Single focal length lens system, camera, and automobile

A single focal length lens system, in order from an object side to an image side, comprising:

• a first unit;
• an aperture diaphragm;
• and a second unit, wherein
• the first unit includes a lens element made of glass at a position closest to the object side,
• the second unit includes a cemented lens having positive optical power, and a joint surface of the cemented lens is an aspheric surface, and
• the following conditions (1), (2) and (3) are satisfied:
• |dn/dt1|MAX≦2.67×10−5 (1)
• 2ωDIA≧150 (2)
• 2.0<fCEM/f<4.0 (3)
• where
• |dn/dt1|MAX is a maximum value of absolute values of relative refractive index temperature coefficients in an atmosphere at 0 to 20° C. with respect to light having a wavelength range of 580 to 640 nm, which is calculated for each of lens elements constituting the cemented lens,
• 2ωDIA is a diagonal angle of view)(°),
• fCEM is a focal length at d-line of the cemented lens, and
• f is a focal length at d-line of the entire system.