Metabones Speed Booster adapters available for Micro Four Thirds mounts in April

Earlier this year, lens mount adapter manufacturer Metabones and Caldwell Photographic announced a product that sounded too good to be true. The Metabones Speed Booster would not only allow you to mount a full frame lens on a smaller sensor, but also reduce the effective crop factor, and add a full stop of light. But the months since the announcement of the original Canon EF to Sony NEX adapter have shown that not only is this not vaporware, but it does exactly what it promises to do — and does it well.

The Canon to Sony Metabones Speed Booster adapters went on sale in January for $599 and have garnered some positive press. (Though there are currently some supply issues with the original adapters, which you can no longer purchase at the Metabones site.) Now it looks like the Micro Four Thirds versions of the adapters are coming in April.

Micro Four Thirds shooters have Nikon, Leica R, Contax C/Y, Contarex, ALPA and Rollei adapters from Metabones to look forward to, as well as Canon EF (but not EF-S) versions in the further future. That joins the stable of already available Metabones converters for Fuji X and Sony NEX cameras.

Perhaps the most surprising result of this product is that it isn't some mediocre tube with poor optics. In fact, the initial crop of reviews have been encouraging. DPReview, EOSHD, Philip Bloom, and Roger Cicala of LensRentals have all tested it with positive results.

The adapter works essentially in the opposite manner to a tele-extender. It focuses the light circle of a lens down into a smaller area, squeezing a full frame field of view into a cropped sensor. This not only means that you have less of a crop factor, so wider lenses, but also that the concentrated light gives you the equivalent of a full f-stop of brightness. If you want a more technical explanation, both the DPReview and LensRentals reviews we linked above delve into the optics further, and there is an official white paper from Metabones.

I can imagine this adapter being of particular interest to Micro Four Thirds shooters, as the 2x crop factor of those smaller image sensors makes it more difficult to get a wide-angle lens effect. The upcoming Metabones adapter will change it to an effective 1.4x crop, which is close to that of APS-C.

The Metabones Speed Booster adapter don't come cheap, which is hardly surprising given the considerable engineering feat they represent, and will set you back $400-$600. However, apparently a Chinese company called Mitakon is working on a more affordable alternative, though you'll be hard pressed to match the optics of the one Metabones has created.

(Via 4/3 Rumors)