This evaluation by the Diallo & Butler duo focuses more on stills photography rather than video, and this is why we like it. Nice explanation of the focal reducer technology, and with/without the SpeedBooster adapter side-by-side pics. At the DPreview bench was the only auto-focusing version of the adapter, the NEX to EF lens version, but as the reviewers found out, the AF performance is not to be taken too seriously:
"There's a lot to be excited about with a product that so transforms lens behavior and addresses such a long-standing issue for photographers who long for the wide-angle and light-gathering performance of their older full frame lenses on their newer APS-C body. Image quality is very impressive, with results that compare exceptionally well against a full frame sensor. You do pay a small price in terms of corner softness and CA.
Metabones and Caldwell Photographic introduce Speed Booster
Petersburg, VA, USA, January 14, 2013 - Metabones® and Caldwell Photographic jointly announce a revolutionary accessory called Speed Booster™, which mounts between a mirrorless camera and a SLR lens. It increases maximum aperture by 1 stop (hence its name), increases MTF and has a focal length multiplier of 0.71x. For example, the Canon EF 85mm f/1.2L II lens becomes a 59mm f/0.9 lens on a Sony NEX camera, with increased sharpness. The faster F-stop allows for shallow depth-of-field and a lower ISO setting for decreased noise. . . . read more
No longer the stuff of rumors, here's the E-M5 straight from the horse's mouth:
We got some highlights in case the file goes away, but hey, the whole document is worthy of a read. Especially for micro 4/3 camera owners :) Check out the interesting section 17 about the usage of a similar technique by Stanley Kubrick during the shooting of Barry Lyndon.
The Speed Booster – a New Type of Optical Attachement for Increasing the Speed of Photographic Lenses
Brian Caldwell, Caldwell Photographic Inc.
and Wilfried Bittner, WB Design
1) Introduction . . . read more