I've been reading about the new Metabones Speed Boost adapter announced recently. Looks like a great product. I wish Metabones or some other lens adapter manufacturer would make a lens adapter that had built-in neutral density filters for cameras like the BMCC or Sony FS100. The lack of built-in ND filters is what has kept me from purchasing a BMCC.
I agree that it is a very cool adapter. But an adapter that had ND filters as you desire, while it would be cool and very helpful, would probably be more expensive than just buying a Tiffen 4x4 or 4x5.65 glass kit. Also bare in mind that the ND's in the cameras are rotating wheels. You would be talking about needing to have a large attachment coming off of the adapter to house that wheel and advance it into place. Very cumbersome indeed. But with the availability of even screw ons, I would not let a lack of ND filters be a reason for not buying the BMCC if you like the look of the camera.
However you're right, if the adapter is as good as Philip Bloom seems to say, then it can be very helpful and offer a lot of real flexibility. Personally though, I like the look of Super35. I like the DOF that it gives and I am used to the focal lengths on it. Essentially the adapter gives full frame on APS-C, which in film terms is basically vistavision. I think that something many people need to remember is that just the ability to have full frame looks doesn't mean that you should every time. Full frame is not actually "cinematic" in the way we think of the term. All said and done though, I am excited for the adapter as that does give us another tool in the arsenal which is always good no matter how you spin it.
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