Metabones Announces New Speed Booster ULTRA 0.71x For Canon EF to Micro Four Thirds

Metabones makes some truly revolutionary accessories for modern cameras, enabling users to adapt almost any glass out there to their camera bodies. The American company just announced a brand new addition to their Speed Booster line of focal reducers - the Speed Booster ULTRA 0.71x designed for Micro Four Thirds mirrorless cameras.

Like the ULTRA series for Sony E-mount, the new Speed Booster ULTRA for Micro Four Thirds mount cameras uses an advanced 5-element 4-group optical design incorporating ultra-high index tantalum-based optical glass.  However, the new design is specifically optimized for the Micro Four Thirds sensor and filter stack, and as a result achieves an astonishing level of performance that sets a new standard for focal reducers.


The Speed Booster ULTRA 0.71x adapts Canon EF lenses to Micro 4/3 mount cameras like the Panasonic GH4 and reduces the crop factor in 4K (4096 x 2160) Cinema mode to 1.66x from the normal 2.3x. The new Speed Booster ULTRA for Micro Four Thirds also supports Contrast-Detect auto-focus on Panasonic MFT cameras. (For a list of supported lenses scroll to the bottom of this post).

Like the revolutionary original Metabones Speed Booster® announced in January 2013, the Speed Booster ULTRA m43 has a magnification of 0.71x, and so it effectively reduces the crop factor of mirrorless Micro Four Thirds mount cameras from 2.0x to 1.4x in Full HD.

However, the new ULTRA design makes very effective use of exotic materials at the furthest limit of glassmaking technology, and as a result is almost perfectly corrected for use with all fullframe SLR lenses regardless of aperture.  The Speed Booster ULTRA m43 will also work extremely well with many DX and APS-C format lenses provided the image circle of the lens is large enough.

Optical performance of the new Speed Boosters is so good that the MTF of any lens attached to it will be improved.  Even the latest generation of ultra-high performance SLR lenses such as the Zeiss Otus series can be improved by adding a Speed Booster ULTRA m43.


Like all Metabones Speed Boosters, the Speed Booster ULTRA m43 is optimized to correctly account for the camera’s filter stack located near the sensor surface3.  This is especially critical at the extremely large apertures made possible by Speed Booster technology.  As a result of this careful optimization, an enormous range of full-frame optics, ranging from vintage film lenses to the latest digital designs, will function flawlessly when adapted to Micro Four Thirds camera bodies.


Model Code:  MB_SPEF-m43-BT4 (Canon EF mount), MB_SPNFG-m43-BM3 (Nikon F/G mount)

Color: Black Satin exterior; Black Matte interior

Magnification:  0.71x

Crop Factor for Full Micro Four Thirds format:  1.42x

Crop Factor with GH4 in Cinema 4k (4096 x 2160) Video Mode:  1.66x

Maximum Output Aperture:  f/0.90 (with f/1.2 lens attached)

Rectilinear Distortion:  < 0.7%

Lens Elements/Groups:  5/4

Length Reduction:  5.5 mm

Camera Mount:  Micro Four Thirds

Compatibility:  All Micro Four Thirds cameras are supported

Image Format:  17.3 mm x 13.0 mm (full Micro Four Thirds format)

Lens Mounts:  Canon EF and Nikon F/G at release; other mounts to follow in the near future

Lens Compatibility:  Any full-frame (36 mm x 24 mm format) SLR lens with the appropriate mount can be used.  DX format lenses can be mounted but may result in vignetting when the full Micro Four Thirds format is used, depending on the lens.  DX lenses are fully supported when used on the Panasonic GH4 in Cinema 4k mode, and will function without abnormal vignetting.  Canon EF-S lenses are not supported, but third-party EF-mount APS-C lenses can be mounted and will have full electronic functionality.

Autofocus supported for Canon EF version subject to the following known limitations:

  1. Contrast-detect autofocus support on Panasonic cameras only.
  2. AFC (continuous AF) and AFF (flexible AF) modes are not supported.
  3. Video AF may hunt more than a native lens.
  4. Autofocus is not supported with previous generation Tamron VC lenses and Contax N lenses modified to EF mount by Conurus Canada. (Newer Tamron lenses such as the 24-70/2.8 VC A007 and 70-200/2.8 VC A009 work fine.)
  5. Switching from manual focus or full-time manual focus (FTM) to autofocus may occasionally result in focus failing to lock or inaccurate focus. Activating autofocus for a second time will resolve this issue.
  6. AF accuracy is lens-dependent.
Canon EF20-35mm f/3.5-4.5 USMCanon EF24-105mm f/4L IS USMCanon EF35-80mm f/4-5.6Canon EF40mm f/2.8 STM

Canon EF50mm f/1.2L USM

Canon EF50mm f/1.4 USM

Canon EF70-200mm f/2.8L IS II USM

Canon EF70-300mm f/4-5.6L IS USM

Canon EF85mm f/1.2L II USM

Canon EF100mm f/2.8 USM macro

Sigma 18-35mm f/1.8 DC Art

Sigma 18-125mm f/3.8-5.6 DC HSM

Tamron SP 24-70mm f/2.8 Di VC USD A007

Tamron SP 70-200mm f/2.8 Di VC USD A009

Tokina AT-X PRO 11-16mm f/2.8 DXII

Canon EF50mm f/1.8 IICanon EF200mm f/2.8L II USMSigma 50mm f/1.4 EX HS 

Special Features:  Long-throw clickless aperture ring on Nikon F/G version; IS lens support, IBIS camera support, auto-exposure and in-camera aperture selection with Canon EF version.

Dimensions: 25 x 76 x 72mm for Canon EF version

Weight: 161 grams for Canon EF version

Tripod Mount:  Robust removable type with Arca Swiss compatibility

The Speed Booster ULTRA for Micro Four Thirds will be available starting in July 2015 from the Metabones website and its worldwide dealer network for US $649 (Canon EF mount) and US $479  (Nikon F/G mount), plus shipping and applicable taxes and duties.  Additional lens mounts are being developed and will be released in the near future.

UK pricing has not been finalised yet, but keep cheeking on where we'll update the pricing once it becomes available for the UK.

For a list of Metabones adapters we offer head over here.