Image pickup apparatus

An image pickup apparatus, comprising:

• an image forming optical system which includes an aperture stop which determines an axial light beam, and a plurality of lens components, and
• an image pickup section which is disposed on an image side of the image forming optical system, and has a light-receiving surface which is not flat but is curved to be concave toward the image forming optical system,
• wherein:
• the lens component is a lens having only two surfaces in contact with air on an optical axis, which are an object-side surface and an image-side surface,
• the image forming optical system includes, in order from an object side to the image side, a first lens component having a negative refractive power, a second lens component having a positive refractive power, and a third lens component having a positive refractive power,
• in the first lens component, a lens surface on the object side is convex toward the object side,
• in a lens surface on the object side of the second lens component, a part of an area is concave toward the object side, and
• the following conditional expressions (1) and (4) are satisfied:
• 0.5<(R1L+R1R)/(R1L−R1R)<2.5 (1),
• and
• 0.6<|(Y1×2)/Rimg|<3 (4)
• where,
• R1L denotes a paraxial radius of curvature of the lens surface on the object side, of the first lens component,
• R1R denotes a paraxial radius of curvature of a lens surface on the image side, of the first lens component,
• Y1 denotes a maximum light-ray height in a predetermined area,
• the predetermined area is an area on the lens surface on the object side of the first lens component, through which an effective light beam passes, and
• Rimg denotes a radius of curvature of a virtual spherical surface which includes a surface apex and a point in which a principal light ray incident at the maximum angle of view on the image forming optical system intersects a light-receiving surface, letting a point of intersection of the optical axis and the light-receiving surface to be the surface apex.

An image pickup apparatus, comprising:

• an image forming optical system which includes an aperture stop which determines an axial light beam, and a plurality of lens components, and
• an image pickup section which is disposed on an image side of the image forming optical system, and has a light-receiving surface which is not flat but is curved to be concave toward the image forming optical system,
• wherein:
• the lens component is a lens having only two surfaces in contact with air on an optical axis, which are an object-side surface and an image-side surface,
• the image forming optical system includes, in order from an object side to the image side, a first lens component having a negative refractive power, a second lens component having a positive refractive power, and a third lens component having a positive refractive power,
• in the first lens component, a lens surface on the object side is convex toward the object side,
• in a lens surface on the object side of the second lens component, a part of an area is concave toward the object side, and
• the following conditional expressions (1) and (5) are satisfied:
• 0.5<(R1L+R1R)/(R1L−R1R)<2.5 (1),
• and
• 0.5<|EXP/Rimg|≤1 (5)
• where,
• R1L denotes a paraxial radius of curvature of the lens surface on the object side, of the first lens component,
• R1R denotes a paraxial radius of curvature of a lens surface on the image side, of the first lens component,
• EXP denotes a distance along the optical axis from the light-receiving surface up to a paraxial exit-pupil position of the image forming optical system, and a sign when the paraxial exit-pupil position is on the object side of the light-receiving surface is let to be negative, and
• Rimg denotes a radius of curvature of a virtual spherical surface which includes a surface apex and a point in which a principal light ray incident at the maximum angle of view on the image forming optical system intersects a light-receiving surface, letting a point of intersection of the optical axis and the light-receiving surface to be the surface apex.

An image pickup apparatus, comprising:

• an image forming optical system which includes an aperture stop which determines an axial light beam, and a plurality of lens components, and
• an image pickup section which is disposed on an image side of the image forming optical system, and has a light-receiving surface which is not flat but is curved to be concave toward the image forming optical system,
• wherein:
• the lens component is a lens having only two surfaces in contact with air on an optical axis, which are an object-side surface and an image-side surface,
• the image forming optical system includes, in order from an object side to the image side, a first lens component having a negative refractive power, a second lens component having a positive refractive power, and a third lens component having a positive refractive power,
• in the first lens component, a lens surface on the object side is convex toward the object side,
• in a lens surface on the object side of the second lens component, a part of an area is concave toward the object side, and
• the following conditional expressions (1), (6), and (7) are satisfied:
• 0.5<(R1L+R1R)/(R1L−R1R)<2.5 (1),
• 180°≤2ω≤230° (6),
• and
• 1.7≤Fno≤6.0 (7)
• where,
• R1L denotes a paraxial radius of curvature of the lens surface on the object side, of the first lens component,
• R1R denotes a paraxial radius of curvature of a lens surface on the image side, of the first lens component,
• ω denotes a maximum half angle of view, and
• Fno denotes an F-number.