A coupler for connecting an endoscope to a camera including a cylinder having a zoom lens and a focus lens therein. A zoom adjustment member engages the cylinder with a first coefficient of friction and is movable relative thereto to cause axial movement of the zoom lens. The zoom adjustment member is operatively connected to a focus adjustment member such that movement of the zoom adjustment member causes the focus adjustment member to move thereby moving both the zoom lens and the focus lens axially. The focus adjustment member engages the zoom adjustment member with a second coefficient of friction and is movable relative thereto to cause axial movement of the focus lens within the cylinder. The first coefficient of friction is greater than the second coefficient of friction such that movement of the focus adjustment member does not cause movement of the zoom adjustment member.
