In article , nap says...
http://www.photonstophotos.net/Chart...M1%20Mark%20II

ISO 83 measured at both ISO 64 and ISO 200.

But in reality the exposure time at ISO 64 is three times the exposure
time at ISO 200. That diagram contains wrong data.
--
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