Call: +44(0) 208 397 1407
Rated 4.97 / 5
Sell Your Gear Find Out More ›
Free Delivery On Orders Over £300 incl VAT

Metabones MB_SPEF-EFR-BT1 Canon EF to Canon EFR Mount T Speed Booster ULTRA 0.71x - EOS R

  • £469.80
  • RRP: £427.68
Status   |   Usually dispatched within 24 hours


  • 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
  • Satin surface finish

Metabones MB_SPEF-EFR-BT1 (MB-SPEF-EFR-BT1, MB/SPEF-EFR-BT1, MB/SPEF/EFR/BT1, MBSPEFEFRBT1) Canon EF to Canon EFR Mount T Speed Booster ULTRA 0.71x - EOS R

Sharper corners, less distortion, reduced vignetting

Metabones EF-RF Speed Booster®  ULTRA 0.71x - to adapt Canon EF mount full-frame lenses to the new Canon RF mount. Filmmakers are now able to mitigate most of the 4k video crop factor of  EOS R (1.75x) and EOS RP (1.63x) and reduce it to 1.24x and 1.15x respectively and support the newly EOS C70(Super 35mm sensor). The field of view is now much closer to still photo mode. On the full-frame camera like EOS R, EOS RP, EOS R5, this Speed Booster is not intended for still photography but will work if the camera is configured to APS-C mode.

Speed Booster ULTRA uses an advanced 5-element/4-group optical design by Caldwell Photographic Inc., incorporating ultra-high index tantalum-based optical glass to achieve extraordinary optical performance with improved corner sharpness, distortion and reduced vignetting. Speed Booster ULTRA has a magnification of 0.71x,  effectively reducing the crop factor of 4k video on EOS R and EOS RP from 1.75x to 1.24x. The Speed Booster ULTRA design makes very effective use of exotic materials at the furthest limit of glassmaking technology, and as a result is well corrected for use with virtually all full-frame SLR lenses regardless of exit pupil distance. Thus, the Speed Booster ULTRA performs extremely well with professional-grade f/2.8 zoom lenses such as the 24-70mm f/2.8 and 70-200mm f/2.8 zooms by Canon to produce 17-50mm f/2.0 and 50-142mm f/2.0 high-speed zooms, respectively. Similarly, high-speed fixed focal length lenses such as a 50mm f/1.2 will be transformed into a 35.5mm f/0.9 lens with excellent contrast and resolution from the center all the way to the edges of the image.


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).


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.

  • Camera Mount: Canon RF
  • Lens Mount: Canon EF
  • Magnification: 0.71x
  • Optical Design: 5 Elements in 4 Groups
  • Tripod Mounting Thread: 1/4"-20 Female
  • Dimensions: ø: 2.8 x H: 0.8" / ø: 70.0 x H: 20.0 mm
  • Weight: 223 g

In The Box

  • Metabones Canon EF to Canon EFR Mount T Speed Booster ULTRA 0.71x
  • Tripod Foot
Be the first to review MB_SPEF-EFR-BT1 Canon EF to Canon EFR Mount T Speed Booster ULTRA 0.71x - EOS R. Write a review ›