Optical system, optical apparatus and method for manufacturing the optical system, and zoom optical system, optical apparatus and method for manufacturing the zoom optical system

A method for manufacturing an optical system, the method comprises a step of arranging, in a lens barrel, an aperture stop and a cemented lens including a positive lens, the positive lens being one of two lenses cemented to each other to form the cemented lens, the positive lens being disposed closer to an object than the aperture stop, the positive lens satisfying the following conditional expressions:

• 50.00<νdP1<65.00,
• 0.545<θgFP1≤0.5583, and
• −0.010<θgFP1−(0.6418−0.00168×νdP1)
• where
• νdP1:
• an Abbe number of the positive lens with reference to d-line, and
• θgFP1:
• a partial dispersion ratio of the positive lens, defined by the following expression when a refractive index of the positive lens for g-line is ngP1, a refractive index of the positive lens for F-line is nFP1, and a refractive index of the positive lens for C-line is nCP1:
• θgFP1=(ngP1−nFP1)/(nFP1−nCP1).

A zoom optical system comprising a plurality of lens groups, wherein

• upon zooming, a distance between the lens groups adjacent to each other changes, and
• a first lens group that is disposed closest to an object among the lens groups and has a positive refractive power, the first lens group including a cemented lens including a positive lens, the positive lens being one of two lenses cemented to each other to form the cemented lens, the positive lens satisfying the following conditional expressions:
• 50.00<νdP3<65.00,
• 0.545<θgFP3≤0.5583, and
• −0.010<θgFP3−(0.6418−0.00168×νdP3)
• where
• νdP3:
• an Abbe number of the positive lens with reference to d-line, and
• θgFP3:
• a partial dispersion ratio of the positive lens, defined by the following expression when a refractive index of the positive lens for g-line is ngP3, a refractive index of the positive lens for F-line is nFP3, and a refractive index of the positive lens for C-line is nCP3:
• θgFP3=(ngP3−nFP3)/(nFP3−nCP3).

A method for manufacturing a zoom optical system comprising a plurality of lens groups, the method comprises a step of arranging the lens groups in a lens barrel so that

• upon zooming, a distance between the lens groups adjacent to each other changes, and
• a first lens group that is disposed closest to an object among the lens groups and has a positive refractive power, the first lens group includes a cemented lens including a positive lens, the positive lens being one of two lenses cemented to each other to form the cemented lens, the positive lens satisfying the following conditional expressions:
• 50.00<νdP3<65.00,
• 0.545<θgFP3≤0.5583, and
• −0.010<θgFP3−(0.6418−0.00168×νdP3)
• where
• νdP3:
• an Abbe number of the positive lens with reference to d-line, and
• θgFP3:
• a partial dispersion ratio of the positive lens, defined by the following expression when a refractive index of the positive lens for g-line is ngP3, a refractive index of the positive lens for F-line is nFP3, and a refractive index of the positive lens for C-line is nCP3:
• θgFP3=(ngP3−nFP3)/(nFP3−nCP3).