having a front fixed lens or lens group and two movable lenses or lens groups in front of a fixed lens or lens group

Optical objectives with means for varying the magnification > by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective > with movable lens means specially adapted for focusing at close distances > having a front fixed lens or lens group and two movable lenses or lens groups in front of a fixed lens or lens group

Optical objectives with means for varying the magnification (anamorphotic objectives G02B13/08) > by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective > with movable lens means specially adapted for focusing at close distances > having a front fixed lens or lens group and two movable lenses or lens groups in front of a fixed lens or lens group