Robert Swier wrote:
> Quoting from the article:
> "An individual film grain can only be either black or not-black, on or
> off, exposed or not exposed."
>
> This is not true, right? It's possible to make an image brighter or
> darker on film by changing the exposure time. So, where do these
> varying levels of brightness come from if each "grain" can only be on
> or off?
From my limited knowledge I think an individual grain is either exposed
or not exposed but I believe the size of film grains varies and larger
grains are more sensitive than smaller grains. They don't all get
exposed at the same light intensity. Film grain size is also why high
ISO film looks grainy... all the grains are larger.
>
> The point about pixels being analog also isn't true, of course,
> because pixels do not have a continuous range of values. (The number
> of values they can assume is less than infinity.)
Well, I think he was really making a relative comparison. I think the
pixel itself is analog and responds linearly to the number of photons
striking it but the analog value has to be digitized on the way out.
Even if you only accept the digital output side an individual pixel may
have about 12 bits. 4096 values is a lot more "analog" than "on/off"
>
> That being said, it still might be true that it takes a clump of
> "grain" to produce a broad range of tonal values, where as a single
> pixel might be able to do the same thing.
Yes, that's exactly the point he was making.
>
> [Related note: I shot a roll of film yesterday for the first time in
> months. OM4t with the 50/3.5 macro. The E-1 stayed home. It was
> actually the first time I'd ever used the lens. What a joy! I work so
> much slower and more deliberately with film. And I don't even miss
> the histogram!]
>
>
> On 3/8/06, Chuck Norcutt <chucknorcutt@xxxxxxxxxxx> wrote:
>
>>I never have understood why low resolution digital looks so good
>>compared to film until I found this. Now it all makes sense.
>><http://www.luminous-landscape.com/essays/clumps.shtml>
>>
>>Chuck Norcutt
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