Abstract: A lens unit includes a guided portion that includes a first bearing portion and a second bearing portion disposed to be spaced apart from each other in a direction X and is slidably supported by a guide shaft, and a lens holding member. A first distance between the center of a fixing portion of the lens holding member and the center of the first bearing portion in the direction X is set to be longer than a second distance between the center of the fixing portion and the center of the second bearing portion in the direction X. A first tilt-preventing member having a linear expansion coefficient lower than that of the lens holding member is fixed to a region, which is closer to the first bearing portion than the center of the fixing portion, of a portion of the guided portion positioned between the first and second bearing portions.

Abstract: The zoom lens consists of, in order from the object side, a first lens group that has a negative refractive power; a second lens group that has a positive refractive power; a third lens group that has a negative refractive power; and a fourth lens group that has a positive refractive power. During zooming, in each lens group, distances between the adjacent groups in the direction of the optical axis are changed. The first lens group consists of, in order from the object side, a first lens having a negative refractive power, a second lens having a negative refractive power, and a third lens having a positive refractive power. The third lens group consists of a negative lens. During focusing, only the third lens group moves along the optical axis. The zoom lens satisfies predetermined conditional expressions.

Abstract: The zoom lens consists of, in order from the object side, a first lens group that has a negative refractive power; a second lens group that has a positive refractive power; a third lens group that has a negative refractive power; and a fourth lens group that has a positive refractive power. During zooming, in each lens group, distances between the adjacent groups in the direction of the optical axis are changed. The first lens group consists of, in order from the object side, a first lens having a negative refractive power, a second lens having a negative refractive power, and a third lens having a positive refractive power. The third lens group consists of a negative lens. During focusing, only the third lens group moves along the optical axis. The zoom lens satisfies predetermined conditional expressions.

Abstract: The imaging lens includes, as lens groups, only a positive first lens group, a positive second lens group, and a negative third lens group in order from the object side. An aperture stop is disposed between a lens surface closest to the image side in the first lens group and a lens surface closest to the object side in the third lens group. During focusing, the first lens group and the third lens group do not move, and the second lens group moves. The first lens group consists of a negative lens and a positive lens in order from the object side. The third lens group has a negative lens and a positive lens in order from the object side.

Abstract: The imaging lens consists of, in order from an object side, a positive first lens group, a positive second lens group, and a negative third lens group. During focusing, only the second lens group moves. The number of lenses included in the second lens group is two or less. The lens on the most object side is a negative lens having a convex surface toward the object side. The lens surface on the most image side is a convex surface. The first lens group includes a stop. Predetermined conditional expressions related to the first lens group and the second lens group are satisfied.

Abstract: The zoom lens consists of, in order from the object side, a first lens group that has a negative refractive power; a second lens group that has a positive refractive power; a third lens group that has a negative refractive power; and a fourth lens group that has a positive refractive power. During zooming, in each lens group, distances between the adjacent groups in the direction of the optical axis are changed. The first lens group consists of, in order from the object side, a first lens having a negative refractive power, a second lens having a negative refractive power, and a third lens having a positive refractive power. The third lens group consists of a negative lens. During focusing, only the third lens group moves along the optical axis. The zoom lens satisfies predetermined conditional expressions.

Abstract: The imaging lens consists of, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power. The first lens group has a positive lens, a positive lens, and a negative lens successively in order from a position closest to the object side. The second lens group consists of one negative lens. The third lens group includes two or less lenses. During focusing, only the second lens group moves. The following conditional expression, which relates to a focal length f of the whole system in a state where the object at infinity is in focus and a focal length f2 of the second lens group, is satisfied: 0.4<|f/f2|<1.3.

Abstract: An imaging lens includes, in order from the object side to the image side, a positive first lens group, a stop, a positive second lens group, and a positive third lens group. The first lens group includes, consecutively in order from the most object side thereof, a negative lens and a positive lens. The second lens group is of a three lens configuration and includes a positive lens and a negative lens. The third lens group includes, consecutively in order from the most object side thereof, a negative lens and a positive lens. The imaging lens satisfies Conditional Formula (1): 0<f1/f2<2, which is related to the focal length f1 of the first lens group and the focal length f2 of the second lens group.

Abstract: The imaging lens consists of, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power. The first lens group has a positive lens, a positive lens, and a negative lens successively in order from a position closest to the object side. The second lens group consists of one negative lens. The third lens group includes two or less lenses. During focusing, only the second lens group moves. The following conditional expression, which relates to a focal length f of the whole system in a state where the object at infinity is in focus and a focal length f2 of the second lens group , is satisfied: 0.4<|f/f2|<1.3.

Abstract: An imaging lens includes, in order from the object side to the image side, a positive first lens group, a stop, a positive second lens group, and a positive third lens group. The first lens group includes, consecutively in order from the most object side thereof, a negative lens and a positive lens. The second lens group is of a three lens configuration and includes a positive lens and a negative lens. The third lens group includes, consecutively in order from the most object side thereof, a negative lens and a positive lens. The imaging lens satisfies Conditional Formula (1): 0<f1/f2<2, which is related to the focal length f1 of the first lens group and the focal length f2 of the second lens group.