Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
215 words
A zoom lens comprising, from front to rear, a first lens group of positive refractive power, a second lens group of negative refractive power movable along an optical axis for varying the image magnification, a third lens group of negative refractive power movable along the optical axis for compensating for the shift of an image plane resulting from the variation of the image magnification, a fourth lens group of positive refractive power, a stop, and a fifth lens group having an image forming function, said fourth lens group having a lens of which both lens surfaces are convex with the rear surface of strong curvature, and said fifth lens group having a front lens group and a rear lens group with a widest air separation intervening therebetween, said front lens group having a first lens of which both lens surfaces are convex, a negative second lens turning its concave surface toward the front, and a positive third lens of which the front surface is of strong curvature, said rear lens group having a negative fourth lens turning its concave surface toward the rear, a fifth lens of which both lens surfaces are convex, and a positive sixth lens of which the front surface is of strong curvature, and the following conditions being satisfied: 3.9<f4/fw<4.5 3.7<f5F/fw<5.2
Claim 2
Dependent Claim
215 words
A zoom lens comprising, from front to rear, a first lens group of positive refractive power, a second lens group of negative refractive power movable along an optical axis for varying the image magnification, a third lens group of negative refractive power movable along the optical axis for compensating for the shift of an image plane resulting from the variation of the image magnification, a fourth lens group of positive refractive power, a stop, and a fifth lens group having an image forming function, said fourth lens group having a lens of which both lens surfaces are convex with the rear surface of strong curvature, and said fifth lens group having a front lens group and a rear lens group with a widest air separation intervening therebetween, said front lens group having a first lens of which both lens surfaces are convex, a negative second lens turning its concave surface toward the front, and a positive third lens of which the front surface is of strong curvature, said rear lens group having a negative fourth lens turning its concave surface toward the rear, a fifth lens of which both lens surfaces are convex, and a positive sixth lens of which the front surface is of strong curvature, and the following conditions being satisfied: 3.9<f4/fw<4.5 3.7<f5F/fw<5.2
Claim 3
Dependent Claim
67 words
0<R5,2/R5,3<1.6 1.4<(D5F-D5R)/fw<1.75 where f4 and f5F are focal lengths of said fourth lens group and said front lens group respectively, (D5F-D5R) is an axial air separation between said front lens group and said rear lens group, R5,i is a radius of curvature of the i-th lens surface counting from front in said fifth lens group, and fw is the shortest focal length of the entire lens system.
Claim 4
Dependent Claim
67 words
0<R5,2/R5,3<1.6 1.4<(D5F-D5R)/fw<1.75 where f4 and f5F are focal lengths of said fourth lens group and said front lens group respectively, (D5F-D5R) is an axial air separation between said front lens group and said rear lens group, R5,i is a radius of curvature of the i-th lens surface counting from front in said fifth lens group, and fw is the shortest focal length of the entire lens system.
Claim 5
Dependent Claim
22 words
A zoom lens according to claim 1, wherein an aspheric surface is applied to said first lens of said front lens group.
Claim 6
Dependent Claim
21 words
A zoom lens according to claim 1, wherein said first lens group moves along the optical axis when focusing is performed.