Early Perutz and Agfa

[chris_livsey]

Reading the new Henri Cartier-Bresson "Scrapbook" I came across reference to the early film stock he used, Perutz and Agfa, and have been trying to find the speed of this stock, just curious, it was around 1932 when they first added numbering to the stock. I have got lost in the web and would appreciate any input.

[giordano]

I've got a 1942 book on miniature photography which cites the following examples (not Agfa or Perutz, alas). I've added the approximate ISO equivalents, and it gives an idea of how things looked then:

Slow (e.g. Kodak EF Pan): 12/10 DIN, 23 degrees Scheiner (ISO 16)
Medium fast (eg. Panatomic X): 15/10 DIN, 26 Scheiner (ISO 32)
Fast (e.g. Kodak Plus X, Ilford HP2): 18/10 DIN, 29 Scheiner (ISO 64)
Ultra (e.g. Kodak Super XX): 21/10 DIN, 32 Scheiner (ISO 125).

One reason the ISO values are approximate is that the three systems use different methods to measure film speed. Another is that in those days speed ratings tended to include a generous safety margin (towards overexposure, which made sense at the time, at least for medium and large B&W negatives which made up the vast bulk of the market). This was lowered by 1 stop some time after WW2, i.e. the published speed ratings of B&W films doubled with no change in the emulsion or processing. So in modern terms it may be appropriate to double the ISO numbers above.

[chris_livsey]

Thank you exactly what I was after.
BTW is it true that Kodak SuperXX became TriX when the "speed" was changed without an emulsion change ?

[giordano]

Originally Posted by chris_livsey

Thank you exactly what I was after.
BTW is it true that Kodak SuperXX became TriX when the "speed" was changed without an emulsion change ?

This Kodak's Venerable TRI-X Black-and-White Film Celebrates 50 Years says Tri-X was a new emulsion when launched in 1954 at ASA 200. Presumably that included the extra 1-stop safety margin, hence ISO 400 in today's terms, although the article isn't clear.

Wikipedia has a short Tri-X article but it's confused to the point of uselessness except for including the link above .

[chris_livsey]

As a by the by I found this list of Kodak film codes which does not appear on the Kodak site and may be of value to some.

Kodak Film Number to Film Type Cross Reference Table — Tom Philo Photography

BTW some sources suggest Kodak are confused and TriX was introduced before this date.

[gyoung]

Originally Posted by giordano

I've got a 1942 book on miniature photography which cites the following examples (not Agfa or Perutz, alas). I've added the approximate ISO equivalents, and it gives an idea of how things looked then:

Slow (e.g. Kodak EF Pan): 12/10 DIN, 23 degrees Scheiner (ISO 16)
Medium fast (eg. Panatomic X): 15/10 DIN, 26 Scheiner (ISO 32)
Fast (e.g. Kodak Plus X, Ilford HP2): 18/10 DIN, 29 Scheiner (ISO 64)
Ultra (e.g. Kodak Super XX): 21/10 DIN, 32 Scheiner (ISO 125).

One reason the ISO values are approximate is that the three systems use different methods to measure film speed. Another is that in those days speed ratings tended to include a generous safety margin (towards overexposure, which made sense at the time, at least for medium and large B&W negatives which made up the vast bulk of the market). This was lowered by 1 stop some time after WW2, i.e. the published speed ratings of B&W films doubled with no change in the emulsion or processing. So in modern terms it may be appropriate to double the ISO numbers above.

A 1937 Leica Manual gives 'Fast Panchromatic' as 23 Scheiner and 'Medium Fast Panchromatic' as 20-21 Scheiner, so a bit slower than the 1942 figures, the list of manufacturers of such films includes Agfa and Perutz as well as others.
Earlier films might be slower still.

Gerry

[chris_livsey]

1937 is exactly the period that is most interesting, thank you for taking the trouble to look.

[gyoung]

Originally Posted by chris_livsey

1937 is exactly the period that is most interesting, thank you for taking the trouble to look.

No problem, it sits on the shelf in my 'study'/darkroom/hell hole, and it's contemporary with my (inherited) III, so I have wallow in nostalgia now and again!

Gerry

[jaapv]

It is really sad- I have a box full of early 1950 slides from my father, Agfa and Perutz, And they have not held their colour well, Agfa went green, Perutz went blue. .

[gyoung]

Originally Posted by jaapv

It is really sad- I have a box full of early 1950 slides from my father, Agfa and Perutz, And they have not held their colour well, Agfa went green, Perutz went blue. .

Not unusual I think, Kodachrome stands up well, mine from early 60s are fine, somewhere I have some Perutz from about 1962, I will look them out and see whats happened to them.
The B&W negs from 1937-9 which came with the III are still in good condition though!

Gerry