I've only done 2 lenses so far, my 85mm 1.8 (which comes up with a different number, near zero, each time) and my 50mm 1.4 that won't calibrate at all.For lighting, I learned the hard way not to use CFL or Fluorescent Tubes
Lighting I think is an issue, but the mac beta says sorta weird things about iso, so who knows . . . not a lot of time on my hands
They drive FoCal nuts!