Bright intermediate telephoto lens

Abstract

Abstract PURPOSE:To prevent deterioration in the sharpness of the contour of an image by cementing the 1st - the 7th lenses, i.e. a positive, a positive meniscus, a negative and positive cemented, a positive, and a positive lens from an object side and satisfying various specific conditions. CONSTITUTION:The lens system consists of the 1st positive lens having high positive power on the subject side, the 2nd positive meniscus lens having high positive power on the subject side, the 3rd negative meniscus lens having high negative power on the image side, cemented lens consisting of the 4th negative lens having high negative power on the subject side and the 5th positive lens having high positive power on the image side with a diaphragm between, the 6th positive lens, and the 7th positive lens having low power. Inequalities I -XVII are satisfied, where ri and di are the radius of curvature of the (i)th surface and the lens thickness or lens gap of the (i)th lens, ni and nui are the (d)-line refractive index and Abbe number of the (i)th lens, and (f) and f1.i are the focal length of the whole system and the focal length from the 1st surface to the (i)th surface.

Inventors

• 👤 Ryota Ogawa
• 👤 良太 小川

Bibliographic Details