A lens attachment module is configured for coupling with a zoom module of a finite conjugate optical assembly. The lens attachment module includes a lens assembly that has a positive focal length, and exhibits a pupil size of between 16 and 25 mm and a pupil depth greater than 50 mm.

The imaging lens consists of, in order from the object side, a first lens group having a positive refractive power, a second lens group, and a third lens group. In the second lens group, a first focus lens group having a negative refractive power is disposed to be closest to the object side, and a second focus lens group having a positive refractive power is disposed to be closest to the image side. During focusing, only the first and second focus lens groups move by changing the mutual spacing therebetween. The first lens group has two positive lenses and one negative lens. The first focus lens group consists of two or less lenses including a negative lens. Predetermined conditional expressions are satisfied.

The zoom lens consists of, in order from an object side: a positive first lens group that does not move during zooming; a middle group that consists of two or more movable lens groups moving during zooming; and a subsequent group that has a lens group including a stop at a position closest to the object side. The middle group has at least two negative movable lens groups. The subsequent group includes at least one positive LA lens that satisfies predetermined conditional expressions relating to the refractive index, the Abbe number, and the partial dispersion ratio.

The zoom lens consists of, in order from an object side: a positive first lens group that does not move during zooming; a middle group that consists of two or more movable lens groups moving during zooming; and a subsequent group that has a lens group including a stop at a position closest to the object side. The middle group has at least two negative movable lens groups. At least one negative movable lens group in the middle group includes at least one negative LN lens which satisfies predetermined conditional expressions relating to the refractive index, the Abbe number, and the partial dispersion ratio.

A projection optical device includes a fourth lens group movable along an optical axis, a fifth lens group provided in a position maintained within the projection optical device, a fourth lens frame holding the fourth lens group and having cam pins, a guide tube having a rectilinear groove, the cam pins inserted into the rectilinear groove, and a cam tube rotated with respect to the guide tube to guide the cam pins with the rectilinear groove and the cam groove, and moving the fourth lens frame along the optical axis, wherein the cam pins are formed on an upstream side in an optical path of the fourth lens group in a direction along the optical axis, and the fifth lens group is provided on the upstream side in the optical path of the fourth lens group.

A lens module is provided, including: a lens barrel including first and second barrel walls; and a set of lenses received in the lens barrel and including at least a first lens and a second lens arranged from an object side to an image side. The first lens includes a first optical portion and a first peripheral portion surrounding the first optical portion. A surface of the first barrel wall close to the image side includes a first planar surface extending horizontally towards an optical axis from a position where the first barrel wall is connected to the second barrel wall; a first oblique surface extending obliquely from the first planar surface towards the optical axis and towards the image side; and a second planar surface extending horizontally from the first oblique surface towards the optical axis.

A lens module is provided, including: a lens barrel including first and second barrel walls; and a set of lenses received in the lens barrel and including at least a first lens and a second lens arranged from an object side to an image side. The first lens includes a first optical portion and a first peripheral portion surrounding the first optical portion. A surface of the first barrel wall close to the image side includes a first planar surface extending horizontally towards an optical axis from a position where the first barrel wall is connected to the second barrel wall; a first oblique surface extending obliquely from the first planar surface towards the optical axis and towards the image side; and a second planar surface extending horizontally from the first oblique surface towards the optical axis.

Provided is a lens module, including a lens barrel; and a set of lenses received in the lens barrel. The set of lenses at least includes first and second lenses. The first and second lenses cooperate with each other in a direction from an object side to an image side. A surface of the first lens facing towards the second lens includes a first abutting surface extending horizontally toward an optical axis, and a first oblique surface extending obliquely from the first abutting surface in a direction facing towards the optical axis and towards the object side. The second lens includes a second abutting surface attached to the first abutting surface, and a second oblique surface extending obliquely from the second abutting surface in the direction facing towards the optical axis and towards the object side. The first oblique surface is spaced apart from the second oblique surface.

Provided is a lens module, including a lens barrel; and a set of lenses received in the lens barrel. The set of lenses at least includes first and second lenses. The first and second lenses cooperate with each other in a direction from an object side to an image side. A surface of the first lens facing towards the second lens includes a first abutting surface extending horizontally toward an optical axis, and a first oblique surface extending obliquely from the first abutting surface in a direction facing towards the optical axis and towards the object side. The second lens includes a second abutting surface attached to the first abutting surface, and a second oblique surface extending obliquely from the second abutting surface in the direction facing towards the optical axis and towards the object side. The first oblique surface is spaced apart from the second oblique surface.

Provided are an imaging apparatus, a signal processing method for an imaging apparatus, and a non-transitory computer readable recording medium storing a signal processing program for an imaging apparatus capable of capturing a high quality image with a compact configuration. An imaging lens 10A is composed of, in order from an object side, a first lens group G1 that is fixed during variable magnification, a second lens group G2 and a third lens group G3 that move during variable magnification, and a fourth lens group G4 that is fixed during variable magnification. The first lens group G1 is composed, in order from the object side, a first-a lens group G1a that is fixed during focusing, a first-b lens group G1b that moves during focusing, and a first lens group rear group G1c that is fixed during focusing. Fluctuation of an angle of view with focusing is corrected through image processing.