There's more than one way to get a lens on a camera it shouldn't naturally fit, particularly when adaptation has to go beyond mere lens mount disparity and extends all the way to major sensor size differences. Of course, in approximately none such case does the adapter getting the job done actually widen field of view, improve clarity and sharpness, and increase exposure levels by up to one full stop. In fact, to expect as much (and all in one device) would seem to equate to madness -- especially if such a device supports electronic lens control. This is not the short and skinny of the new Tom Cruise sci-fi/action film, but that of the Metabones Speed Booster. The adapter not only mounts your Canon full frame 50mm f/1.8 lens, for instance, to your Sony FS100 -- but also turns it into a sharper 35mm f/1.2 in the process.
Despite being called the Speed Booster, this device does a lot impressive optical and electronic things to the benefit of any attempting to bridge the gap between, say, a strong Canon stills lens collection and the modern Super35-sized video cameras being proliferated by Sony. Metabones is also offering several other variations and combinations on their site, including adaptation from Leica R lenses to Fuji X cameras. Below is a video review from Bryant Naro which accompanies his writeup on the Speed Booster, which also has this to say:
Turns out that they’ve designed an integrated ‘focal reducer’ to their NEX lens mount adapter. It’s basically a reverse teleconverter. What does this mean? Well, like they say, it truly does increase the speed of the lens, technically. Why now and not… since the beginning of time? Well, a lot of things have changed lately that let this technique exist. Metabones notes the 18mm flange distance in the FS100 (distance from the mount to the sensor) is much shorter than typical cinema cameras that came before it. Also, using EF lenses meant for 35mm still photography will work just fine with the .71% adjustment, considering the FS100′s super35mm sensor.
This is a great visual breakdown of what's going on with the Speed Booster from the tremendous post by Philip Bloom and James Miller:
The illustration makes it a bit more clear as to how this process could actually be improving the perceived sharpness and clarity of a lens -- in the same way downscaling to 2K from 4K acquisition improves apparent quality by burying 'aberrations' such as noise, squeezing a physically larger image to fit a smaller sensor size masks what imperfections the lens may actually produce. The byproduct of which is this: the effective 35mm lens the Speed Booster turns your full frame 50mm into could actually perform better than the 35mm designed for your APS-C camera. To boot, that same squeeze-down means more light gets crammed into that smaller image, too -- after all, light is all a lens image is -- and more of it getting shrunk to your sensor means, well, a brighter picture.
I'm less excited overall by the electronic control support, but this is doubtlessly a serious consideration in convenience for a majority of shooters -- if you're with me, though, keep in mind you can also match any manual lens of the proper mount to its Speed Boosting counterpart, which is super useful in and of itself. The notion that will inevitably come to mind (and already has in Philip's post) is how this technology could benefit systems that may otherwise suffer from excessive sensor crop, such as the Blackmagic Cinema Camera. Mr. Bloom points out an upcoming Micro 4/3 Speed Booster, which -- in conjunction with an 'active' M43 mount -- would do wonders for counteracting some of the field of view truncation going on and allow the aperture control utilized by the BMCC. That said, I'd just as soon mount a manual lens -- the main thing for me is the widening effect the Speed Booster could accomplish for BMCC shooting.
I've read a few things denoting the lack of compatibility with the Sony VG900, which electronically is explicitly true -- even with that camera's full frame sensor, though, Speed Booster could play by combining the camera's crop mode with manual lenses. The usefulness of these adapters is, like anything else, determined largely by the gear you already own or find yourself using often. The exciting possibilities opened up by this technology, however, are undeniable. The Canon EF lens to Sony NEX Speed Booster sells for $600.
What do you guys think?