Andy Westlake tests a mount adapter that promises to autofocus any lens on the Sony Alpha 7 II and Alpha 7R II full-frame mirrorless cameras
Techart PRO Leica M – Sony E autofocus adapter review: Bluetooth programmability
The least conventional aspect of this device is its Bluetooth programmability. The basic idea makes sense: because the adapter communicates electronically with the camera it can report lens information for inclusion in EXIF data, with the focal length also allowing the in-body image stabilisation work correctly. But rather than maintaining a connection to a smartphone and letting you specify the lens in use via an app, it works more obtusely.
To activate the Bluetooth, you first change the aperture setting to f/90, then press the shutter button and turn off the camera. You can then pair your phone using the free Techart app, and program in information for your lenses. Each gets associated with an aperture value that you’ll set on the camera; for example, at the adapter’s factory settings f/25 is used for a 50mm f/1.4. When you change lenses, selecting the corresponding aperture and pressing the shutter button updates the lens information passed to the camera.
This means you don’t need to carry a phone around to select a new lens each time you switch, but do have to remember which aperture setting corresponds to each lens. Another snag is that at the time of writing, the app is only available for Android and in Chinese, and I couldn’t persuade it to program in all the lenses I wanted to use. In the end I decided to set the Alpha 7 II’s IS system for manual focal-length configuration via the C3 button instead.