Metabones MB_SPEF-M43-BT3 (MBSPEFM43BT3, MB SPEF M43 BT3, MB/SPEF/M43/BT3, mb_spef-m43-bt3) Canon EF Lens to Micro Four Thirds T Speed Booster XL 0.64x
Features and Benefits
Increase maximum aperture by 11/3 stop
Makes lens 0.64x wider
Patented 6-element/4-group optical design by Caldwell Photographic in the USA
Supports 4k video mode with DX lenses.
Auto focus on Panasonic Micro Four Thirds cameras
Can be powered either by camera body or by third-party external 5V power source (not included)
Iris/aperture controlled by the camera body.
Image stabilization (IS) lens support
Electronic manual focusing (e.g. EF 85/1.2L II and discontinued EF 50/1.0L)
EXIF (focal length, aperture, zoom range)
Distance and zoom display on camcorders (requires lenses supporting distance information)
Detachable tripod foot compatible with Arca Swiss, Markins and Photo Clam ball heads.
The interior is painted with flocking coating to further reduce the internal reflection.
Supports only Panasonic GH4, GH3, G3, G5, G6, G7, G10, GF3, GF5, GF6, GX1, GX8, Olympus E-PL7, Blackmagic Cinema Camera with Micro Four Thirds mount**, Blackmagic Pocket Cinema Camera***
EF-S lenses require modification to fit (but third party DX lenses can be used without modification)
EF-S and third party DX lenses may not cover the full Micro Four Thirds sensor in still photo and FHD video modes (but will cover 4k video mode)
No video AF for Olympus
AFC (continuous AF) and AFF (flexible AF) modes are not supported
Panasonic video AF may hunt more than a native lens
EF-mount lenses are not silent but may make audible click noises during autofocus operation and iris changes which may be picked up by the built-in microphone of the camera. An external microphone is recommended for video.
Iris changes are unsmooth but in 1/8 stop steps which may be noticeable in video recordings. Programmed exposure mode and shutter priority exposure mode should not be used for video.
No support for in-camera correction such as peripheral shading, CA and distortion
A new Micro-4/3 mount Speed Booster® adapter designed exclusively for the Panasonic GH4 and other selected Micro Four Thirds cameras (refer to the below camera compatbility table), with a magnification of 0.64x. The Speed Booster XL 0.64x uses an advanced 6-element optical design to achieve extraordinary optical performance at apertures up to an incredible f/0.80, a new record for Micro Four Thirds format.
The new Speed Booster XL 0.64x reduces the full-frame crop factor of the Panasonic GH4 from 2.0x to 1.28x, thus effectively transforming these cameras into APS-H format. When the GH4 is used in Cinema 4k video mode the horizontal full frame crop factor is reduced from 2.34x to 1.50x, thus effectively transforming the GH4 into a super-35 format 4k cine camera. In addition, the speed of any attached lens is increased by 11/3 stops, with a maximum output aperture of f/0.80 when an f/1.2 lens is used. For example, a 50mm f/1.2 becomes a 32mm f/0.80, which is the fastest aperture available for full size Micro Four Thirds format.
The Speed Booster XL 0.64x is similar to the Blackmagic-specific 0.64x BMCC Speed Booster (MB_SPEF-BMCC-BM1), but has been completely re-designed to meet the following requirements:
The working distance has increased by 1mm to permit use on the Panasonic GH4 and a number of other Micro Four Thirds cameras without touching the flexible outer cover of the camera’s shutter mechanism.
The optics are optimized for a standard Micro Four Thirds filter stack thickness of 4mm rather than the 2.4mm found in Blackmagic cameras.
The image circle diameter has been increased to 21.63mm so that the full 17.3mm x 13mm Four Thirds format is covered. This has been achieved while maintaining unusually high image quality over the 17.4mm image circle used by the Panasonic GH4 in its Cinema 4k video mode.
Although the Speed Booster XL 0.64x has extra clearance compared to the 0.64x BMCC Speed Booster, there are still a number of Micro Four Thirds cameras that are not supported due to mechanical clearance issues. This is summarized in the table below, which is color-coded so that Green means the camera is supported and Red means the camera is not supported.
Note that many of the Red-coded cameras actually do function, but there is a minor interference with the protective shutter cover. Although slight contact with the shutter cover appears to have no effect on the functioning or cosmetics of either the camera or the Speed Booster we cannot support these combinations due to possible risk of damage.
Autofocus with an Optimum Balance of Accuracy, Speed, Consistency and Reliability
New in Speed Booster XL for Canon EF Mount to Micro Four Thirds is autofocus support, subject to certain limitations (see table below for details). We are pleased to report that Panasonic Micro Four Thirds camera bodies are capable of autofocusing accurately even if the maximum aperture of the Speed Booster and the lens combined is in the sub-f/1.0 range. Although our first and foremost priority is accuracy, we are able to make great strides in autofocus speed as well.
Autofocus Lens Compatibility List
Tested by the community, thanks!
Accurate only on newer cameras such as Panasonic G7 and GX8
Canon EF 8-15mm f/4L USM Fisheye
Canon EF 20-35mm f/3.5-4.5 USM
Canon EF 24-105mm f/4L IS USM
Canon EF 28-80mm f/3.5-5.6 II
Canon EF 35-80mm f/4-5.6
Canon EF 40mm f/2.8 STM
Canon EF 50mm f/1.2L USM
Canon EF 50mm f/1.4 USM
Canon EF 70-200mm f/2.8L IS II USM
Canon EF 70-300mm f/4-5.6L IS USM
Canon EF 85mm f/1.2L II USM
Canon EF 100mm f/2.8L IS Macro USM
Canon EF 100mm f/2.8 Macro USM
Canon EF 100-400mm f/4.5-5.6L IS USM
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 EF 70-200mm f/2.8L IS USM (Mark I)
Canon EF 85mm f/1.2L USM (Mark I)
Canon EF 200mm f/2.0L IS USM
Canon EF 300mm f/2.8L IS USM (Mark I)
Canon EF 400/2.8L IS USM (Mark I)
Canon EF 70-200mm f/4L USM
Canon EF 135mm f/2L USM
Canon EF 200mm f/2.8L II USM
Canon EF 300mm f/4L IS USM
Canon EF 50mm f/1.8 II
Sigma 50mm f/1.4 EX HSM
Tamron 28-300mm f/3.5-6.3 XR Di VC A20
Manual focus only
Contax N lenses modified by Conurus
Zeiss ZE lenses
Tamron SP 17-50mm f/2.8 VC B005
Some improperly-made M42 screw mount adapters may short the electronic contacts of the Speed Booster and cause damage to the Speed Booster and/or camera body.Manual Focus Lens Compatibility
Focus confirmation "chips" such as Dandelion are incompatible.
Many manual focus lenses (e.g. OM 28/2.8, OM 50/1.8, Leica R 15/3.5) have rear protrusions (spikes, levers, other appendages) which would damage the optics and/or housing of Speed Booster. They need to be modified before they can be safely used on Speed Booster. Check and make sure there are no rear protrusions from the adapter/lens combination before using on Speed Booster.
Metabones Speed Booster XL 0.64x Specifications:
Crop Factor for Full Micro Four Thirds format: 1.28x
Crop Factor with GH4 in Cinema 4k (4096 x 2160) Video Mode: 1.5x
Maximum Output Aperture: f/0.80 (with f/1.2 lens attached)
Rectilinear Distortion: < 0.8%
Lens Elements/Groups: 6/4
Length Reduction: 6.2 mm
Camera Mount: Micro Four Thirds
Image Format: 17.3 mm x 13.0 mm (full Micro Four Thirds format)