Before digital, I used to buy film in a store/shop saying "nnn ASA"
Then came digital and the 'net': now virtually everyone writes "ISO nnn"!
I understand that everybody and his dog knows what is meant by either ordering - but what if anything caused the transition?
Hi,
The International Standards Organization caused a lot of terminology changes over time. Not just things photography related.
Stan
Amateur Photographer
Professional Electronics Development Engineer
Interesting question that I'll admit I never thought about, but will provide my thoughts:
ASA is a reference to a fixed trait of an object, in this case, film. Yes, we could set the camera to a different ASA speed for special situations, but that usually required adjustment in processing later. The film itself obviously never changed and was defined by that number.
In the digital world, ISO is merely a variable setting, like many others in our cameras, and arguably reads better with the setting name first and the chosen value after.
From google AI:
Before the standardization of the ISO (International Organization for Standardization) film speed system in the 1970s, ASA was the primary standard used to measure film sensitivity to light in the United States and many other regions.
ASA (American Standards Association) and ISO are functionally identical in photography; for example, 100 ASA film is the same as 100 ISO film
The cause seems to be clear from first quote.
PS. I was used to GOST (государственный стандарт Союза ССР) and german films were measured in DIN (Deutsches Institut für Normung) :)
Hi,
There was a time when the film package stated it as ASA/ISO. I suppose to get folks used to the idea that they meant the same thing. Of course, the number was used on many cameras to set the metering to match the film. But one didn't change it while shooting until one changed the film to another sensitivity.
My early digital cameras all had film bodies with digital backs. The earliest ones didn't sport a connection between the two to automatically set the sensor ISO from the camera control. So that could lead to a mismatch far too easily. Later models saw the camera makers produce modified film bodies which then altered the sensor ISO from the camera ISO control.
In reality, the sensors have one or two actual equivalent sensitivity and the changing of the ISO isn't much more than slight of hand for the digital processing engine.
Stan
Amateur Photographer
Professional Electronics Development Engineer
ASA was regional (USA) designation for film sensivity like DIN was in Germany. In 1974 all has been changed to ISO (International Organization for Standartizaton) to create universal measurment for film sensivity.
