Metabones SPEF-M43-BT3 Canon EF to MFT lens mount adaptor

Canon EF lens adapter to camera bodies with MFT mount. It has a magnification of 0.64x, which effectively reduces the crop factor of micro four-thirds mirrorless mounting cameras from 2.0x to 1.28x. 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. Similar to the BMCC 0.64x Speed Booster specific to Blackmagic, but has been completely redesigned to meet the following requirements:

The working distance has been increased by 1mm to allow use in Panasonic's GH4 and other four-thirds micro cameras without touching the flexible outer cover of the camera's shutter mechanism. The optics are optimised for a standard filter stack thickness of 4mm instead of the 2.4mm found in Blackmagic cameras. The diameter of the image circle has been increased to 21.63mm to cover the full four-thirds format of 17.3x13mm. This has been achieved by maintaining an unusually high image quality in the 17.4mm image circle used by Panasonic GH4 in its Cinema 4k video mode.

Although it has additional free space compared to the BMCC 0.64x, there are still a number of four-thirds micro cameras that are not compatible due to mechanical free space problems. Note that many of the incompatible cameras actually work, but there is less interference with the protective cover of the shutter. Although a slight contact with the shutter cover does not appear to have any effect on the performance or aesthetics of the camera or Speed Booster, these combinations cannot be supported due to the possible risk of damage.

What is new in Speed Booster XL for Canon EF at micro four thirds is the autofocus support (subject to certain limitations). The bodies of the Panasonic four-thirds micro cameras are able to precisely autofocus even if the maximum aperture of the Speed Booster and the combined lens is in the sub-f/1.0 range. 

Some improperly made M42 screw mounting adapters can shorten the electronic contacts of the speed booster and cause damage to the speed booster and/or camera body.

Many manual focus lenses have rear protrusions (tips, levers, other appendages) that could damage the Speed Booster's optics and/or housing. They must be modified before they can be used safely in the Speed Booster. Check and make sure that there are no back bumps in the adapter/lens combination before using the Speed Booster. Scratches and damage caused by the rear bumps of the Speed Booster are not covered by the warranty.

  
Metabones SPEF-M43-BT3 adapter features

• Magnification - 0.64x
• Trim factor for the entire Micro Four Thirds format - 1.28x
• Culture factor with GH4 in Cinema 4k (4096 x 2160) Video mode - 1.5x
• Maximum output aperture - f/0.80 (with built-in f/1.2 lens)
• Rectilinear Distortion - < 0.8%.
• Lens Elements/Groups - 6/4
• Reduction in length - 6.2mm
• Mounting the camera - Micro four thirds
• Image format - 17.3mm x 13.0mm (full micro four-thirds format)
    
• Optics
  • Increase maximum opening by 11/3 of the stop
  • Increase MTF
  • Makes the lens 0.64 times wider
  • Patented 6-element/4-group optical design by Caldwell Photographic in the U.S
  • Supports 4k video mode with DX lenses (except GH5)
       
• Electronic
  • Autofocus
  • It can be powered by the camera body or by an external 5V power supply (not included)
  • Iris/opening controlled by camera body
  • Soft iris compatibility with the latest Canon (2009+), Tamron (SP 2013+ series) and Sigma (2016+) lenses
  • Image stabilization (IS) lens compatibility
  • Support for cameras with body image stabilization (IBIS), including Panasonic GX7, GX8, GX80/85 and Olympus cameras
  • Electronic manual focusing (e.g. EF 85/1.2L II and EF 50/1.0L discontinued)
  • EXIF (focal length, aperture, zoom range)
  • Distance and zoom visualization on camcorders (requires lenses that support distance information)
  • EOS Canon Cinema Lens (CN-E Compact-Servo) compatible, including AF (requires external 5V power via micro USB port), auto iris and servo zoom
      
• Other
  • Detachable tripod foot compatible with Ark Swiss, Markins and Photo Clam
  • The opening is flocked with felt material to reduce internal reflection