Why some people call the ISO or ASA film speed

[Bill Burk]

The first question is more intriguing to me.

For me the film ISO or ASA relates directly to how fast I go through film.

It takes me longer to shoot a roll of Panatomic-X.

I go through TMY2 much more quickly.

The film goes faster.

 

[AgX]

This is the most intriguing explanation to me.

 

[AgX]

Isn't there a risk that fast film overtakes the subject, leading to blurr nonetheless?