> Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx> wrote:
>
> That's interesting. DPReview has been reporting actual ISO test results
>
> for a long time. DXO says the Canon 5D's ISO 100 is actually 92.
> DPreview reported it as 125. And, of course, Canons says it's 100.
> Who's right? I doesn't make any difference until I have to get out the
> external meter for flash.
>
A couple of points:
What was the actual film speed of Kodak Portra 400 ?
Would anyone really notice if it was 380 or 420 ?
How much variation is there from batch to batch ?
Is there an actual ISO standard for measuring the "speed" of a digital camera ?
There is for film, but since the "characteristic curve" (from which the film
speed is measured) is different for film and digital I doubt you can just
directly apply the film standard to a digital sensor.
...Wayne
Wayne Harridge
http://lrh.structuregraphs.com
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