Metabones has released a new Speed Booster that reduces the significant 4K video crop factor found on the Canon EOS R full-frame camera systems. With this adapter, photographers can use Canon EF full-frame lenses with the Canon RF mount, significantly reducing the 4K crop on the EOS R from 1.75x to 1.24x and the crop on the EOS RP from 1.63x to 1.15x.

As with the company's existing Speed Boosters, it works by condensing the main lens's field of view down into a smaller region: reducing the net focal length by 1.4x and hence lowering the F-number by one stop, compared with the adapted lens's setting. A 50mm F2.0 combined with the adapter would become a 35mm F1.4.

The Metabones EF-RF Speed Booster ULTRA 0.71x is constructed of 5 elements in 4 groups and features an ultra-high index tantalum-based optics, magnification of 0.71x and a max output aperture of F0.9. The Speed Booster supports dual-pixel autofocus, video AF, plus it has IS lens support, a built-in Control Wheel for accessing various functions like shutter speed and ISO, an LED indicator and automatic adjustment of the autofocus speed.

As far as construction is concerned, Metabones used a rubber gasket to help protect against moisture and dust, as well as flocking to cut down on internal reflections. The Speed Booster is made from brass and aluminum alloy with chromium plating and a satin finish. The tripod head is detachable and can be used with popular ball heads from Photo Clam, Arca Swiss and Markins.

The new ULTRA model wasn't designed for still photography, Metabones explains, but it can be used as such if the camera is in APS-C mode. Lens compatibility is fairly extensive and includes:

  • Canon EF lenses
  • Canon EF extender
  • Carl Zeiss EF lenses
  • Sigma EF lenses
  • Tamron EF lenses
  • Tokina EF lenses
  • Contax N lenses modified to Canon EF by Conurus

The Speed Booster can also be used with the Contax 645 NAM-1 adapter that has been modified for Canon EF, but it can't be used with Canon EF-S lenses nor with APS-C lenses. Metabones stresses that those latter lenses 'DO NOT WORK AT ALL.'

The Metabones EF-RF Speed Booster ULTRA 0.71x is available now for $479.