Abstract: An endoscope coupler apparatus and method includes a sealed chamber and a lens assembly movable within the chamber for optically adjusting an image to be received by a video camera. The optical adjustment may be, for example, a focus adjustment or a zoom or orientation adjustment, etc. In a preferred embodiment, spaced permanent drive magnets located in an outer rotatable frame situated outside of the chamber are magnetically coupled with respective permanent driven magnets secured to an inner rotatable frame within the sealed chamber. The outer frame is rotatable but not longitudinally movable about the chamber and rotates the drive magnets and, therefore, the driven magnets. The inner frame is secured to a rotatable cylindrical housing which engages a lens assembly. Rotation of the driven magnets and the cylindrical housing moves the lens assembly longitudinally in response to rotation of an adjustment ring attached to the outer frame.