DIN

Technical Details

The DIN scale is based on logarithmic values: 15° DIN = ISO 25, 18° DIN = ISO 50, 21° DIN = ISO 100, 24° DIN = ISO 200, 27° DIN = ISO 400. The measurement was taken at a density of 0.1 above fog plus base density. Professional film emulsions like Kodak Vision3 50D correspond to 18° DIN, while high-sensitivity materials like Kodak Vision3 500T are at 27° DIN. The temperature dependency is ±1/3° DIN per 10°C deviation from a 20°C development temperature.

History & Development

The German Institute for Standardization (Deutsches Institut für Normung) established the DIN standard in 1934 as an alternative to the American ASA system. Ferdinand Hurter and Vero Charles Driffield had already laid the sensitometric groundwork in 1890. In 1974, the international ISO standard emerged from DIN and ASA, unifying both systems. Eastman Kodak and AGFA-Gevaert used both DIN and ASA markings on their film cans in parallel until the 1980s, before ISO took over completely.

Practical Use in Film

Cinematographer Gordon Willis deliberately worked with underexposed 18° DIN emulsions on "The Godfather" (1972) to create its characteristic darkness. German productions in the 1960s and 1970s primarily calculated exposure based on DIN values. ARRI light meters like the Ultra Spot displayed both scales in parallel. The precise logarithmic scaling facilitated exposure corrections: +3° DIN always meant one stop less exposure for the same lighting.

Comparison & Alternatives

While ASA/ISO increase linearly (100, 200, 400), DIN follows logarithmic perception (21°, 24°, 27°). The conversion is: ISO = 2^((DIN-1)/10) × 0.8. Modern digital sensors exclusively use ISO values, with cameras like the ARRI Alexa Mini classifying their native ISO 800 as a historical 27° DIN. Light meters from Gossen or Sekonic still offer DIN conversion today for vintage equipment and historical film restorations.