Using Autofocus

Calibration

For optimal performance, zoom the lens slowly across its entire zoom range, and then power off the camera. The camera will benefit from the lens metadata collected while you zoom the next time it is turned on, resulting in higher aufofocus performance. Refer to Lens Calibration for details.

Limitations

Autofocus is supported with the following known limitations

  1. The precision of the lens, both in terms of positioning and timing, plays a significant role in AF accuracy. Most lenses with ultrasonic or stepper motors and many other lenses perform satisfactorily in this regard.

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

  2. 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. 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.