Sony Alpha 7R II

Manual Focus Assist or MF Assist is a temporary zooming function that occurs automatically when the focus ring on the camera is turned during manual focusing. This briefly gives the user a much more detailed view of the centre of the scene being photographed so that more accurate manual focusing can be achieved before the picture is taken. This MF Assist is an optional feature that can be switched on or off from the settings menu, although it is so useful that most people using manual focus tend leave it on. In addition, the length of time for which the scene is temporarily zoomed is also controllable using the menu setting item just below the MF Assist, namely the Focus Magnification Time.