Sean van Berlo wrote:Both work, however the 0.64x only works with full-frame lenses (but gives you a larger magnification and more light) whereas the 0.71x also works with aps-lenses...
Sean, there may be some confusion on the suitability of the focal reducers using the wider dimension of sensor on the BMPCC4K. People’s impressions of the focal reducers’s suitable taking lens may have been formed by their use on the BMCC or original BMPCC. But those sensors are significantly smaller. Here’s the current math normalized to the horizontal ‘crop factor’ which does come in handy for such quick comparisons. Comparing the sensor diagonal would be a little more accurate, but I don’t think the results differ.
mFT lenses suit cameras with a sensor crop factor around 2x crop
APS-C EF-S lenses are designed for sensors with a crop factor of about 1.6x
APS-C DX lenses are designed for sensors with a crop factor of about 1.53x
Super 35 lenses are designed for sensors with a crop factor of 1.44x
APS-H lenses suit cameras with a sensor crop factor around 1.2-1.3x (I forget).
URSA Mini 4.6K sensor has a crop of about 1.42x
Super 35 24.9mm sensor has a crop about 1.45x
BMPCC4K 18.96mm sensor has a crop of 1.9x
mFT traditional camera’s 17.3mm crop is 2.08x
BMCC has a crop of 2.28x
BMPCC has a crop of 2.88x
Ultra 0.71x reducer shooting open gate:
1.9x0.71x = 1.35x full frame (or APS-H) required
2.08x0.71x = 1.48x Super 35 or greater work
2.28x0.71x = 1.62x APS-C or greater
2.88x0.71x = 2.04x APS-C or greater
XL 0.64x reducer shooting open gate:
1.9x0.64x = 1.22x full frame required
2.08x0.64x = 1.33x full frame (or APS-H) required
2.28x0.64x = 1.46x Super 35 or greater
2.88x0.64x = 1.84x so APS-C or greater
0.5x reducer (modify Pentax version):
1.9x0.5x = 0.95x VistaVision required;
some full frame may work such as Zeiss CP2/CP3 and SLR Magic APO.
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