Difference in 100 vs. 200 ISO.

Alan Browne wrote:
Søren Reinke wrote:

Most film chip's are ISO 100 rated from the factory everything else is
pure amplification.


not quite. Each fab method results in a sensitivity that lies somewhere
in the region of 50 - 200, most sensors lie somewhere in the 100 - 200
range. It doesn't "land" on a nice round number.

I should add that it is not "pure amplification" as that does not exist
in the real world. There is analog amplification at the A/D level, and
then for the higher ISO's (800 or 1600 and up) digital amplification.

Further, there is an ISO variance between various camera models of
down/upwards of 2/3 of a stop.

Cheers,
Alan

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Greg "_" wrote:


I would look at the noise level, does it equate to an equal value for a
film exposure? If not then perhaps film is the best choice for a given
output size. I find 200 asa rather smooth but problematic in terms of
opening shadow areas

Why so? (opening shaddow areas) (or are you referring to slide film?)


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In article ,
Alan Browne wrote:

Greg "_" wrote:


I would look at the noise level, does it equate to an equal value for a
film exposure? If not then perhaps film is the best choice for a given
output size. I find 200 asa rather smooth but problematic in terms of
opening shadow areas

Why so? (opening shaddow areas) (or are you referring to slide film?)

Well does it not stand to reason the noise level at a given ISO should
be on par? I know I want equivalent exposures to match each other in
terms of the noise (At the very least- and if they don't I would use the
best tool for the job).
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