This T Speed Booster Ultra 0.71x Adapter from Metabones allows a full-frame Canon EF-mount lens to be used on a Canon EF-M mount camera. The adapter's optics help to maximize the connected lens's apparent angle of view while providing a one-stop increase for the camera over the lens's aperture range.

A full-frame Canon EF-mount lens is designed to project an image that is larger than a Canon EF-M mount camera's APS-C sensor. Ordinarily, that sensor would only be able capture the center portion of the projected image, creating an in-camera "crop factor." Inside this adapter, five optical elements in four groups condenses the light from the full-frame lens and effectively reduces the crop factor. This also makes available to the sensor an additional one stop of light throughout the lens's aperture range.

This adapter is constructed from aluminum alloy for durability while minimizing weight and its mounting rings are made with brass to further prevent wear-and-tear. An internal, matte black coating prevents the appearance of reflections within the adapter barrel, and to help reduce stress on the camera mount when placed on a tripod, the adapter includes a detachable Arca-type compatible tripod foot with 1/4"-20 threads.

This T Speed Booster Ultra 0.71x Adapter supports electronic communication between an attached camera and lens. If the lens includes autofocus, image stabilization, as well as camera-controlled aperture functions, this adapter is intended to allow use of those features. Also, if an attached lens is capable of generating EXIF metadata when used with a directly compatible camera, this adapter is designed to transfer that information, so it can be saved along with image files generated the combined Canon EF-mount lens and Canon EF-M mount camera.

Canon EF Lens to Canon EF-M Body    Full-Frame Lens to EF-M Camera Body    0.71x APS-C Crop Factor Compensation    1-Stop Increase in Lens Apertures    Supports In-Camera Aperture Control    Transfers Lens EXIF Metadata to Camera    Anti-Reflective Matte Black Interior    Brass Mounting Rings    Removable, Arca-Type Tripod Foot    1/4"-20 Tripod Foot Accessory Threads

• Allows a full-frame Canon EF-mount lens to be used on a Canon EF-M mount camera
• Supports electronic communication between camera and lens to enable autofocus, image stabilization, on-camera aperture control, and EXIF metadata generation when possible
• 0.71x magnification maximizes angle of view of combined camera and lens
• Provides a 1-stop increase for the camera over the lens's aperture range
• Five lens elements in four groups for optical clarity as well as color fidelity
• Internal, black matte coating minimizes the appearance of reflections within the adapter barrel
• Aluminum alloy components for weight reduction
• Brass mounting rings prevent wear-and-tear
• Detachable Arca-type tripod foot with 1/4"-20 threads can be used to reduces stress on a connected camera's mount
• Locking mechanism for secure attachment of lens with push-button release

Related Questions and Answers

Q: 1. I noticed on 10 Sep. 2020 Sean had asked if FD lenses could work with this booster and received a negative answer. If an FD lens has a FD to RF mount adapter on the back of the FD lens would the optical path produce sharp images at infinity focus? Of course the legacy FD lens functions would be fully manual meaning no auto focus or auto aperture.

A: The FD to EF adapters have a 1.4x teleconverter which would almost negate the 0.71x factor of the booster. For example 50mm x 1.4 (with the FD to EF adapter) equals 70mm. The booster reduces is by 0.71x thus making it 49.7mm. Metabones makes this adapter for mounting FD lenses to the RF cameras (just an adapter, not a booster): https://bhpho.to/2XeOOHG.

Q: 2. Can anyone confirm if this adapter works with the Canon 85mm L 1.4 IS? I have the Viltrox Speedbooster and it’s not compatible and the IS and AF go crazy on that mount. I’m using an M6 MK II for reference.

A: Yes, it is compatible with the 85mm 1.4L.

Q: 3. Will this work with S35 v-Raptor?

A: On paper, it is possible to use the Metabones T Speed Booster Ultra 0.71x Adapter for Canon Full-Frame EF-Mount Lens to Canon RF-Mount Camera. You may run into issues that will not have RED support however.

Q: 4. So if I put this on the Sigma 24mm f1.4 Prime Lens, what would it make the aperture on it? Also does it work with that lens?

A: This is compatible with the Sigma 24mm f/1.4 DG HSM Art Lens for Canon, and it'll be roughly equivalent to a f/0.9.

Q: 5. If I put this on an EOS R with the EF 8-15mm fisheye lens, will it get rid of the top and bottom crop seen in all video modes at the 8mm full-circle fisheye view, also using current firmware on camera and speedbooster if it has it?

A: I just tested this for you. So with the original Canon adapter, because of the crop you don't get the full 8mm circle [ in 4K. 1080P you do get the full circle no crop ]. Now with this speed booster, even in 4K you get the full circle at 8mm. So you will get the black edges and the spherical look in the middle.

Q: 6. will the assignable wheel be recognized by komodo? Can you assign it to adjust iris?

A: According to the manufacturer, the RED Komodo camera (firmware V1.5.3) is not compatible with the Control Wheel function of the Metabones T Speed Booster Ultra 0.71x Adapter for Canon Full-Frame EF-Mount Lens to Canon RF-Mount Camera.

Q: 7. Dan, In your response to Muhammed you said "a 50mm f1.8 would look like a 57mm lens with an f1.4 aperture." You said it has a crop of 0.71 so don't you mean it would look like a "35mm" lens with an f1.4 aperture? Was "57mm" correct?

A: 57mm is correct.

Q: 8. If I have a f/1.4 lens, will it become an f/1.1 or f/1.0 lens with this adapter? Also, will this adapter allow for EF and Ef-S lenses to now be used, like the Canon EF 50mm f/1.8 STM Lens, and will no longer need a Canon EF-EOS M Adapter or Vello Canon EF-EOS M Adapter for the Canon M6 MKII? Moreover, is there a 0.64 equvelant of this speedbooster that is compatible with the Canon M6 MKII? Thanks!

A: The adapter only allows EF lenses, and there is no .64 adapter currently available. As far as your aperture question, aperture is also affected by crop factor thus a f/1.8 lens would be a f/2.28 equivalent on an APS-C, and if you use this adapter you'll reclaim that light that is no longer falling the sensor so, roughly it'll be a f/2.0 equivalent. Basically, (Aperture x 0.71) x Crop Factor.

Q: 9. If i have eva1 and I want to mount 16-35 2.8 canon ef on it, it will work and help reduce the focal ? now 16mm look like 24mm and I want it to be\look wider

A: This adapter is made for Canon EF Lenses to Canon EF-M mirrorless cameras.

Q: 10. In picture mode, my 24-105 F4 actually gets registered and the vignetting goes away, but not so with my 16-35 ii. 2.8. What other lenses have you used that the metabones registers and does not vignette with, like the 24-105 f4 I mentioned?

A: this adapter is to be used only in the video mode of the camera. When recording UHD 4K video, a Canon RF-mount camera is only able to capture the center portion of the image projected on its sensor, creating an in-camera "crop factor." A Canon EOS R Mirrorless Digital Camera Body and a Canon EOS RP Mirrorless Digital Camera Body feature a UHD 4K crop factor of 1.75x and 1.63x respectively. Inside this adapter, five optical elements in four groups condenses the light from the full-frame lens and effectively reduces the crop factor to 1.24x and 1.15x respectively. This also makes available to the sensor an additional one stop of light throughout the lens's aperture range.