Using Autofocus


Autofocus is supported with the following known limitations

  1. AFC (continuous AF) and AFF (flexible AF) modes are not supported.

  2. Video AF is not supported for Olympus.

  3. Video AF may suffer from more hunting than a native lens. Video AF effectiveness is dependent upon the lens' ability to make small, rapid changes with minimal latency.
  4. Unsupported lenses: previous generation Tamron VC lenses and Contax N lenses modified to EF mount by Conurus Canada.

  5. The precision of the lens, both in terms of positioning and timing, plays a significant role in AF accuracy. Most PDAF lenses with ultrasonic or stepper motors and many other lenses perform satisfactorily in this regard. Refer to the product page on Metabones' web site for the most up-to-date list of lenses tested to autofocus accurately.

  6. When an EF Extender is used with a Canon telephoto lens, autofocus is disabled if the combined maximum aperture of the lens and the EF Extender is slower than (numerically exceeds) f/5.6. This is a limitation imposed by the Canon lens itself and is not caused by the Speed Booster/Smart Adapter.

Recommended Settings and Precautions

  1. Set AF mode to AFS (single). AFC (continuous) and AFF (flexible) modes suffer from excessive hunting.

  2. Hand-shake, rapid subject movement, insufficient contrast, bright point light sources in the AF area, high ISO noise, multiple subjects of varying distance in the AF area or moiré may cause the camera to collect outdated or conflicting contrast detection data resulting in a negative impact on autofocus accuracy.

  3. We recommend turning the “Eye Start AF” (for camera models equipped with EVF) and “Quick AF” options off to conserve battery power.

  4. With a STM lens or a lens using electronic manual focusing (EMF) such as EF85/1.2L (both versions), manual focus needs to be explicitly enabled on the camera body. Set the AF mode of an Olympus camera under the 'A' menu to S-AF+MF (there are separate settings for stills and video), or enable the AF+MF option on Panasonic. Consult your camera's documentation on where to locate the setting.

Using video autofocus

  1. When the top dial is set to movie mode (if the camera is so-equipped), and a small aperture is chosen, the lens' aperture may momentarily open while AF takes place, and stops down again when AF locks. This is normal behaviour necessary for the AF system to work properly, and is exhibited by native Micro Four Thirds lenses as well. This will not happen during capture.
  2. For certain lenses, it may be better to turn the video continuous AF off in order to avoid unexpected hunting. Conduct testing to find the setting which best suits your shooting style and your lenses. You may also hold down the shutter release button halfway to temporarily stop the camera from adjusting focus.

  3. During continuous video autofocus, the lens' motor makes audible noises which are picked up by the camera's internal microphone. Use of an external microphone is recommended. For cameras without any microphone input, hold down the shutter release button halfway to stop the autofocus motor from moving, and only release it when subject moves out of focus. Another workaround is to turn “continuous AF” off under the video menu, and always manually half-press the shutter release button when subject distance changes.

  4. Single video AF is always available when you half-press the shutter release button, even if the camera is set to AF-S and "Continuous AF" is set to OFF. If it still doesn't work, check the "Shutter AF" option under the Custom menu ("gear" icon with letter "C") and make sure that is set to ON.