Originally Posted by
xpatUSA
May I clarify that?
Only the shutter speed and aperture directly impact the exposure of the sensor. All other forms of chicanery such as, ISO, EC, etc., affect only the combination of shutter speed and aperture, therefore ISO affects exposure indirectly.
The proof of the pudding being in that, if one sets the camera in manual at some fixed combination of shutter speed+aperture and then waggles the ISO knob around taking many shots of the same scene, the raw data (i.e. sensor exposure) will not change much, if at all.
While this is admittedly a trivial clarification and could be viewed as irrelevant, it may have some bearing on this thread's discussion.