Understanding the DIN Number on Photographic Film
The DIN number is a logarithmic measurement that indicates the sensitivity of photographic film to light. This system of measurement was once widely used but has been largely replaced by the more modern ISO system. In this article, we will explore what the DIN number means, how it relates to film sensitivity, and its historical significance.
What is the DIN Number?
The DIN number, short for the Deutsches Institut fuer Normung (German Institute for Standardization), is a measure of a film's light-sensitivity. Typically expressed as a whole number, the DIN number roughly corresponds to the film's sensitivity to light, with a higher number indicating higher light sensitivity. For instance, a film rated at DIN 100 is less sensitive to light compared to a film rated at DIN 200.
Understanding the Logarithmic Scale
The DIN scale is logarithmic, meaning that each increase of 3 in the DIN value results in a doubling of sensitivity to light. Conversely, each decrease of 3 in the DIN value halves the light sensitivity. This logarithmic relationship allows photographers to easily calculate the film's performance under varying lighting conditions.
Historical Context and Usage
Photographic film used to be rated using the ASA (American Standards Association) and DIN systems. The ASA system was commonly used in the Americas, while the DIN system was prevalent in Europe. Over time, the ISO (International Organization for Standardization) system became the standard, replacing both ASA and DIN for its simplicity and widespread recognition.
Transition from DIN to ISO
With the advent of the ISO system, both ASA and DIN were abandoned. ISO provides a more modern and universally accepted system for film speed. Many contemporary film packaging now displays both ISO and DIN numbers to accommodate both the traditional and modern systems. In practical terms, an increase of 3 degrees on the DIN scale equates to a doubling of the film speed.
Practical Application and Age of Film
Today, if you come across film with a DIN rating, it is likely to be quite old, possibly dating back to the mid-20th century. This is because the ISO system became predominant sometime during the latter half of the 20th century. DIN numbers are an archaic measurement and are primarily of historical interest or used in specialized applications.
Modern Camera Models and DIN Number
It is important to note that modern camera models may still display the DIN number for historical or technical reasons. For users of older analog or film cameras, both ASA and DIN numbers might be listed for available film speeds. This mixed display reflects the transition period between the DIN and ISO systems.
For photographers who are interested in using DIN-rated film, it is crucial to understand the film's light sensitivity and how it interacts with different lighting conditions. This understanding can help in achieving the desired exposure and quality in the final photograph.
Conclusion: The DIN number, though an increasingly obsolete standard, remains a fascinating and useful aspect of photographic history. For enthusiasts and vintage film users, understanding DIN can enhance their appreciation of early photographic techniques and the evolution of film technology.