What’s Different. What sets the Speed Booster T Ultra apart from the XL is its 0.71x focal-length increase, its 1-stop maximum-aperture increase, and its autofocus support on select lenses.

Lens Compatibility. The adapter allows full-frame Canon EF and third-party EF-mount lenses to be used on compatible Micro 4/3 cameras.

Camera Compatibility This adapter offers limited autofocus, image stabilization, and aperture control with select Micro 4/3 cameras and Canon EF mount lenses. For more information, you can check the manufacturer’s list here.

Wider Focal Length and Increased Aperture. This version of the Speed Booster widens the mounted lens’s focal length by 0.71x, reducing the overall sensor-crop factor 2x to 1.42×. It also increases the mounted lens’s maximum aperture by 1 stop.

Electronic Communication. The adapter’s mount has electric contacts that allow you to use compatible lenses’ autofocus, aperture-control, and image-stabilization functions. For use with most lenses, the adapter doesn’t require a separate power source, and EXIF data is transferred and embedded into your footage.

Sturdy Design with Built-In Tripod Foot. The aluminum-alloy barrel and brass mounts give it a solid feel, with an Arca-Swiss compatible tripod foot that lets you mount the adapter itself directly to a tripod. This ensures the lens’s weight doesn’t put additional stress on the camera’s mount.