Large aperture ratio, long focus lens

A compact, large aperture ratio, long focus lens having a short total length and in which various aberrations, particularly, annular spherical aberration and chromatic aberration of spherical aberration, are well corrected, including, in succession from the object side:

• a first group comprising a positive meniscus lens having its convex surface facing the object side;
• a second group comprising a positive meniscus lens having its convex surface facing the object side;
• a third group comprising a negative meniscus lens consisting of a biconvex lens and a biconcave lens cemented thereto and having its convex surface facing the object side, the dispersion of said biconvex lens being greater than that of said biconcave lens;
• a diaphragm;
• a fourth group comprising a meniscus lens consisting of a negative lens and a positive lens cemented thereto and having its convex surface facing the image side;
• and
• a fifth group comprising a positive lens;
• said second group and said third group forming therebetween an air lens having a divergent refractive power.