Abstract: There is disclosed an end effector for a robotic positioner. The end effector has a frame adapted to connect to the robotic positioner, the frame defining a guide. A first gripper member is connected the frame and a second gripper member defines a follower operatively engaged to the guide, an engagement between the follower and the guide constraining the second gripper member to movement in at least one rotational movement about a virtual pivot spaced away from the first gripper member, the second gripper member, the follower and the guide. At least one actuator is connected to the second gripper member for moving the second gripper member toward and away from the first gripper member in the rotational movement.