Film Speed ASA, DIN, and ISO by Michael Leyba

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TERMS:

ASA:
There is a term for film speed that photographers have used for many years. It is called ASA. It stands for the American Standards Association. It was established to develop a standard by which films could be compared as to their rating for light sensitivity. It is also related to digital sensors as well. Camera manufacturers calibrate the cameras based on the ASA standards. A digital camera can have a large range of ASA speeds. For instance, my Canon 30D camera has a range from ASA 100-3200.

DIN:
The German equivalent to ASA is called, DIN for Deutsches Institut für Normung.

ISO:
There is also an ISO for International Organization for Standardization and most digital cameras refer to this as their film speed setting.

GOST:
The Russians had their own standard for film speed known as GOST.

NOSTALGIA:
I miss a film speed that used be available. Many remember it fondly. It was ASA 25. It was available on Kodachrome Slide Film. This film speed was very low, but had great quality. The film seemed to last much longer than Ectachrome slide film. The chemical processing was different than Ectachrome slide film.

I would love to have a setting of 25 ASA for my Canon camera. The reason is that it is great for use in bright light. I would rather have this setting than use a neutral density filter if it is overall slow speed I would like to use and I don’t want to overexpose the photograph.

EXAMPLES:

For shooting in low light I would use the lowest ISO available that will get you the highest shutter speed to get a clear image. The higher the ISO the grainier or more noise will be in the image. I tend to want to shoot with ISO 400 for low light. When I go above that the quality of the image is degraded. It is worse of low lighting situations. If is a must then I use higher ISO settings.

For shooting in bright light I would use the lowest ISO for sure. This would mean in most cameras of ISO 100 setting.

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