Yesterday, Metabones and Caldwell Photography introduced a revolutionary product which has the potential of changing the market of mirrorless cameras. Their new Speed Booster mount adapters widen the field-of-view and maximum aperture of lenses!
How It works?
Unlike a typical mount-adapter, the Speed Booster includes optical lenses to take a large image circle and make it smaller, 0.71X smaller to be exact, thus acting as a wide-angle lens would. Since the image circle shrinks, while the aperture opening remains the same size, it makes the F-stop one full stop brighter.
For the uninitiated, the F-stop is measured as the ratio between the focal-length and the aperture diameter. So a 100mm lens with a 50mm maximum aperture is F/2 since 100 / 50 = 2. With the Speed Booster, the focal-length of the same lens becomes 71mm since 100 x 0.71 = 71. The aperture though stays 50mm wide, so it is now measured as F/1.4 since 71 / 50 = 1.4.
Normally we see teleconverters do exactly the opposite. They cannot widen the field of view because they are designed for a camera and lens that match in terms of image circle and sensor-size. The Speed Booster however takes advantage of the fact that mirrorless cameras often have smaller sensors than DSLRs, so they usually require a smaller image circle than what the lens provides.
With a 0.71X multiplication factor, a full-frame lens gets the same field-of-view as it would on a full-frame camera when mounted on a mirrorless camera with an APS-C sensor. Since APS-C sensors have a 1.5X crop-factor which multiplied by 0.71X gives 1.065 which is close enough to 1 for all intents and purposes. For Micro Four-Thirds cameras with their 2X crop-factor, the multiplier becomes 1.42X with the speed booster.
Why This Is Huge?
Mirrorless cameras have been growing faster than any other type of digital cameras. However, they have been growing much faster at the low-end than the high-end because professional photographers need a wide variety of lenses.
Most mirrorless systems were launched along with adapters to support the same manufacturer’s lineup of DSLR lenses but this left a significant problem for wide-angle lenses which no longer stayed wide-angle.
Fuji, one of the last entrants in the mirrorless markets, particularly started by offering a high-end product with a limited selection of prime lenses, 3 to be exact. This has been expanded with an extra prime and one short zoom. Not only that, Fuji does not currently produce DSLRs and never has with its own mount. Their highly-acclaimed DSLRs used Nikon mounts.
Metabones announced that the Speed Booster is planned for Fuji X-Mount but not in production yet. This makes sense for Metabones because Fuji has not sold that many mirrorless cameras yet. However, Fuji has the most to gain from such an adapter.
Adapters for Sony NEX and Micro Four-Thirds camera mounts are being initially produced. Each of these adapters will be available in versions for Canon or Nikon lens mounts. Future adapters will support Leica-R, Contax C/Y, Contarex and Alpa lenses.
This puts the Sony NEX system in an excellent position. It already accepts full-frame Alpha lenses with an adaptor and now the Speed Booster lets these lenses recover their original field-of-view.
When Can You Get One?
Very soon actually. The initial versions are scheduled to ship this month with a price of $599 USD plus shipping, applicable taxes and duty.
News via Photo Rumors.