Templates for film test with 4x5 sheet film.

Ian Grant

Well-Known Member
Registered User
The reason why there was an extra stop safety factor built in to the early pre 1960's ASA/BS standard was simply because whne it was introduced few if any had light meters so accurate exposures were more difficult. There were in fact two standard ASA/BSI Log and ASA/BSI arithmetic, Ilford films were sold with the BSI log speed, FP3 was 29º, HP3 32º

By the time the aASA/BSI standard was revised in 1960 exposure meters were common the safety factor was no longer needed, but there had been other changes largely in technique pioneered in Germany by people like Hans Windisch in his book Die Ney Foto Schule, also published in English as The New Photo School. Essentially with the advent of exposure meters accurate exposures were possible and to get teh best from 35mm cameras and films exposures and development times needed to be optimal. Over exposure and over development increase apparen grain and also reduce sharpness farbmore critical with 35mm than with MF and LF. One of the main advertisers in Die Neu foto Schule was Gossen with a range of meters.

Film technology was a generation ahead in the UK at Ilford and also Gevaert in Belgium and Agfa in Germany. Fine Grani Panchromatic (FP)and Hypersensitive Panchromatic (HP) films were introduced by Ilford in 1935 and these were the first generation of the modern conventional films we have today, Kodak's equivalentrange of Pan X, Plus X, SuperXX and Tri X were released in 1939 but by then Ilord had jreleased their improved second generation FP2 and HP2. Tri-X production ceased during the war probably because a key component had come from Germany, it had only been available as a sheet film. Kodak Ltd had made their films in Hungary as well asthe UK but the Hungarian factory was under Agfa control during the war and nationalised after WWII, becoming Forte.

Ilford's third genertaion of modern films FP3 and HP3 were introduced in 1943 both films I used while at school. As techniques were refined quite dramatically so did papers to match the thinner less contrasty negatives. If you've ever tried printing older pre WWII negative or plates you'd realiase just how dense and contrasty many are and they don't print well on modern papers because evolved along with changing techniques to better match negatives.

Another reason for the older use of more contrasty negatives had been to overcome the lower contrast of some lenses before coating became standard after WWII, uncoated Dagorsor Protars had excellent contrast, Tessars and similar a slight but noticeable drop, and Dialytes a significant drop.

So with improvements in technique aided by the wide spread use of meters hand held or on camera, and coated lenses the extra safety factor was no longer needed.

Ian
 

thronobulax

Active Member
Registered User
The reason why there was an extra stop safety factor built in to the early pre 1960's ASA/BS standard was simply because whne it was introduced few if any had light meters so accurate exposures were more difficult. There were in fact two standard ASA/BSI Log and ASA/BSI arithmetic, Ilford films were sold with the BSI log speed, FP3 was 29º, HP3 32º

By the time the aASA/BSI standard was revised in 1960 exposure meters were common the safety factor was no longer needed, but there had been other changes largely in technique pioneered in Germany by people like Hans Windisch in his book Die Ney Foto Schule, also published in English as The New Photo School. Essentially with the advent of exposure meters accurate exposures were possible and to get teh best from 35mm cameras and films exposures and development times needed to be optimal. Over exposure and over development increase apparen grain and also reduce sharpness farbmore critical with 35mm than with MF and LF. One of the main advertisers in Die Neu foto Schule was Gossen with a range of meters.

Film technology was a generation ahead in the UK at Ilford and also Gevaert in Belgium and Agfa in Germany. Fine Grani Panchromatic (FP)and Hypersensitive Panchromatic (HP) films were introduced by Ilford in 1935 and these were the first generation of the modern conventional films we have today, Kodak's equivalentrange of Pan X, Plus X, SuperXX and Tri X were released in 1939 but by then Ilord had jreleased their improved second generation FP2 and HP2. Tri-X production ceased during the war probably because a key component had come from Germany, it had only been available as a sheet film. Kodak Ltd had made their films in Hungary as well asthe UK but the Hungarian factory was under Agfa control during the war and nationalised after WWII, becoming Forte.

Ilford's third genertaion of modern films FP3 and HP3 were introduced in 1943 both films I used while at school. As techniques were refined quite dramatically so did papers to match the thinner less contrasty negatives. If you've ever tried printing older pre WWII negative or plates you'd realiase just how dense and contrasty many are and they don't print well on modern papers because evolved along with changing techniques to better match negatives.

Another reason for the older use of more contrasty negatives had been to overcome the lower contrast of some lenses before coating became standard after WWII, uncoated Dagorsor Protars had excellent contrast, Tessars and similar a slight but noticeable drop, and Dialytes a significant drop.

So with improvements in technique aided by the wide spread use of meters hand held or on camera, and coated lenses the extra safety factor was no longer needed.

Ian
Fascinating. Thanks for that. I have an uncoated Elmar for my Leica IIIf and can attest to the lower contrast (in some settings).
 
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