On Oct 31, 8:00 pm, Peter Irwin <pir...@[EMAIL PROTECTED]
> wrote:
> UC <uraniumcommit...@[EMAIL PROTECTED]
> wrote:
>
> > It is my opinion, and that of many others, that the 'new' ASA speed
> > sytem introduced in 1959 gives numbers that are too high, by about 2/3
> > stop.
>
> I think the primary reason for this is that the question
> you want the ISO rating to answer is a different question
> from the one it was designed to answer.
>
> The question the speed rating is designed to answer
> is "what is the minimum exposure required to produce
> a negative from which a print judged to be 'excellent'
> can be made?"
>
> The question you probably want answered may be
> something like "What exposure meter setting will
> consistently give negatives that are easy to print
> well?"
>
> The answer to the second question is going to generally
> be a lower exposure index than the ISO standard.
>
> Peter.
> --
> pir...@[EMAIL PROTECTED]
I don't think the shadow contrast is as good at ISO as it is at
about 2/3 ISO. This is based on many thousands of negatives.
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