July 17th, 2012, 12:52 AM
So here's my quick and dirty experiment. Two cameras side by side. The same type of lens on both, Pentax 50mm F1.4. To make sure the lenses were the same, I checked it again after swapping the lenses. The results were consistent. I set both cameras to ISO 200 and both aperatures to F1.4. Both were set to AWB. I then let each camera meter out the shutter speed. The subject was a white sheet of paper uniformly lit and filling the entire field of view. I took 3 sets of shots. Low, mid and high illumination.
GF2, low illumination.
NEX, low illumination.
GF2, mid illumination.
NEX, mid illumination.
GF2, high illumination.
NEX, high illuminaton.
Theoretically, the shutter speed should have been the same for each set. For low illumination that was indeed the case. For the others, they weren't.
In this case, I fixed the variables except for shutter speed. That was allowed to vary and it did. If the shutter speed and aperature were fixed, then the ISO would have varied. As the OP says he has witnessed.
I may have messed up somewhere since this was done quickly in a few minutes. I can't think of anything but if you spot something, please let me know.
Last edited by lenshoarder; July 17th, 2012 at 12:57 AM.