Metabones Speed Booster Ultra 0.71x Adapter
The Metabones MB_SPEF-E-BT4 is a lens accessory from Metabones — known for its 0.71x Focal Reducer and One-Stop Light Gain. Used copies start from $225 on GearFocus, with buyer protection on every purchase.
Metabones Speed Booster Ultra 0.71x Adapter
Used Metabones MB_SPEF-E-BT4 Listings on GearFocus
Good
$225.00
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Overview — Metabones MB_SPEF-E-BT4
Key Features — Metabones MB_SPEF-E-BT4
0.71x Focal Reducer: Compresses the image circle of Canon EF lenses onto the smaller Sony E-mount sensor, effectively widening the field of view by 0.71x.
One-Stop Light Gain: The optical reduction increases maximum aperture by approximately one full stop, so an f/2.8 lens effectively becomes f/2, improving low-light performance.
Canon EF to Sony E-Mount: Allows full-frame Canon EF lenses to mount directly onto Sony E-mount mirrorless cameras, giving EF glass users a path into the Sony ecosystem.
Autofocus Support: Maintains electronic communication between compatible Canon EF lenses and Sony E-mount bodies, preserving autofocus functionality rather than limiting users to manual focus only.
Multi-Element Optical Design: The Ultra version uses an upgraded optical formula with premium glass elements to minimize aberrations and maintain sharpness across the frame.
EXIF Data Retention: Electronic contacts pass lens metadata including focal length and aperture information through to the camera body for accurate EXIF recording.
Specifications — Metabones MB_SPEF-E-BT4
| Spec | Detail |
|---|---|
| Camera System | Mirrorless |
| Zoom Prime | Other |
| Auto Focus | Yes |
| Focus Type | Auto, Manual |
| Image Stabilization | None |
| Mount lens | Canon EF, Sony E |
| Compatible Mount | Canon EF, Sony E |
Description — Metabones MB_SPEF-E-BT4
The Metabones Speed Booster Ultra 0.71x Adapter bridges the gap between Canon EF mount lenses and Sony E-mount mirrorless camera systems. Built specifically for mirrorless use, this adapter maintains electronic communication between lens and body, enabling both autofocus and manual focus operation as confirmed in the specifications. The autofocus support means shooters are not forced into a manual-only workflow when adapting their Canon EF glass to a Sony E-mount body.
It's worth noting that the adapter does not incorporate any image stabilization of its own, so users relying on optical stabilization will need to source that from their lens or camera body. For content creators and photographers with existing Canon EF lens investments who have moved to Sony E-mount mirrorless, this adapter provides a electronically connected, AF-capable solution to continue using that glass on their current system.
Pros — Metabones MB_SPEF-E-BT4
- ✓Supports both autofocus and manual focus (focusType: Auto, Manual)
- ✓Compatible with Canon EF lenses on Sony E-mount mirrorless cameras (mount.lens: Canon EF, Sony E)
- ✓Designed specifically for mirrorless camera systems (cameraSystem: Mirrorless)
Cons — Metabones MB_SPEF-E-BT4
- ✗No image stabilization built into the adapter (imageStabilization: None)
- ✗Limited to Canon EF lenses only on the lens side — other EF variants not listed in specs
- ✗No hotshoe pass-through available (mount.hotshoe: null)
Videos — Metabones MB_SPEF-E-BT4
Don't Buy This Adapter - It Will Break Your Camera! — Mark Wiemels
Frequently Asked Questions — Metabones MB_SPEF-E-BT4
Which lenses and cameras is this adapter compatible with?+
According to the specifications, this adapter is compatible with Canon EF mount lenses and Sony E-mount mirrorless cameras. Those are the only two mount systems listed in the specifications data.
Does this adapter support autofocus?+
Yes. The specifications confirm that autofocus is supported (autoFocus: true), and the focusType field lists both Auto and Manual as available focus modes.
Does the adapter include image stabilization?+
No. The specifications explicitly state that image stabilization is set to None, meaning the adapter itself does not provide any stabilization. Any stabilization would need to come from the attached lens or the camera body.
Does this adapter work with DSLR cameras?+
The specifications indicate this adapter is designed for mirrorless camera systems (cameraSystem: Mirrorless), specifically for Sony E-mount bodies. It is not listed as compatible with DSLR camera mounts.
Is there a hotshoe connection on this adapter?+
No. The specifications show the hotshoe field as null, meaning there is no hotshoe pass-through on this adapter.