was held on the back of the film plane with a vacuum back. The screen ruled glass plate was some distance away in front of the film, I believe from memory around 30-40mm, in front of that was the screen dot aperture and in front of that was the lens with its own f/stop aperture like what you are familiar with on your camera.
One of the first things to realise is the screen ruling, which literally refers to a rule or line gauge, of so many lines, or rules per inch. There are of course metric rules for line gauges, but we’ll stick to inches. Rules per inch in normal wet ink printing parlance, is referred to as Lines Per Inch, (LPI).
For magazine work on quality paper stock, the minimum would usually be 150 LPI, finer stuff with better inks or processes, would often be 300 LPI. LPI can be higher, but by and large 300 LPI is usually adequate for most fine reproduction work using an analogue film process.
Essentially on the horizontal lines you would have around 150 LPI from the top to the bottom, with the vertical lines running from left to right at 150 LPI. On the best screens we had, all of these lines were on single sheets of glass and were manufactured in Germany. All other screen rulings we had, were on two glass sheets sandwiched together. Cheaper acrylic/polymer seemed to be a really good way to get the same quality as glass, but as far as our production house was concerned, those screens really didn’t cut the mustard.
The distance the screen rulings on the glass plates were away from the sheet of film also has an effect to the overall outcome; another variable.
The shape of the apertures can and did make a huge difference to the outcome and dependent upon the material being reproduced and the printing process down the track, the camera operator would select the most appropriate aperture shape. Generally though, most trade houses I was familiar with in the seventies, eighties and into the early nineties, would pretty much use the same type of aperture for everything.
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Duotone is what lifted many ink press reproductions above the ordinary and is normally used in B&W reproduction to expand the tonal scale. This is done by printing in two passes, usually using a black and grey ink. The light grey ink was laid down first, then overprinted using a dark black ink.
With this method, the difference between a single printing using a black ink and a duotone print, was often very noticeable. Usually the highlights retained exceptional detail, mid-tones were pretty much as they would have been with a single black printing, with the shadows also showing better detail.
Then to top it all off, one had to decide whether to print your duotone with a wet on dry print run, or a wet on wet print run. Meaning you print your first grey run, dry the ink (usually with a spray of a substance similar to talcum powder), then print your second run. Or, you print the first grey run, then print the second run with the ink from the first run still wet. For the record, I prefer wet on wet, but printers (in Australia anyway) always said wet on dry was better. Printers using German Heidelberg two colour machines, mostly it seemed, printed wet on wet with outstanding results.
The apertures are self explanetery. The Gallery camera showing the front you can see the lenses, the lights (ours usually were 3000W each side). Showing the rear of a different Klimsch you can see the film being held by the operator. It looks about A2 sized, or about broadsheet size.
Looking into the camera you should see a space where (on the left on all of our cameras) the screen glass was selected and rolled out to be in front of the film negative. The round dials would be for exposure, measured in seconds and minutes if required.
We had around 20 of these cameras in various places around Melbourne, not to mention the various vertical repro cameras which were all over our various departments.
Mick.