Wide range zoom system

摘要

A wide range zoom system, for microscopes. The zoom system includes five lens groups, of which, starting at the object side, the second and fourth lens group are displaceable in the axial direction relative to the first, third and fifth lens group. A stop of variable opening diameter that is stationary relative to the first, third and fifth lens group is provided between the second and fourth lens group, wherein the maximum opening diameter of said stop is in middle zoom magnifications. As magnification increases, the object-side aperture increases non-linearly in relation to the magnification, such that in regions of low magnifications the object-side aperture increases more sharply than in regions of higher magnifications.

主权项

1. A wide-range zoom system for use in microscopes, the system comprising:
five lens groups, of which, counting from an object side toward an image side, the second lens group and the fourth lens group are axially shiftable relative to the first lens group, the third lens group and the fifth lens group, and in which a diaphragm of variable aperture diameter is provided between the second and the fourth lens group in a stationary position relative to the first, third and fifth lens groups, the aperture diameter increases monotonically as the zoom magnification is increased from a smallest to a medium zoom magnification, the diaphragm has a maximum aperture diameter at the medium zoom magnification, and the aperture diameter is decreases monotonically as the zoom magnification is further increased, so that, as the magnification is increased, the object-side aperture increases nonlinearly relative to the magnification in such a way that in lower magnification ranges the object-side aperture increases at a higher rate than in higher magnification ranges, and wherein the system has an entrance pupil diameter greater than 35 mm at the final magnification.