William Robb writes:
> I do have a question about film to digital
> comparisons. What is the comparative image depth
> of film to digital capture? I know the digital
> guys talk about 36 bit depth, but how does that
> tranlate to the capture depth of a long scale
> film such as Portra?
> Is 12 bits per colour the equivalent of 12 stops
> of tonal range?
Not necessarily. Each bit might not represent a doubling of the actual light
intensity, even though it will represent a doubling of signal out of the CCD's
analogue electronics.
12 bits will represent a range of 4096 levels (per colour). The important part
is how the range is scaled. Those 4096 levels might represent a 1-stop tonal
range with _heaps_ of tonal detail within that range. Which is great if your
lighting is flat. But when the sun comes out it'd respond like lith film :)
In reality there's a bit of a tradeoff between tonal range and tonal detail, within
the limits of the CCD (dynamic range, linearity and noise).
Cheers,
- Dave
David A. Mann, B.E. (Elec)
http://www.digistar.com/~dmann/
"Why is it that if an adult behaves like a child they lock him up,
while children are allowed to run free on the streets?" -- Garfield
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