BTC EF to 4/3-mount w Booster

Features and Benefits

Electronic

Compatible with all MFT mount cameras, including G9II, GH7, GH6, GH5, OM-1, OM-D, Blackmagic Cinema Camera, Blackmagic Pocket Cinema Camera and JVC GY-LS300.
Autofocus
Phase-detection autofocus (PDAF) on supported camera bodies*
Iris/aperture controlled by the camera body
Smooth iris support with the latest Canon (2009+), Tamron (SP series 2013+) and Sigma (2016+) lenses
Image stabilization lens support (Canon IS, Sigma OS, Tamron VC)
Support for cameras with in-body image stabilization (IBIS)
Electronic manual focusing (e.g. EF 85/1.2L II, EF 50/1.8 STM and discontinued EF 50/1.0L)
EXIF (focal length, aperture, zoom range)
Distance and zoom display (requires lenses supporting distance information)
Cinema EOS lens support (CN-E 18-80mm T4.4 L, CN10x25 25-250mm T2.95, etc.), including AF, auto iris and servo zoom (may require external power)
LED indicator shows adapter status.

Mechanical

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 MFT mount connection from dust and moisture.

Limitations

AF may not work if the maximum aperture of the lens plus any EF Extender or other teleconverter attached is smaller than f/8.
Some older third-party lenses may have unsatisfactory AF accuracy.
No support for Focus Stacking and Focus Bracketing.
Most 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.
Use of Canon Cinema lenses such as CN-E 18-80mm T4.4 L IS KAS S and CN 10x25 25-250mm T2.95 for still photography is not supported. (Functional, but slower than lenses designed for still photography.)
Iris changes are 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. This limitation does not apply to Cinema EOS lenses which permit fine resolution iris control, such as CN-E 18-80mm T4.4 L IS KAS S and CN 10x25 25-250mm T2.95.
No support for in-camera correction such as peripheral shading, CA and distortion

*If C-AF and C-AF-TR become greyed out on OM System OM-1, try turning on the "Keystone Correction" option on the camera, and then turn it off.

GH7, XL or ULTRA?

In a nutshell, we recommend XL for full frame lenses and ULTRA for DX/APS-C lenses. For the long story, read the 'limitations' column.

Compatible with OM SYSTEM

Our EF-MFT line-up has been refreshed to "Mark II" by redesigning to clear the faux-pentaprism of OM SYSTEM OM-1. For details, as well as additional benefits of "Mark II", read press release.

Unsupported Lenses

Incompatible

Tamron 70-300mm F/4-5.6 VC USD A005

No AF Support

Tamron SP 17-50mm F/2.8VC B005

Tamron 28-300mm F/3.5-6.3 VC A20

Tokina Opera 50mm F/1.4

Sigma 18-125mm F/3.5-5.6DC OS HSM

AF may not be accurate, but may be usable on a camera with PDAF (GH7, OM-1. etc.)

Canon EF 50mm f/1.8 II

Canon EF 28-70mm f/3.5-4.5 II

Sigma 50mm f/1.4 EX HSM

Sigma 90mm F/2.8 macro (1988)

Tamron 18-250mm f/3.5-6.3 Di II Macro A18

Tamron 18-270mm F/3.5-6.3 VC PZD B008

Tamron 24-70mm f/2.8 VC USD A007

Tamron 28-300mm f/3.5-6.3 XR Di Macro A06

Tokina AT-X PRO 11-16mm f/2.8 DX (I)

Incompatible EF-S lens (insufficient clearance, even if modified)

Canon EF-S 10-18mm f4.5-5.6 IS STM

Canon EF-S 17-55mm f/2.8 IS USM

Canon EF-S 18-55mm f/3.5-5.6 IS II

Canon EF-S 18-135mm f/3.5-5.6 IS USM "Nano"

Unsupported List

Canon EF-S Lens (but third-party APS-C lenses are supported)

Panasonic and Olympus/OM Tele-converter

Lens correction such as peripheral shading, CA and distortion

Focus confirmation "chip" (e.g. Dandelion)

M42 screw mount adapters (see "Manual Focus Lens Compatibility" below)

Stacking non-Metabones/non-Conurus mount adapters on top (see "Manual Focus Lens Compatibility" and list of lenses which require modification below.)

Manual Focus Lens Compatibility

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.

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. Scratches and damages caused by rear protrusions on Speed Booster are not covered by warranty.

List of manual focus lenses which REQUIRE MODIFICATION to be used on Speed Booster