I decided to mess with the Tank version of game and was experimenting with controls. I use TrackIR.
When I go to binoculars I can control the direction of where I am looking by the mouse or by the controls I have set up for moving the turret and gun. But I can't do so with TrackIR. To use that I have to be in an external view. Plus I can't fire the gun in binocular view.

Mouse takes over from TIR and turret rotation when the binocular is selected in my set up. Can't fire gun in bins mode; align gunsight to spotted target with binocular view by pressing primary weapon trigger and you will be in zoom mode if previously selected afore bino use.