film speed scale
/ˈfɪlm ˈspiːd ˈskeɪl/
n
English · film speed scale中文 · 感光度刻度Español · escala de sensibilidad de la películaFrançais · échelle de sensibilité du film
意味：Graduated scale that shows the film’s sensitivity to light; it is expressed by the ISO or ASA number, where the higher the number, the more sensitive the film.