ASA? ISO? DIN?!? What’s the Difference?

Boxes of film can have all sorts of numbers on them.  What do they mean?

Boxes of film can have all sorts of numbers on them. What does that big number on the box or canister mean?

I get a few people who ask me what the difference is between ASA and ISO, and an even more random mention of what DIN is.  All three terms are used to describe film speed or, more technically, film sensitivity.

 

Kodak Gold 200 being loaded into my Pentax K1000.

Kodak Gold 200 being loaded into my Pentax K1000.

Without going into too much detail, the higher the value, the higher the sensitivity.  Low values need more light to give a proper exposure (by using a larger aperture or a longer shutter time), while higher values need less light.

Used rolls of Kodak's Ektar 100 ready for processing.

Used rolls of Kodak’s Ektar 100 ready for processing.

Back in the 80’s when I was shooting with my father’s Olympus Trip and my Haminex point and shoot, then towards the 90’s when I learned to shoot on the Pentax K1000, ASA and DIN were more common-place terms.  ISO is newer and started becoming more used in the late 80’s.

The primary controls found on the top of the Pentax K1000 (Top to bottom from the centre of the photo): ISO and shutter speed dial, shutter trigger, film winder and exposure counter.

The primary controls found on the top of the Pentax K1000 (Top to bottom from the centre of the photo): ISO/ASA and shutter speed selector dial, shutter trigger, film winder and exposure counter.

Strangely, my K1000 used ISO on the film speed dial, while my son’s ME Super has ASA on it!  This is leading me to believe that the ME Super (this model was produced from 1980-1986) is an older camera than my trusty K1000 (this model produced from 1976-1997 – I’m speculating that mine was produced between 1987-1990.)

Going extreme...ISO 3200 to ISO 100.

Going extreme…ISO 3200 to ISO 100.

Back to the films, as you know, I have a preference to using 100 speed film because I liked to shoot outdoors.  This is what was then considered “medium speed.”  High speed films (anywhere 400 and above) were more expensive and low speed films (anywhere below 100, and yes, they went down as low as 12, though I only remember seeing a 25 speed film in the Philippines when I was a kid) were used in cameras mounted on tripods.

Remember the dial settings above?  What is the ISO of this roll of film I was removing?  *Palm to face moment*

Remember the dial settings above? What is the ISO of this roll of film I was removing? *Palm to face moment*

So I leave you with this teaser above…perhaps another post about our film follies to come, once I get around to developing this roll.

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