Wide-angle lens

A wide-angle lens consisting of:

• a first lens group comprising a lens having a negative refractive power as a whole,
• a second lens group including an optical element,
• a third lens group comprising up to two lenses having a positive refractive power and
• a fourth lens group comprising one lens having a negative refractive power in order of an optical path from an object side,
• wherein the first lens group includes a meniscus lens having a negative refractive power and a convex surface facing the object side,
• the optical element has, in the order of the optical path, a first optical surface that is convex toward the object side, a second optical surface that bends the optical path from the first optical surface and a third optical surface that is concave toward the object side, and
• the first optical surface, the second optical surface and the third optical surface are integrally molded,
• wherein the wide-angle lens has six or more aspherical surfaces in total, and
• wherein the wide-angle lens satisfies the following conditional expression (1)
• 0.35
• <
• f
• /
• (
• FNo
• ×
• d
• ⁢
• 2
• )
• <
• 1.
• (
• 1
• )
• here,
• f is a focal length of the entire wide-angle lens,
• FNo is an F number of the wide-angle lens, and
• d2 is a thickness of the entire second lens group on an optical axis.

A wide-angle lens consisting of:

• a first lens group comprising a lens having a negative refractive power as a whole,
• a second lens group including an optical element,
• a third lens group comprising up to two lenses having a positive refractive power and
• a fourth lens group comprising one lens having a negative refractive power in order of an optical path from an object side,
• wherein the first lens group includes a meniscus lens having a negative refractive power and a convex surface facing the object side,
• the optical element has, in the order of the optical path, a first optical surface that is convex toward the object side, a second optical surface that bends the optical path from the first optical surface and a third optical surface that is concave toward the object side, and
• the first optical surface, the second optical surface and the third optical surface are integrally molded,
• wherein the wide-angle lens has six or more aspherical surfaces in total, and
• wherein the wide-angle lens satisfies the following conditional expression (5)
• -
• 0
• .
• 8
• ⁢
• 0
• <
• f
• /
• fL
• ⁢
• 4
• <
• -
• 0
• .
• 1
• ⁢
• 5
• (
• 5
• )
• here,
• f is a focal length of the entire wide-angle lens, and
• fL4 is a focal length of the fourth lens group.