The latest lens adapter from Metabones is something a little different. Not only does it allow you to attach popular DSLR lenses onto mirrorless camera systems, it enables you to gain an extra f/stop from your lens and nearly full frame focal lengths from an APS-C sensor, practically removing the focal magnification.
What this adapter is, essentially, is an inverted teleconverter. While a teleconverter increases the magnification by 1.4x or 2x, the Speed Booster has a magnification of 0.71x, allowing more of the image to fall on the sensor, which also means more light.
In practical terms placing a 50mm lens on a APS-C body with a regular adapter would give you a focal length of 75mm, while on a Micro Four Thirds body it would give you 100mm. Using the Speed Booster, you would get the equivalents of 53.25mm and 71mm respectively. This means that your old lenses can be used closer to the field of view they were designed for and is most useful when it comes to wide angle lenses. The focal magnification of even APS-C means that very wide lenses are needed to achieve a wide angle view. However, using the Speed booster would allow for more standard lenses to be used.
The inversion process means the amount of light hitting the sensor increases by a full stop, hence the name Speed Booster. This is due to the light that would normally miss the sensor being redirected by the optics.So an f/1.2 becomes f/0.9, an f/1.8 becomes f/1.2 and an f/4 lens becomes an f/2.8.
The adapter will be available initially for Canon EF and Nikon F lenses, with fittings for Sony NEX and Micro Four Thirds camera bodies.
Plans for Leica R, Contax C/Y, Contrex and Alpha lens adapters, and Fujifilm X mount fittings are underway. Due to the reduction of the image size using the adapter, a full frame lens is required to fully cover an APS-C sensor. However, for Micro Four Thirds sensors, a digital only (EF-S or DX) lens can be used.
The adapter features a removable tripod mount and in the Canon EF version, allows electronic iris control, AF and VR functionality. The unit price and availability are still to be confirmed. For more information visit www.metabones.com
Maximum input aperture: f/1.26
Maximum output aperture: f/0.90
Lens elements/groups: 4/4
Objective lens mounts: Canon-EF, Nikon-F (Leica-R, Contax C/Y, Contarex and Alpa planned)
Capabilities, Canon-EF version: Electronic iris control, AF and VR
Capabilities, Nikon-F version: Manual iris control of G type lenses
Camera mounts: Sony NEX, Micro Four Thirds, (Fuifilm X planned)
Length reduction (Sony NEX, version): 4.16mm
Length reduction (Micro Four Thirds version): 6.17mm
Dimensions Sony NEX version (diameter x length): 69mm x 27mm (with tripod mount removed)
Weight Sony NEX version: 194 grams
Tripod mount: Removable type with Arca Swiss compatibility