Taking lens system

A taking lens system of two-unit construction consisting of:

• a front lens unit including at least one positive lens and at least one negative lens whose image-side surface has a stronger curvature than that of an object-side surface thereof,
• a rear lens unit including a doublet which consists of a positive lens and a negative lens and which has a positive refractive power as a whole, and a positive lens, and
• a stop is located on the image side with respect to said front lens unit,
• wherein focusing from an infinite object point to a near object point is effected by varying the spacing between said front and rear lens units.

A taking lens system of two-unit construction consisting essentially of:

• a front lens unit including at least one positive lens and at least one negative lens whose image-side surface has a stronger curvature than that of an object-side surface thereof, and
• a rear lens unit including a doublet which consists of a positive lens and a negative lens and which has a positive refractive power as a whole, and a positive lens,
• wherein focusing from an infinite object point to a near object point is effected by varying the spacing between said front and rear lens units,
• wherein during focusing said front lens unit and said rear lens unit move on the optical axis while a spacing therebetween varies.

A taking lens systems of two-unit construction consisting essentially of:

• a front lens unit including at least one positive lens and at least one negative lens whose image-side surface has a stronger curvature than that of an object-side surface thereof, and
• a rear lens unit including a doublet which consists of a positive lens and a negative lens and which has a positive refractive power as a whole, and a positive lens,
• wherein focusing from an infinite object point to a near object point is effected by varying the spacing between said front and rear lens unit,
• wherein said front lens unit is a cemented lens.

A taking lens system comprising:

• a front lens unit including at least one positive lens and at least one negative lens whose image-side surface has a stronger curvature than that of an object-side surface thereof, and
• a rear lens unit disposed behind said front lens unit and including a cemented doublet which consists of one positive lens and one negative lens and which has a positive refractive power as a whole, and a positive lens,
• wherein a lens surface of said cemented doublet that is the closest to the image side is concave toward the image side, and an intermediate lens surface of said doublet is convex toward the image side,
• which satisfies the following condition (1):
• (1) 0.4f<.vertline.R.sub.N .vertline.
• wherein R.sub.N is the radius of curvature of the object-side lens surface of the negative lens in said front lens unit, and is the focal length of the entire lens system.

A taking lens system comprising:

• a front lens unit including at least one positive lens and at least one negative lens whose image-side surface has a stronger curvature than that of an object-side surface thereof, and
• a rear lens unit disposed behind said front lens unit and including a cemented doublet which consists of one positive lens and one negative lens and which has a positive refractive power as a whole, and a positive lens,
• wherein a lens surface of said cemented doublet that is the closest to the image side is concave toward the image side, and an intermediate lens surface of said doublet is convex toward the image side,
• which satisfies the following condition (2):
• (2) 0<f/f.sub.4 <0.85
• wherein f.sub.4 is the focal length of the positive lens group behind said doublet, and f is the focal length of the entire lens system.

A taking lens system comprising:

• a front lens unit including at least one positive lens and at least one negative lens whose image-side surface has a stronger curvature than that of an object-side surface thereof, and
• a rear lens unit disposed behind said front lens unit and including a cemented doublet which consists of one positive lens and one negative lens and which has a positive refractive power as a whole, and a positive lens,
• wherein a lens surface of said cemented doublet that is the closest to the image side is concave toward the image side, and an intermediate lens surface of said doublet is convex toward the image side,
• which satisfies the following condition (3):
• (3) 0.3/f<.vertline.(N.sub.a -N.sub.b)/R.sub.c .vertline.<1.5/f
• wherein N.sub.a is the refractive index of the positive lens of said doublet, N.sub.b is the refractive index of the negative lens of said doublet, R.sub.c is the radius of curvature of the cemented surface of said doublet, and f is the focal length of the entire lens system.

A taking lens system according to comprising:

• a front lens unit including at least one positive lens and at least one negative lens whose image-side surface has a stronger curvature than that of an object-side surface thereof, and
• a rear lens unit disposed behind said front lens unit and including a cemented doublet which consists of one positive lens and one negative lens and which has a positive refractive power as a whole, and a positive lens,
• wherein a lens surface of said cemented doublet that is the closest to the image side of concave toward the image side, and an intermediate lens surface of said doublet is convex toward the image side,
• which satisfies the following condition (4):
• (4) 0.01<.vertline.(f.sub.II /f.sub.I .vertline.<0.25
• where f.sub.I and f.sub.II are the focal lengths of said front and rear lens units, respectively.

A taking lens system comprising:

• a front lens unit including at least one positive lens and at least one negative lens whose image-side surface has a stronger curvature than that of an object-side surface thereof, and
• a rear lens unit disposed behind said front lens unit and including a cemented doublet which consists of one positive lens and one negative lens and which has a positive refractive power as a whole, and a positive lens,
• wherein a lens surface of said cemented doublet that is the closest to the image side is concave toward the image side, and an intermediate lens surface of said doublet is convex toward the image side,
• which satisfies the following condition (5):
• (5) 0.01<.vertline.(f/f.sub.I .vertline.<0.30
• where f.sub.I is the local length of said front lens unit, and f is the focal length of the entire lens system.

A taking lens system of two-unit construction consisting of:

• a front lens unit including at least one positive lens and at least one negative lens whose image-side surface has a stronger curvature than that of an object-side surface thereof, and
• a rear lens unit including a doublet which consists of a positive lens and a negative lens and which has a positive refractive power as a whole, and a positive lens,
• wherein focusing from an infinite object point to a near object point is effected by varying the spacing between said front and rear lens units,
• which satisfies the following condition (1):
• (1) 0.4f<.vertline.R.sub.N .vertline.
• wherein R.sub.N is the radius of curvature of the object-side lens surface of the negative lens in said front lens unit, and f is the focal length of the entire lens system.

A taking lens system of two-unit construction consisting of:

• a front lens unit including at least one positive lens and at least one negative lens whose image-side surface has a stronger curvature than that of an object-side surface thereof, and
• a rear lens unit including a doublet which consists of a positive lens and a negative lens and which has a positive refractive power as a whole, and a positive lens,
• wherein focusing from an infinite object point to a near object point is effected by varying the spacing between said front and rear lens units,
• which satisfies the following condition (2):
• (2) 0<f/f.sub.4 <0.85
• wherein f.sub.4 is the focal length of the positive lens group behind said doublet, and f is the focal length of the entire lens system.

A taking lens system of two-unit construction consisting of:

• a front lens unit including at least one positive lens and at least one negative lens whose image-side surface has a stronger curvature than that of an object-side surface thereof, and
• a rear lens unit including a doublet which consists of a positive lens and a negative lens and which has a positive refractive power as a whole, and a positive lens,
• wherein focusing from an infinite object point to a near object point is effected by varying the spacing between said front and rear lens units,
• which satisfies the following condition (3):
• (3) 0.3/f<.vertline.(N.sub.a -N.sub.b)/R.sub.c .vertline.<1.5/f
• wherein N.sub.a is the refractive index of the positive lens of said doublet, N.sub.b is the refractive index of the negative lens of said doublet, R.sub.c is the radius of curvature of the cemented surface of said doublet, and f is the focal length of the entire lens system.

A taking lens system of two-unit construction consisting of:

• a front lens unit including at least one positive lens and at least one negative lens whose image-side surface has a stronger curvature than that of an object-side surface thereof, and
• a rear lens unit including a doublet which consists of a positive lens and a negative lens and which has a positive refractive power as a whole, and a positive lens,
• wherein focusing from an infinite object point to a near object point is effected by varying the spacing between said front and rear lens units,
• which satisfies the following condition (4):
• (4) 0.01<.vertline.(f.sub.II /f.sub.I .vertline.<0.25
• where f.sub.I and f.sub.II are the focal lengths of said front and rear lens units, respectively.

A taking lens system of two-unit construction consisting of:

• a front lens unit including at least one positive lens and at least one negative lens whose image-side surface has a stronger curvature than that of an object-side surface thereof, and
• a rear lens unit including a doublet which consists of a positive lens and a negative lens and which has a positive refractive power as a whole, and a positive lens,
• wherein focusing from an infinite object point to a near object point is effected by varying the spacing between said front and rear lens units,
• which satisfies the following condition (5):
• (5) 0.01<.vertline.(f/f.sub.I .vertline.<0.30
• where f.sub.I is the local length of said front lens unit, and f is the focal length of the entire lens system.