A couple of years ago, Metabones released firmware updates for their EF-E Speed Boosters and EF-E Smart Adapters that introduced 10 frames per second max continuous autofocus to the Sony A9 mirrorless camera. Now, Metabones has released a new firmware update which adds that functionality for the Sony A7III, too.
The firmware update can be applied via USB to the EF-E Smart Adapter IV/V/Cine and EF-E Speed Booster ULTRA I/II adapters. Each of these products can have their firmware updated over USB. The company says that some older adapter models can be updated to the new firmware, too, however, as they do not possess a USB port, you’ll have to send them back to the factory to have the firmware update implemented.
10fps is a “theoretical maximum” and will depend on various factors, like the lens choice, camera settings, subject movement, etc. Metabones has some recommendations to help keep the speed as fast as possible…
To achieve the highest possible AF-C frame rate on A7 Mark III, the adapter is set to “Advanced Mode”. On the camera we recommend setting “Priority Set in AF-C” to “AF” for the best accuracy and the highest hit rate, even though that will decrease the frame rate. 10 fps is the theoretical maximum and just how close we get to that is highly dependent upon the AF speed of the lens used and the speed of subject movement.
The fastest frame rate is achieved when the subject is at or near the center where phase-detection autofocus (PDAF) is used. Unfortunately only the central PDAF points are effective, because using all of the PDAF points of the camera would have required metadata about the optical formula of the specific lens used, which we do not have. All the PDAF points can be used by setting the Speed Booster or Smart Adapter to “Green Mode”, although the periphery points will still not be as effective as the central ones.