> >From: "P�l Jensen" <[EMAIL PROTECTED]>
> >
> >Low light is an area where digital cannot compete.
> >
> >P�l
> >
>
> Well, if there is one area where CCD is far superior to film, it is in the
> low light area.
> The special Kodak astronomical emulsions are almost extinct, now all major
> observatories switched to CCD.
>
That is correct. I've been trying to hunt down the article I have that gives
the response of CCD's versus film. Film is dead in the water compared to a
CCD. For a start CCD's have a linear response curve whereas film rapidly
tails off.
However, there is always a downside to things: CCD's suffer from dark
current; random electrons being generated by heat in the CCD and thus
causing noise in the picture. Astronomical use of CCD's usually requires
cooling for long exposures (although film does as well). The reason why
CCD's in digicams are kept at low ISO's is because of the dark current - not
because they are inferior in any way to film at detecting light. However, as
CCD technology improves the dark current is reduced and better SN ratio is
achieved.
That is why film's funeral has already been booked and the coffin made. :-)
doctor digi
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