Abstract: The zoom lens forms an intermediate image at a position conjugate to a reduction side imaging plane and forms the intermediate image again on a magnification side imaging plane. The zoom lens includes: a first optical system on the magnification side; and a second optical system on the reduction side. The intermediate image is formed between the magnification side and the reduction side. The second optical system includes two or more movable lens groups, which move by changing spacings between the groups adjacent to each other in a direction of an optical axis during zooming, and two stationary lens groups which remain stationary with respect to the reduction side imaging plane during zooming. One stationary lens group of the two stationary lens groups is disposed to be closest to the reduction side, and has a positive refractive power. In addition, a lens group closest to the magnification side in the second optical system has a positive refractive power.

Abstract: The wide-angle lens forms an intermediate image at a position conjugate to a reduction side imaging plane and forms the intermediate image again on a magnification side imaging plane. The wide-angle lens includes: a first optical system on the magnification side; and a second optical system on the reduction side. The intermediate image is formed between the magnification side and the reduction side. The first optical system has an optical axis deflection prism which satisfies predetermined conditional expressions.

Abstract: A zoom lens forms an intermediate image at a position conjugate to a reduction side imaging plane and forms the intermediate image again on a magnification side imaging plane. The zoom lens includes a plurality of lens groups including at least two movable lens groups, which move by changing spacings between the groups adjacent to each other in a direction of an optical axis during zooming, at a position closer to the reduction side than the intermediate image. Among the plurality of lens groups, a final lens group closest to the reduction side has a positive refractive power, and remains stationary with respect to the reduction side imaging plane during zooming. The zoom lens satisfies predetermined conditional expressions (1) and (2).

Abstract: In the zoom lens, a first optical system is formed on the magnification side, and a second optical system is formed on the reduction side, with the intermediate image formed between the first optical system and the second optical system. The second optical system consists of, in order from the magnification side, a first lens group that has a positive power, a second lens group that has a positive power, a third lens group that has a positive or negative power, and a fourth lens group that has a positive power. During zooming, the second lens group and the third lens group are moved by changing spacings between the groups adjacent to each other in a direction of an optical axis, and the fourth lens group remains stationary with respect to the reduction side imaging plane.

Abstract: The zoom lens forms an intermediate image at a position conjugate to a reduction side imaging plane and forms the intermediate image again on a magnification side imaging plane. The zoom lens includes: a first optical system on the magnification side; and a second optical system on the reduction side. The intermediate image is formed between the magnification side and the reduction side. The second optical system includes two or more movable lens groups, which move by changing spacings between the groups adjacent to each other in a direction of an optical axis during zooming, and one or more stationary lens groups which remain stationary with respect to the reduction side imaging plane during zooming. In addition, the movable lens groups are disposed to be adjacent to both the magnification side and the reduction side of the stationary lens group closest to the magnification side in the second optical system.

Abstract: The imaging optical system consists of a first optical system and a second optical system in order from a magnified side. The second optical system forms an image on an image display surface as an intermediate image, and the first optical system forms the intermediate image on a magnified-side conjugate plane. A height of a principal ray of light having a maximum angle of view becomes maximum on a lens surface of the whole system on the most magnified side, among heights of principal rays of light having a maximum angle of view on respective lens surfaces, to satisfy the following predetermined Conditional Expressions (1) and (2). 0.03<H×|f|/(L×I)<0.09 ??(1) 0.

Abstract: The imaging optical system consists of a first optical system and a second optical system in order from a magnified side. The first optical system consists of a 1a lens group, first optical path bending means, and a 1b lens group in order from the magnified side, and the second optical system consists of a 2a lens group, second optical path bending means, and a 2b lens group in order from the magnified side. The second optical system forms an image on an image display surface as an intermediate image, and the first optical system forms the intermediate image on a magnified-side conjugate plane, to satisfy the following predetermined Conditional Expression (1).

Abstract: A projection lens includes a compound aspherical lens in which a resin layer is formed on a surface of a glass lens and a lens surface of the resin layer on the air contacting surface side has an aspherical shape. If the glass transition temperature of the resin layer is taken as Tg and its unit is taken as ° C., Tg of at least one of the resin layers is 150<Tg<280. The projection lens is configured to satisfy a given conditional expression with respect to the at least one of the resin layers.

Abstract: A projection zoom lens includes: a first lens group having a negative refractive power provided most toward the magnification side, which is fixed when changing magnification; and at least two movable lens groups that move to change the relative distance therebetween in the direction of an optical axis when changing magnification. The first lens group is constituted by, in order from the magnification side to the reduction side, a front group having a negative refractive power and a rear group having a negative refractive power. The front group is fixed and only the rear group moves in the direction of the optical axis during focusing operations. Conditional Formula (1) related to the focal length f1a of the front group and the focal length f1b of the rear group is satisfied: f1b/f1a<0.8??(1).

Abstract: The projection zoom lens essentially consists of a positive first lens group fixed while changing magnification and the second lens group through the fourth lens group which move while changing magnification, and a fifth lens group fixed while changing magnification; and an aperture stop positioned between adjacent moving lens groups or within one moving lens group, wherein the numerical number of the zoom lens is set to be constant over the entire zoom range, the reduction side is configured to be telecentric, and the projection zoom lens satisfies conditional formulas (4) and (5): 2.0<Bf/Im???(4) L/Im?<12??(5), where, Bf: the back focus (air converted length) at the reduction side of the entire system at the wide angle end, Im?: the maximum effective image circle diameter, and L: the distance between the most-magnification-side lens surface and the most-reduction-side lens surface along the optical axis when the projection distance is infinite.

Abstract: A projection zoom lens includes: a first lens group having a negative refractive power provided most toward the magnification side, which is fixed when changing magnification; and at least two movable lens groups that move to change the relative distance therebetween in the direction of an optical axis when changing magnification. The first lens group is constituted by, in order from the magnification side to the reduction side, a front group which is fixed during focusing operations and a rear group having a negative refractive power that moves in the direction of the optical axis during focusing operations. The front group moves in the direction of the optical axis to correct field curvature. Conditional Formula (1) related to the focal length fw of the entire lens system at the wide angle end and the focal length fla of the front group is satisfied. |fw/fla|<0.2??(1).

Abstract: A projection zoom lens constituted by: a negative first lens group; a positive final lens group; and moving lens groups between the first and the final lens groups that move independently while changing magnification, satisfies the conditional formulae below: 1.00<(Rf2?Rr2)/(Rf2+Rr2)??(1) 0.00?(Rr2?Rf3)/(Rr2+Rf3)<0.15??(2) 2.5<Bf/Im???(9) wherein Rf2 and Rr2 respectively are the radii of curvature of the front and rear surfaces of the second lens from the magnification side within the most reduction side moving lens group, Rf3 is the radius of curvature of the front surface of the third lens from the magnification side within the most reduction side moving lens group, Bf is the back focus of the entire system at the reduction side at the wide angle end as an air converted length, and Im? is the maximum effective image circle diameter at the reduction side.

Abstract: A projection zoom lens is constituted by: a negative first lens group; a positive moving second lens group; a positive moving third lens group; a positive final lens group; at least one lens group positioned between the final lens group and the third lens group; and an aperture stop provided between adjacent moving lens groups. The aperture stop is a variable stop, of which the aperture diameter changes such that the numerical aperture of the zoom lens becomes constant. The zoom lens satisfies Conditional Formulae below: 2.8<Bf/Im???(1?) L/Im?<12??(2) wherein Bf is the back focus of the entire system at the reduction side at the wide angle end, Im? is the maximum effective image circle diameter at the reduction side, and L is the distance from the lens surface most toward the magnification side to the lens surface most toward the reduction side when the projection distance is infinity.

Abstract: A zoom lens consists essentially of, in order from the object side: a positive first lens group that is fixed during magnification change; a moving lens group consisting of at least two lens groups that are moved along the optical axis direction to change an air space therebetween during magnification change; a stop; and a positive end lens group that is fixed during magnification change. The first lens group consists of, in order from the object side, a negative first lens-group front group, a positive first lens-group middle group, and a positive first lens-group rear group. During focusing, only the first lens-group middle group is moved along the optical axis direction. The first lens-group middle group includes at least one aspheric lens that satisfies predetermined condition expressions.

Abstract: A projection zoom lens includes: a first lens group having a negative refractive power provided most toward the magnification side, which is fixed when changing magnification; and at least two movable lens groups that move to change the relative distance therebetween in the direction of an optical axis when changing magnification. The first lens group is constituted by, in order from the magnification side to the reduction side, a front group which is fixed during focusing operations and a rear group having a negative refractive power that moves in the direction of the optical axis during focusing operations. The front group moves in the direction of the optical axis to correct field curvature. Conditional Formula (1) related to the focal length fw of the entire lens system at the wide angle end and the focal length fla of the front group is satisfied. |fw/fla|<0.

Abstract: A projection zoom lens includes: a first lens group having a negative refractive power provided most toward the magnification side, which is fixed when changing magnification; and at least two movable lens groups that move to change the relative distance therebetween in the direction of an optical axis when changing magnification. The first lens group is constituted by, in order from the magnification side to the reduction side, a front group having a negative refractive power and a rear group having a negative refractive power. The front group is fixed and only the rear group moves in the direction of the optical axis during focusing operations. Conditional Formula (1) related to the focal length f1a of the front group and the focal length f1b of the rear group is satisfied: f1b/f1a<0.8 ??(1).

Abstract: A projection zoom lens essentially consists of a negative first lens group, a positive second lens group through the fourth lens group that move along the optical axis while changing magnification, a fifth lens group that moves while changing magnification, and a positive sixth lens group disposed in this order from the magnification side, wherein the projection zoom lens satisfies conditional formulas (1) and (2) below: 1.9<m4/fw??(1) 0.7<(m3+m4)/(m2+m3+m4+m5)??(2), where, mk (k=2 through 5) is the absolute value of movement of the k-th lens group while changing magnification from the wide angle end to the telephoto end, and fw: the focal length of the entire system at the wide angle end.

Abstract: A zoom lens consists essentially of, in order from the object side, a positive first lens group, a positive second lens group, a negative third lens group, a negative fourth lens group, and a positive fifth lens group. During magnification change from the wide-angle end to the telephoto end, the first lens group and the fifth lens group are fixed relative to the image plane, and the second lens group, the third lens group, and the fourth lens group are moved along the optical axis direction to change distances between the lens groups.

Abstract: In an optical system composed of, in order from the object side, an objective optical system and a reflective surface optical system disposed along the optical axis of the objective optical system, a first reflective surface is turned around a turning axis passing through the intersection between the first reflective surface and the optical axis and is perpendicular to the plane that includes the optical axes before and after being bent by the first reflective surface. Further, the first reflective surface and the second reflective surface are turned synchronously around turning axes, each passing through the intersection between each corresponding reflective surface with the optical axis, being deviated from the normal to each corresponding reflective surface, and being arranged in parallel to each other, whereby an image formed by the objective optical system is shifted to move the image location of the objective optical system.

Abstract: A variable magnification optical system for projection consists of a negative lens group and a positive lens group in this order from a magnification side. A distance on an optical axis between the negative lens group and the positive lens group changes during magnification change, and an entire system substantially consists of six lenses. The negative lens group consists of a first lens including an aspheric surface and a second lens that is a negative single lens in this order from the magnification side.