Abstract: The combination in optical series of a microscope objective lens system with a first positive lens system, and a focusing module, all in combination with one another and with such other components as are required to provide a microscope image, allows the user of such a microscope, to continuously alter the active focal relationships of the microscope by continuously varying the afocal variator and the distance of the microscope objective lens system from the object which is undergoing examination, and all without the need to physically change the length dimension of the microscope system, and without the need to change the positions of any of the lenses outside of the afocal variator, and without the need to change the microscope objective lens. The focusing module includes, a front negative lens system, an afocal variator optical system, and a rear positive optical system. The afocal variator optical system includes in optical series a front positive lens, a negative lens, and a rear positive lens.