German film speed standard — logarithmic scale where +3 DIN doubles light sensitivity. Superseded by ISO but still used on legacy stock and equipment.
Anyone working with archival footage or classic cameras will inevitably encounter the DIN scale — a logarithmic sensitivity standard that was long the norm, especially in Europe. Unlike the linear ASA scale, the actual light sensitivity of the film doubles with every 3 DIN point increase. This means: DIN 18 to DIN 21 is not just a small increase, but a doubling of film sensitivity. This logarithmic logic was practical for camera manufacturers — they could stagger aperture rings and shutter speeds more elegantly.
In practice, you primarily need DIN values when working with archival material or using old Arriflex cameras and Bolex devices. Most of these cameras still have DIN markings on the aperture ring or the film speed dial. Early light meters — especially analog models from the 1960s and 70s — also display DIN values. For example, someone working with a classic Gossen meter on set needs to have the conversion in mind: DIN 21 roughly corresponds to ISO 100, DIN 24 corresponds to ISO 200. The difference lies in the calculation methodology — ISO later combined both standards (ASA + DIN) but prefers the linear ASA logic as its basis.
The practical sticking point arises when mixing materials. If you shoot a scene with modern digital cameras (which work internally with ISO) and then want to insert archival footage or Super 8 material described in DIN, you must consistently convert the values. A common mistake is assuming DIN and ASA are directly equivalent. They are not. DIN 21 ≠ ASA 21, but rather ASA 100. This confusion leads to exposure errors, especially when calibrating old light meters or color matching Super 8 material with modern digital cameras.
Today, DIN is effectively obsolete — ISO has prevailed worldwide and standardized the norm. Nevertheless, in archives, during restorations, and when working with classic film material, you cannot avoid understanding the scale. Some documentary filmmakers and found footage artists consciously work with older materials and their original designations — in such cases, understanding DIN is not just cultural knowledge, but a practical tool.