PURPOSE: To obtain the titled lens which is well corrected of an aberration fluctuation and has a large aperture ratio by allowing an optical system having 4 lens groups which have positive, positive, negative and positive refracting powers successively from an object side to make prescribed motion.
CONSTITUTION: This lens has the four lens groups consisting, successively from the object side, the 1st lens group 1 having the positive refracting power, a stop R7, the 2nd lens group II having the positive refracting power, the 3rd lens group III having the negative refracting power, and the 4th lens group IV having the positive refracting power. The 1st lens group I has at least one negative lens of which the strong concave face is directed to an image plane side. Focusing from an infinite object to a short distance object is executed by integrally extending the front lens group consisting of the 1st lens group I, the aperture Y7 and the 2nd lens group II and extending the 3rd lens group III at the moving quantity smaller than the moving quantity of the front lens group.
MATSUSHITA TAKASHI
JPS5848723A | 1983-03-22 | |||
JPS61238010A | 1986-10-23 | |||
JPS5948723A | 1984-03-21 |