In article , Floyd L. Davidson says...

Alfred Molon wrote:
Once again: explain why at ISO 64 the exposure time is THREE times the
exposure time at ISO 200.

The DXOMark site you are referring to claims that both at ISO 64 and ISO
200 the real ISO is 83.

But if the real ISOs at ISO 64 and 200 really both were 83, the exposure
times should be the same. They are not, so DXOMark and you are wrong.

You don't understand sensor characteristics, ISO, or
exposure; and should not be saying others are wrong.

DXOMark is not wrong.

Consider that the design target for maximum output from
a sensor, in terms of linearity, may not be the actual
maximum output. Also consider that a "correct" exposure
level might be 2.7 fstops below whatever is chosen as
the "maximum output", or it might be 1.3 fstops! All of
that is totally independent of when whites actually do
clip, which is a function of the ADC, not the sensor.

And all of that makes what you believe to be how it
works just a little bit the other side of a fantasy too.

Floyd,

please explain why at ISO 64 the exposure time is three times the
exposure time at ISO 200. DXOMark claims that at both ISO settings the
true ISO is 83.
--
Alfred Molon

Olympus E-series DSLRs and micro 4/3 forum at
http://tech.groups.yahoo.com/group/MyOlympus/
http://myolympus.org/ photo sharing site