IMAGE FORMING OPTICAL SYSTEM AND IMAGING APPARATUS HAVING THE SAME

• Main Author: KON TOYONORI
• Format: Patent
• Language: English
• Published: 24.11.2011
• Subjects: OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICS; PHYSICS

PROBLEM TO BE SOLVED: To provide an imaging apparatus provided with a compact image forming optical system which allows reduction in its size, simplification of its structure and inner-focusing of a focus lens group, and excellently maintains optical performance throughout an infinity to a very short distance of image forming, despite the image forming system is constituted by four groups having negative, positive, negative and positive power.SOLUTION: An image forming optical system includes a first negative lens group, a second positive lens group including an aperture stop, a third negative lens group and a fourth positive lens group in this order from an object side. The first lens group includes a negative subgroup and a positive sub group in this order from the object side. The third lens group is a focus group constituted by only a cemented lens which includes a negative lens and a positive meniscus lens in this order from the object side and has a convex surface facing the object side.