Karl attended one of my workshops and in it I describe how to derive ISO or ASA empirically. So, I know that he knows how to do it, unless he was asleep in that session.
So what is being done here? Trying to determine the "actual ISO value" suggests the manufacturers can't do it for themselves. Anything we determine for ourselves is our own EI and using the ISO standard crtieria to see what figure we get for ourselves is a pointless exercise or at best purely academic. It has no value to the world at large since we already know what the manufacturers ISO is and we only use that as a starting point for our own tests to work out our personal EI.
I just don't see the value of it as a marketable excercise. For personal use by the tester or as a purely academic learning exercise for the tester then sure it has some value, but for the world at large I think not.
And any serious amateur and up will do their own testing anyway, regardless of some unverified published results from an enthusiast.
I'm not being negative here. Purely realistic.
So go ahead with the tests for your own personal satisfaction but don't expect anyone to accept them as accurate. Afterall, we all think the manufacturers can't get it right with their millions of pounds of research funding through the years, so why should we think your results will be any more accurate
Last edited by rob champagne; 12-07-2007 at 08:08 PM. Click to view previous post history.