Optical system and imaging apparatus including the same

Abstract

In an optical system in which a focal length of an entire system is shorter than a back focus, an image stabilizing lens unit, is at a position adjacent to an aperture on an image side and a cemented lens obtained by cementing a positive lens and a negative lens is on an object side of the aperture diaphragm, and the focal length of the entire system, a focal length of the image stabilizing lens unit, a focal length of the cemented lens, a distance on the optical axis from the aperture to a lens surface on the object side of the image stabilizing lens unit, and a distance on the optical axis from a first lens surface on a side closest to an object to a final lens surface on a side closest to an image when an infinite-distance object is brought into focus are set.

What is claimed is: 
     
         1 . An optical system of which a focal length of an entire system is shorter than a back focus, wherein, when an image stabilizing lens unit, which moves in a direction including a component perpendicular to an optical axis to move an imaging position, is arranged at a position adjacent to an aperture diaphragm on an image side, a cemented lens obtained by cementing a positive lens and a negative lens is arranged on an object side of the aperture diaphragm, the focal length of the entire system is set to f, a focal length of the image stabilizing lens unit is set to fis, a focal length of the cemented lens is set to fc, a distance on the optical axis from the aperture diaphragm to a lens surface on the object side of the image stabilizing lens unit is set to Dis, and a distance on the optical axis from a first lens surface on a side closest to an object to a final lens surface on a side closest to an image when an infinite-distance object is brought into focus is set to DL, condition equations
   0.00 <Dis/DL< 0.25,     0.3 <fis/f< 3.5, and     0.3 <−fc/fis< 3.5   
       are satisfied. 
     
     
         2 . The optical system according to  claim 1 , wherein, when lateral magnification of the image stabilizing lens unit is set to βis and lateral magnification of a lens unit arranged on the image side of the image stabilizing lens unit is set to βr, a condition equation
   0.1<|(1−β is )β r|< 1.3
 
 
       is satisfied. 
     
     
         3 . The optical system according to  claim 1 , wherein, when the image stabilizing lens unit includes a single lens and an Abbe number of a material of the single lens with respect to a d-line is set to νdis, a condition equation
   35<ν dis  
 
 
       is satisfied. 
     
     
         4 . The optical system according to  claim 1 , comprising: a first lens unit with positive or negative refractive power and a second lens unit with positive refractive power in order from the object side to the image side, wherein the second lens unit moves during focusing, and the cemented lens, the aperture diaphragm, and the image stabilizing lens unit are included in the second lens unit. 
     
     
         5 . The optical system according to  claim 4 , wherein the first lens unit includes a negative lens in a meniscus shape having a convex surface on the object side and a positive lens in order from the object side to the image side, and the second lens unit includes a negative lens in the meniscus shape having a concave surface on the image side, a positive lens, the cemented lens obtained by cementing the positive lens and the negative lens, the aperture diaphragm, the image stabilizing lens unit, which moves in the direction including the component in the direction perpendicular to the optical axis to move the imaging position, a cemented lens obtained by cementing a negative lens and a positive lens, and a positive lens in order from the object side to the image side. 
     
     
         6 . The optical system according to  claim 1 , wherein the lens on the side closest to the image is a positive lens having an aspherical surface. 
     
     
         7 . An imaging apparatus, comprising: the optical system according to  claim 1 .