I see said the blind man!

Thanks for your great clarification for this newbie! 

Referring to "slow" and "fast" film isn't erroneous. For the same given aperture and light level, a "fast" film takes less time to form a proper exposure on the film. Thus a faster shutter speed is used.

It's less misleading than talking about "fast" lenses (eg f:1.4) because the film actually did react faster to light, as well as leading to a faster shutter speed.

Sure, in digital, it's not actually doing anything faster. But if you can call a lens fast because it allows faster shutter speeds, reffering to a faster ISO sensitivity isn't any more innacurate. It would sound odd to me though.

Down in the fifties indeed!  What about DIN, Weston and Scheiner speed ratings?

It seems you can almost equate digital noise with grain on film.

A very interesting article- thank you.

Robert.

Robert:

DIN (Deutsches Institut für Normung - German Institute for Standardisation) is fairly obselete.

In modern times globalisation has led to international standards that wouldn't have existed when the Germans, for example, made a film speed standardisation back in 19-sumthingorother...

Plus, it's a very different standard:

DIN        ISO             ASA

21°        100/21°      100

24°        200/24°      200

27°        400/27°      400

30°        800/30°      800

33°        1600/33°    1600

It does kinda make sense because of the 1/3rd stops you have with ISO 125 and ISO 160 for example would be DIN 22° and DIN 23° respectively...

By the way - as you can see from my table...ISO tends to never be listed properly...officially it should be ISO/DIN....but over time this has been phased out - and the American standard has dominated and essentially driven the way in which ISO is termed. 

There are still some sorts overlaps however - in America for example you can but 5x7" sheet film, whilst in Germany the standard is a 13x18cm sheet - which is a couple of millimetres different in size....may seem insignificant, but means that the two sizes need entirely different sized film holders....  FujiFilm still make 13x18cm Velvia 100...but there's no such existing size in 5x7" (I would imagine this will phase out soon though...)

As for (Edward) Weston...he made his standardisation before ASA / ISO were around..... That was around 1930... I don't know how his system worked, but it was in association with a light meter system that he released - which would have worked on the basis of his standardisation.

I don't know anything about Schneider-specific ratings...but would be curious. 

Blimey that was a big rant....hope this may have been of some use to you (all?)...

Also...you may be interested to know that there were other standards:

Russia had a GOST standard...this was essentially 90% of ASA...So ISO 100 was GOST 90.

There was a British Standard too (BS)....either it was dropped given the impact of such an acronym (hah!)....or, given that it was exactly the same index as ASA it kinda got adsorbed into that!

Sometimes I forget how deep things can go....these days you just click your ISO settings dial on your digi without thinking of the way things have formulated over time.  This is before we even begin to talk about chemical film development...

If you delve into the history of film sensitivity measurement, or just cheat and go to Wikipedia, there's a whole world of standards. If you bought a lightmeter in the 1950s, there were more film speed settings than there were exposure values. DIN/ASA/GOST... and if you go back still further, you can find devices that record H&D values.