I took the main thrust of the video …
Even in film time 35mm, 120, 220 and 4X5 film was bought in
large quantities to make sure that each format shared the same
batch production number — when tested to establish the "real"
ASA value, I was sure then that the whole lots had the same.
Then, since the emulsions were made to given specifications, it
was important to know the ASA.
This subject is worth more discussion than I am patient to type.
Have a good one, Mike… maybe later.