Lens component, image forming optical system, and electronic image pickup apparatus using the same

A lens component which is a cemented lens comprising:

• a lens LA;
• and
• a lens LB, wherein
• an absolute value of a refracting power of the lens LB is smaller than an absolute value of a refracting power of the lens LA, and the lens component satisfies the following conditional expressions (1) and (3)
• 0.01≦1/ν2−1/ν1≦0.06 (1)
• 0.5×ν2/ν1<Tν2/Tν1<10×ν2/ν1 (3)
• where,
• ν1 denotes Abbe's number (nd1−1)/(nF1−nC1) of the lens LA,
• ν2 denotes Abbe's number (nd2−1)/(nF2−nC2) of the lens LB,
• nd1, nC1, nF1, and ng1 denote refractive indices of the lens LA for a d-line, a C-line, an F-line, and a g-line respectively,
• nd2, nC2, nF2, and ng2 denote refractive indices of the lens LB for the d-line, the c-line, the F-line, and the g-line respectively,
• Tν1 denotes a reciprocal of a temperature dispersion of the lens LA,
• Tν2 is a reciprocal of a temperature dispersion of the lens LB, and
• a reciprocal Tνd of the temperature dispersion is expressed by the following expression
• Tνd=(nd20−1)/(nd00−nd40)
• where,
• nd00 is a refractive index of the d-line of a lens medium at 0° C.,
• nd20 is a refractive index of the d-line of the lens medium at 20° C., and
• nd40 is a refractive index of the d-line of the lens medium at 40° C.