Using the LA-EA1 or LA-EA3: The focus mode can be switched only when using an SAM/SSM lens. You can switch between auto focus (AF) and manual focus (MF) by using the AF/MF switch on the lens.
Using the LA-EA2 or LA-EA4: If you are not using an SAM/SSM lens go into the Camera menu and select the AF/MF Select option. However, if you are using an SAM/SSM lens simply use the AF/MF switch on the lens.
IMPORTANT: When using the NEX-7 with an SSM lens set the AF/MF/AEL switch lever to the AF/MF position, then press the AF/MF button to switch between focus modes.
NOTE: The focus mode cannot be switched by going to the menu of the camera when using an SAM/SSM lens.