Why can't I adjust the aperture in movie mode when using a mount adapter with an A-mount lens?

As part of normal operations, the aperture cannot be adjusted in movie mode when using the LA-EA2 or LA-EA4 mount adapter with an A-mount lens.

When an A-mount lens is attached and the camera is in Auto Focus (AF) mode, the aperture value is automatically set to F3.5. Therefore, the aperture value cannot be changed when recording in AF-mode.

NOTE: If the mounted lens has an aperture smaller than F3.5, then the maximum available aperture will be set during movie recording.

To select a different aperture value, the camera must be set to Manual Focus (MF).