Inverted telephoto type wide angle lens system

An inverted telephoto type wide angle lens system consisting, from the object to the image side, of:

• a first component of a positive meniscus lens element convex to the object side;
• a second component of a negative meniscus lens element convex to the object side;
• a third component of a negative meniscus lens element convex to the object side;
• a fourth component of a biconvex lens element;
• an aperture stop;
• a fifth component of a positive meniscus lens element convex to the object side;
• a sixth component of a biconvex lens element;
• a seventh component of a biconcave lens element;
• an eighth component of a positive meniscus lens element convex to the image side;
• and
• a ninth component of overall positive refractive power including at least one lens element.

An inverted telephoto type wide angle lens system comprising:

• an aperture stop;
• a first group of lens elements defined between a front surface of the lens system and a surface adjacent to the aperture stop at the object side thereof, and
• a second group of lens elements defined between a surface adjacent to the aperture stop at the image side thereof and a rear surface of the system, the second group including, next to the aperture stop, a positive meniscus lens element convex to the object side, a biconvex lens element next to the positive meniscus lens element at the image side thereof, the biconvex lens element being axially movable relative to the other lens elements in association with the focusing,
• wherein the lens system fulfulls the following conditions:
• f<r.sub.m <5f
• 0. 06f<d<0.02f
• 0.15f<X<0.4f
• 0.6f<f.sub.b <2.0f
• wherein r.sub.m represents a radius of curvature of an object side surface of the positive meniscus lens element;
• d represents an axial width of an air space next to the positive meniscus lens element at the image side thereof;
• X represents the maximum axial distance from the aperture stop to the object side surface of the biconvex lens element, f.sub.b represents a focal length of the biconvex lens element, and f represents a focal length of the whole lens system.

An inverted telephoto type wide angle lens system comprising:

• an aperture stop;
• a first group of lens elements, immovable relative to each other and defined between a front surface of the system and a surface adjacent to the aperture stop at the object side thereof, consisting, consecutively from the object to the image side, of a first negative sub-group including at least two negative meniscus lens elements each convex to the object side and a second sub-group including a positive lens element;
• and
• a second group of lens elements defined between a surface adjacent to the aperture stop at the image side thereof and a rear surface of the system, the second group including next to the aperture stop a positive meniscus lens element convex to the object side, the location of the positive meniscus lens element being unchangeable relative to the aperture stop upon focusing, and a plurality of lens elements succeeding the positive meniscus lens element at the image side thereof, the plurality of lens elements being of a positive refractive power on the whole and including a negative lens element and at least two positive lens elements at the image side of the negative lens element, wherein the air space between the positive meniscus lens element and the most object side lens element of the plurality of lens elements is changeable in association with a focusing mode of operation.

An inverted telephoto type wide angle lens system comprising:

• an aperture stop;
• a first group of lens elements defined between a front surface of the system and a surface adjacent to the aperture stop at the object side thereof, consisting, consecutively from the object to the image side, of a positive lens element, a first negative lens element a second negative lens element and a positive lens element, and a second group of lens elements defined between a surface adjacent to the aperture stop at the image side thereof and a rear surface of the system, the second group including, consecutively, next to the aperture stop a positive meniscus lens element convex to the object side, a first positive lens element, a negative lens element, a second positive lens element and a group of lenses of an overall positive refractive power consisting of at least one lens element wherein the lens system fulfills the following conditions:
• 1.5f<.vertline.f.sub.F .vertline.<3.0f, f.sub.F <0
• 3f<f.sub.m <12f
• f<r.sub.m <5f
• 0.06f<d<0.2f
• wherein
• f.sub.F represents an overall focal length of the first group;
• f.sub.m represents a focal length of the positive meniscus lens element;
• r.sub.m represents a radius of curvature of an object side surface of the positive meniscus lens element;
• d represents an axial width of an air space next to the positive meniscus lens element at the image side thereof, and
• f represents a focal length of the whole lens system.

An inverted telephoto type wide angle lens system comprising:

• an aperture stop;
• a first group of lens elements defined between a front surface of the system and a surface adjacent to the aperture stop at the object side thereof, and
• a second group of lens elements defined between a surface adjacent to the aperture stop at the image side thereof and a rear surface of the system, the second group including next to the aperture stop a positive meniscus lens element convex to the object side, and a biconvex lens element next to the positive meniscus lens element at the image side thereof, the biconvex lens element being axially movable relative to the other lens elements in association with the focusing, wherein the lens system fulfills the following conditions:
• 1.5f<f.sub.F <3.0f, f.sub.F <0
• 3f<f.sub.m <12f
• f<r.sub.m <5f
• 0.06f<d<0.2f
• 0.15f<X<0.4f
• 0.6f<f.sub.b <2.0f
• wherein
• f.sub.F represents an overall focal length of the first group;
• f.sub.m represents a focal length of the positive meniscus lens element;
• r.sub.m represents a radius of curvature of an object side surface of the positive meniscus lens element;
• d represents an axial width of an air space next to the positive meniscus lens element at the image side thereof;
• X represents the maximum axial distance from the aperture stop to the object side surface of the biconvex lens element;
• f.sub.b represents a focal length of the biconvex lens element, and
• f represents a focal length of the whole lens system.