In accordance with one embodiment of the present invention, a microscope is provided comprising a microscope assembly and a lens positioner. The lens positioner comprises a tension control assembly, an adjustable lens extension assembly, and a tensile cord coupling the tension control assembly to the adjustable lens extension assembly. The tension control assembly is configured to control the degree of tension in the tensile cord. The adjustable lens extension assembly comprises a flexible linkage subassembly and a lens support subassembly. The flexible linkage subassembly comprises a proximal end and a distal end and is configured such that the distal end is movable relative to the proximal end through a plurality of degrees of freedom of movement. The lens support subassembly is secured to the distal end of the flexible linkage subassembly. The flexible linkage subassembly is further configured such that the ease at which its distal end moves relative to its proximal end is a function of the degree of tension in the tensile cord, as controlled by the tension control assembly.