I knew what ASA was, was temporarily confused when it changed to ISO, but still basically got it in the film era. But I have to confess to only a conceptual understanding of digital ISO, the more I read the more it seems to be a combination of the ACTUAL sensitivity of the sensor and various electronic tricks played with gain and stuff that I really don't get. I saw Andy Westlake explain it in pretty good detail over on DPreview once or twice and SORT of got it while I was reading it, but not nearly enough to really GET it, let along ever be able to explain it to anyone else. Seems like a very different "thing" than in the film days, but is trying to get at the same basic function. And I'm just gonna have to be satisfied with that. Some cameras seem to work well at high ISO and some don't and that's ultimately what I need to know.David,
Any old school shooter knows what ASA is.
They know what ISO is also but they don't like it.