News |Metabones launches EF-RF Speed Booster to reduce EOS R 4K crop factor

Metabones launches EF-RF Speed Booster to reduce EOS R 4K crop factor

The new Metabones Speed Booster for Canon EF to RF mounts makes the EF lens 0.71x wider

makes the lens 0.71x wider.

Metabones has announced the Canon EF-RF mount T Speed Booster ULTRA 0.71x, price tag $479, which is designed to reduced the 4K crop factor from Canon EOS R cameras.

Metabones says the Canon EF-RF mount T Speed Booster ULTRA 0.71x will mitigate most of the 4K video crop factor from the EOS R (1.75x) and EOS RP (1.63x), reducing it to 1.24x and 1.15x respectively.

The Canon EF-RF mount T Speed Booster ULTRA 0.71x will adapt a Canon EF lens to the EOS R series RF mount and effectively makes the lens 0.71x wider.

The Canon EOS R Speed Booster increases maximum aperture by a stop, and it supports Dual Pixel AF and video AF. Other features include:


  • Increase maximum aperture by 1 stop. (with a maximum output aperture of f/0.9).
  • Increase MTF (details).
  • Makes lens 0.71x wider.
  • Advanced 5-element/4-group optical design incorporating ultra-high index tantalum-based optical glass by Caldwell Photographic in the USA (patent granted).


  • Autofocus. AF speed is properly adjusted to account for and leverage the shorter focal length and the brighter maximum aperture.
  • Dual-pixel autofocus (DPAF) and video AF support.
  • Focal length and aperture are adjusted in EXIF (see note 3).
  • Image stabilization (IS) lens support.
  • Store EXIF data (lens name, focal length and maximum/minimum aperture) for one manual lens in the adapter.
  • Build-in multi-function Control Wheel (turn/ push-in) for assignable functions(eg. ISO, shutter speed or aperture control, depth-of-field preview).
  • LED indicator shows communication status.
  • Powered by camera body. With most lenses, no external power source required.


  • The tripod foot is detachable and compatible with Arca Swiss, Markins and Photo Clam ball heads.
  • Flocking to reduce internal reflection.
  • Rubber gasket protects the RF mount connection from dust and moisture.
  • Aluminum alloy and brass construction with chromium plating.
  • Satin surface finish.

Via Canon Watch


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