Film sensitivity
The Film sensitivity table gives the match between the sensitivity scales used over time for films and sensors. Open it from the side menu, in the tables section.
The scales
Section titled “The scales”| Scale | Origin | Principle |
|---|---|---|
| ISO | current international standard | arithmetic: doubling the value doubles the sensitivity (100 → 200 = +1 EV) |
| ASA | American standard, forerunner of ISO | same values as arithmetic ISO |
| DIN | German standard | logarithmic: +3 DIN degrees = sensitivity doubled (21° = ISO 100, 24° = ISO 200) |
| GOST | Soviet standard (ГОСТ), used on Eastern European films and light meters | values close to ISO, slightly lower (ISO 100 ≈ GOST 90) |
The full ISO value combines both notations, for example “ISO 100/21°”.
What the table is for
Section titled “What the table is for”- Old cameras and light meters: a camera or meter from the 1950s to the 1980s may be marked in DIN or GOST. The table gives the value to set for your film.
- Old or expired films: the boxes sometimes show a single scale.
- Understanding the steps: the table runs from ISO 6 to ISO 819,200 in thirds of a stop. Each row is one third of a stop, that is 1 DIN degree: three rows make one stop, so a doubled sensitivity.
Reminders about sensitivity
Section titled “Reminders about sensitivity”- A high sensitivity allows faster speeds or a smaller aperture in dim light, at the cost of more grain (film) or noise (sensor).
- Expired film loses sensitivity: it is often overexposed by one stop per decade past its date, depending on how it was stored.