If you were disappointed by reports that the Sony a9 struggles with long adapted Canon lenses, you might be able to take some comfort from Metabones' latest firmware update. The update for EF-E Smart Adapter Mark IV/V and EF-E Speed Booster Ultra adds autofocus support for medium and high burst modes on the Sony a9. However, since adapted lens support maxes out at 10 fps with AF, high burst mode simply runs at medium speeds (10 fps electronic, 5 fps mechanical).

We've have had a chance to give this update a go with a number of Canon mount lenses (including Sigma lenses), and are impressed with the results: with wider lenses (85mm and wider), you get phase-detect AF over most of the frame at 10 fps in Wide and Flexible Spot modes. With longer lenses (70-200/2.8, 100-400/4.5-5.6), focus starts to falter outside of the central region - something that doesn't happen with native E-mount lenses. In L drive mode (3 fps), the camera opens up the aperture in between shots - both for adapted and E-mount lenses, allowing the camera to continue focusing beyond F11 (at frame rates higher than 3 fps, the camera reverts to manual focus at apertures smaller than F11 - with both adapted and native lenses).

In manual focus mode, you can shoot up to 20 fps with adapted lenses. This is quite an impressive update for the Metabones adapter, and we've confirmed it to function significantly better with the a9 than the Sigma adapter (which has yet to issue a firmware update for the a9).

The firmware is available for download now from Metabones.

Firmware upgrade for EF-E Smart AdapterTM MARK IV/V and EF-E Speed BoosterTM ULTRA


This information is for the following models:

  • EF-E Smart AdapterTM MARK IV/V (model number MB_EF-E-BM4 / MB_EF-E-BT4 / MB_EF-E-BT5)
  • EF-E Speed BoosterTM ULTRA (model number MB_SPEF-E-BM2 / MB_SPEF-E-BT2 / MB_SPEF-E-BT3)


  • Name: Firmware update V0.57 for EF-E Smart AdapterTM MARK IV/V and EF-E Speed BoosterTM ULTRA
  • Release date: 26 Jun 2017
  • Benefits and improvements:
    - Added autofocus support during high speed and medium speed continuous drive (up to 10fps) on Sony A9 ("Green" mode only). Experiment with the "Priority Set in AF-C" setting for the best compromise between hit rate and frame rate for your shooting style. Overall performance depends on lens used. The camera does not use hunting while tracking is in operation. If subject movement exceeds the measurement range of the OSPDAF sensor, autofocus pauses. This is by design. The measurement range of the OSPDAF sensor decreases as the focal length increases. Except for the original Mark I Smart Adapter this feature is available for all subsequent Speed Boosters and Smart Adapters.
    - Enlarged PDAF area on supported cameras when adapter is in Advanced mode, with the advisory that AF performance may be unsatisfactory outside of the central portion of the frame.
    - Enabled AF illuminator (Advanced mode only).
    - There is an AF accuracy issue when using AF-S or DMF on Sony A9 and telephoto lenses with Metabones in "Advanced" mode, which affects this and all previous firmware versions. Green mode, which is set by default on Sony A9, is not affected (except for the original Smart Adapter Mark I, which does not support "Green" mode). A9 users are advised to not use "Advanced" mode but stick with the default "Green" mode. In addition, some telephoto lenses rarely exhibit this issue, such as EF 200/2.8L II USM, EF 400/5.6L USM and Tamron 150-600/5-6.3 VC USD A011. Investigation of this issue is still in progress.
    - Fixed AF issue with EF-S 10-18mm f/4.5-5.6 IS STM and EF-S 18-135/3.5-5.6 IS Nano USM lenses.
    - Fixed smooth iris support for 40/2.8 STM, 50/1.8 STM and Sigma 50-100/1.8 DC HSM Art 016.
    - Fixed CN-E 18-80 T4.4 L IS KAS S servo zoom used by the camera's zoom rocker and the lens' rocker in alternation.
    - Fixed CN-E 18-80 T4.4 L IS KAS S auto iris when adapter is in Green mode, where extremely bright conditions no longer causes the iris to close completely.
    - Fixed aperture display with Canon EF 300mm f/4L IS USM lens and Kenko Pro 300 teleconvertter.
    - Corrected W-T zoom scale display in "Advanced" mode for Speed Booster and Kenko Pro 300 teleconverter (except Mark I/II/III and original Speed Booster).
    - Faster aperture diaphragm for still photography in Advanced mode when Live Vide mode is set to Setting Effect OFF.
    - LED (if available) now shows solid magenta when adapter is connected to USB waiting for Metabones App to run.