Basically, to make a film 'faster' you capture phonons from a larger area. Or the other way around, film that can resolve very fine details needs a lot of light

Basically, to make a film 'faster' you capture phonons from a larger area. Or the other way around, film that can resolve very fine details needs a lot of light. Film has a built-in low pass filter. Typically 'sampling' in film is random enough that you can capture very fine detail if the contrast is high enough. It behaves quite differently from digital sampling techiques. For this reason, you want to scan film at a very high resolution. But that doesn't mean that the image actually contains a huge of informaion.