I want to take the opportunity to pass on the writings of a distinguished forum member over at the BMCuser forum that really struck me as being one of the single most important lines that I have read on that forum or anywhere else in a long time. It was a true eye opener for me to grasp a highly complex subject. He writes concering the confusion often raised when trying to convert SLR camra lenses adapted to the Full Frame 35 mm format for use with Super 16 Digital Film cameras, and the use of Speed Boosters, such as that of the Metabones, to mitigate the crop factor produced by the Super 16 sCMOS sensors of cameras such as the Blackmagic Pocket Cinema Camera and Blackmagic Micro Cinema Camera from 2.88x down to 1.75x. I have taken the liberty to edit the citation and correct any typos, as well as writing out in full certain abbreviations:
Since you have a [Blackmagic] Micro S[uper] 16 [Cinema] camera, I suggest you start thinking in terms of S16 lens F[ield] O[f] V[iew]/focal lengths, and forget trying to relate it to a F[ull] F[rame] 35mm still camera, which is not a cinema camera format! Learn and embrace your S16 format. A 17.5mm lens is your normal FOV lens (same as a 50mm on a FF camera if you insist). Then 10-12mm is wide angle, 25-35 short/medium tele, with 29mm being the sweet spot portrait focal length.
The 2.88 or 1.75 is a crop factor of a FF 35mm still (DSLR) camera format has nothing to do with the actual field of vrew (FOV) of the lens on a S16 size sensor camera. This is an apples to oranges comparison, invented by the Canon/Nikon marketing to sell the original APC sensor cameras, to 35mm still film shooters. Nothing to do with Cinematography and the actual FOV of a given lens on a given Cine camera format, all of which are smaller than a still 35mm/FF DSLR cameras.
My point was to forget all of this marketing jive, and learn to use the lens focal lengths designed for the format you are shooting in. The only reason to get a speed booster, is to use any FF 35mm lenses you may already have, and get the best FOV possible from a given focal length. Or, as in your case to invest in some Cine lenses, you can use on different Cine cameras with different sensor sizes. The Speed Booster is the opposite of a tele converter, maintains the FOV on a smaller sensor camera (S16 or MFT) as that focal length would have had on a Cine standard 35mm (not S35, which is a little larger size) sensor/gate size camera.
My point was to try and think in your new format, and from a cinematographer’s perspective, not from 35mm still photography. Know what your “normal” FOV is for any given Cine format, and then make your lens choices based on that, as far a focal lengths are concerned. My advice to you, is if you are new to Cinematography and Cine type video cameras, is to keep it simple to start, and get a native MFT zoom, like the excellent Panasonic 12-35 MFT zoom, no adapter or speed booster required, and it is on sale right now at a very good price. With this small zoom, you keep the Micro’s small compact form factor, reduce the size needed for a tripod/video head, and with the zoom’s I[mage] S[tabilisation], you can do short handheld takes.
By starting out with the zoom, you can then determine which focal length lenses you like/need, and then make a lens kit buying choice. Also look at the new MFT Mini Cine lenses from Veydra, and the new SLR Magic line up (MFT Hyperprimes, their 10mm is excellent, or the larger APOs). Take “baby steps” to start, then once you have your feet on the ground, you can start running! (Denni Smith, 10-27-2016)
What he is saying concerning the Blackmagic Micro Cinema Camera also concerns the Blackmagic Pocket Cinema Camera as both cameras share the exact same 1080p sCMOS sensor, the Fairchild Imaging CIS1910. I have elsewhere written on this site that the Super 16 and 16 mm film formats effectively erase the crop factor, which is always referenced back to the full frame 35 mm still format. That was partially true (or false, depending on your outlook), so elegently explained in the citation above, as the focal lengths of the 16 mm and Super 16 formats actually are compatible with the 35 mm format, making a Super 16 50 mm lens equivalent to a 50 mm lens of the Full Frame 35 mm format in the measured focal length, but not in the Field of View as a Super 16 lens collects and focuses the light onto the Super 16 gate aperture in a much more narrow way as compared to a Full Frame 35 mm lens. This means that the Field of View of a Super 16 50 mm lens is not equivalent of the FOV of a Full Frame 35 mm lens; the 17.5 mm lens of the Super 16 is on the other hand. Confusing? Then red and re-read the citation above unti you grasp it. As an aid, look at the inserted illustration; logic dictates that the lens (and thus the focal length) has to be pushed backwards closer to the focal plane for the “cropped” sensor to exhibit the same FOV as the Full Frame sensor. Also in closing, listen to Philip Morris debunking the crop factor issue when it comes to Super 16: