Single-focus lens

A single-focus lens consisting of:

• consecutively from an object side,
• a first lens having a meniscus shape and a positive refractive power;
• a second lens having a meniscus shape and including at least one aspheric surface;
• a third lens directing its convex surface to an image side and having a positive refractive power;
• and
• a fourth lens having a meniscus shape, including at least one aspheric surface, and directing its concave surface to the image side.

A single-focus lens, comprising:

• consecutively from an object side,
• a first lens having a meniscus shape and a positive refractive power;
• a second lens having a meniscus shape and including at least one aspheric surface;
• a third lens directing its convex surface to an image side and having a positive refractive power;
• and
• a fourth lens having a meniscus shape, including at least one aspheric surface, and directing its concave surface to the image side, wherein conditional expressions (13), (14) and (15) below are satisfied
• 1.70<Nd1 (13)
• 35>νd1 (14)
• 50>νd3 (15)
• where the Nd1 represents refractive index of the first lens for a wavelength of d-line, the νd1 represents Abbe number of the first lens for the wavelength of d-line and the νd3 represents Abbe number of the third lens for the wavelength of d-line.

A single-focus lens, comprising:

• consecutively from an object side,
• a first lens having a meniscus shape and a positive refractive power;
• a second lens having a meniscus shape and including at least one aspheric surface;
• a third lens directing its convex surface to an image side and having a positive refractive power;
• and
• a fourth lens having a meniscus shape, including at least one aspheric surface, and directing its concave surface to the image side, and
• wherein the second lens and the fourth lens are made of optical plastic and conditional expressions (13), (14) and (15) below are satisfied
• 1.70<Nd1 (13)
• 35>νd1 (14)
• 50<νd3 (15)
• where the Nd1 represents refractive index of the first lens for a wavelength of d-line, the νd1 represents Abbe number of the first lens for the wavelength of d-line and the νd3 represents Abbe number of the third lens for the wavelength of d-line.

A single-focus lens, comprising:

• consecutively from an object side,
• a first lens having a meniscus shape and a positive refractive power;
• a second lens having a meniscus shape and including at least one aspheric surface;
• a third lens directing its convex surface to an image side and having a positive refractive power;
• and
• a fourth lens having a meniscus shape, including at least one aspheric surface, and directing its concave surface to the image side, and
• wherein conditional expressions (11) and (12) below are satisfied
• −0.2<f/f2<0.2 (11)
• −0.2<f/f4<0.2 (12)
• where the f represents an overall focal length;
• the f2 represents a focal length of the second lens;
• and the f4 represents a focal length of the fourth lens;
• and
• wherein conditional expressions (13), (14) and (15) below are satisfied
• 1.70<Nd1 (13)
• 35>νd1 (14)
• 50<νd3 (15)
• wherein the Nd1 represents refractive index of the first lens for a wavelength of d-line, the νd1 represents the Abbe number of the first lens for the wavelength of d-line and the νd3 represents Abbe number of the third lens for the wavelength of d-line.