The Sony LA-EA4 Mount Adapter allows the use of Sony A-mount DSLR lenses
to work with your full frame E-mount compact system camera, such as the
Sony a7 and a7R.
The LA-EA4 features a built-in 15 point TTL phase detection AF system
and three cross sensors, so you’ll always capture sharp, detailed movies
and stills. The built-in AF motor allows autofocus with you’re A-mount
lenses. The adapter’s aperture drive mechanism enables Auto Exposure
(AE) with compatible A-mount lenses (not teleconverters).