Large caliber standard lens

A standard lens comprising:

• a first lens of a positive refractive power;
• a second lens of a negative refractive power;
• an aperture diaphragm;
• a third lens of a negative refractive power;
• a fourth lens of a positive refractive power;
• and
• a fifth lens of a positive refractive power,
• wherein the first lens, the second lens, the diaphragm, the third lens, the fourth lens, and the fifth lens are arranged sequentially from an object side to an image side, and the first lens, the second lens, the third lens, and the fourth lens are meniscus lenses having concave surfaces facing the diaphragm and satisfy the following inequality,
• 0.6
• ≤
• 
• R
• 6
• R
• 4
• 
• ≤
• 1.0
• where R4 denotes the radius of curvature of the surface of the second lens facing the image side, and R6 is the radius of curvature of the surface of the third lens facing the object.