Last year Metabones came out of nowhere with the Speed Booster, a product that seems too good to be true until you look at the results. While it does have its faults, your lenses do really become faster and wider, giving you a lot more options for mirrorless cameras that have smaller than full-frame sensors. We've heard rumors about a Metabones Canon EF to Micro 4/3 Speed Booster that would give full iris control on MFT cameras (we've already got the Nikon version which is all-manual), but nothing was concrete until now. The first product out of the gate is for the Blackmagic Pocket, which is going to make the camera that much more usable with full-frame lenses.
We've got a video from James Miller showing off the Speed Booster on the Pocket:
And here is a little bit from the post on what this Speed Booster does:
The new 0.58x EF-BMPCC Active Speed Booster reduces the crop factor of the BMPCC from 2.88x to 1.75x, and produces the largest aperture optics currently available, with a maximum output aperture of f/0.74. For example, a 50mm f/1.2 now becomes a 29mm f/0.74 (i.e, by using 50mm lens, the actual focal length in BMPCC is 29mm x 3.02 = 87.58mm), and the Sigma 18-35mm f/1.8 becomes the world’s fastest zoom lens at 10.5-20.3mm f/1.0 with stunningly sharp performance. (i.e, by using 18-35mm lens, the actual focal length in BMPCC is from (10.5mm x 3.02 = 31.71mm) to (20.3mm x 3.02 = 61.31mm).
He also said this if you try to mount the adapter on the GH4:
The GH4 will display “Lens attachment failed. Please make sure the lens is attached correctly”. There is also an etched a warning “For use only with BMPCC” on the BMPCC Speed Booster housing.
This is big news for the Pocket camera. While there are a bunch of compatible MFT lenses, and a Speed Booster for Nikon & Leica R lenses already available, the Canon mount is more popular for video shooters, and you also can adapt Nikon lenses to the Canon EF Speed Booster very easily. With this adapter, not only do you get aperture control for the Canon lenses, but you also get image stabilization.
There are a few downsides at the moment, however. The first one is the $660 price tag, which comes in at around 2/3 the price of the camera itself. While they are working on versions for regular MFT cameras like the GH4, this one is made only for the Pocket, and should not be mounted on other MFT cameras since it isn't made to cover the full sensor and the rear element sticks out quite a bit. The other downside is related to EF-S lenses:
The EF-S mount has the same 44mm flange distance as the EF-mount, but the rear of the lens is allowed to protrude a few mm further into the mount aperture and possibly hitting the optics of the Speed Booster. You may be able to mount some EF-S lenses by removing the protective ring protruding from the rear of the EF-S lens.
Also, an adapter for the 2.5K Blackmagic is unlikely since it has a dumb MFT mount, so it can't send power to control Canon lenses (though maybe they will engineer a powered adapter at some point in the future like the Redrock MFT adapter).
Even with the price this will likely be a popular item, and I know many have been waiting patiently for this exact product. Though this Pocket Speed Booster is not really made to be mounted on other cameras, Andrew Reid over at EOSHD did just that with a prototype on the Panasonic GH4 shooting in 4K, and got some interesting results that made his lenses nearly full-frame on that camera (though he did have some issues):
The Pocket Speed Booster should start shipping by the end of this month over on the Metabones site. You'll be able to find it at the link below when it becomes available.