Mon Feb 26, 2018 11:14 pm
The big issue is, the MFT focal reducers are calibrated for a 4mm sensor cover glass thickness, while the Pocket/Micro Cameras use a 2mm cover glass. This will result in slightly sift images when using a lens wide open, especially with lenses like the Sigma 18-35 Zoom. The Metabones BMPCC SB is calibrated for a 2mm sensor cover glass.
I tried using the original Metabones MFT SB, and while it worked, i had to stop my lenses down to get a sharp image. This also makes pulling focus harder without a zoom in Monitor or EVF. The .71 focal factor is based on the larger MFT sensor also, and will spill more light around the BMPCC sensor. You also get a greater focal reduction factor as I previously pointed out, 0.58 vs 0.71, which puts traditional 135mm focal lengths to S16 equivalents, like 50mm to 29mm for a pleasing head shot.
Cheers
Denny Smith
SHA Productions