I have had suspicions too but still I don’t get how it’s possible to fudge
ISO, either the camera measures the EV level accurately and sets the three variables accordingly or it doesn’t. If it doesn’t why wouldn’t clinical tests reveal that? I assume test facilities like DXO aren’t asleep at the wheel and conduct tests with a level playing field, surely they would pick up oddments like
ISO’s not being accurately stated by large amounts.
Their test results graph shows that apart from the D600’s ISO50 and ISO100 both being slightly less than ISO100 and the A900’s ISO100 being above that mark by about 1/3rd the A900 and D600 level peg with one another until the limit of the A900’s reach, all the measured
ISO’s from both being slightly less than what it should be but looks like about 1/3rd stop so, i.e. not very much, according to DXO’s test anyway.
http://www.dxomark.com/index.php/Camera ... and2)/Sony
This has nothing to do with the chroma noise comparison between the two though, it’s just the accuracy of the metering and settings at an equal EV level, but the overall score difference between the two, part of which includes dynamic range etc. is quite a different story.
Greg