Patent ID: 9618728
Date: 2017-04-11
CPC Classifications: G02B

Claim:
1. A macro lens system, consisting of, in this order from an object side: a first lens group having a positive refractive power; a second lens group having a negative refractive power; a third lens group having a positive refractive power; a fourth lens group having a negative refractive power; a fifth lens group having a positive refractive power; and a sixth lens group having a negative refractive power; further comprising: a stop which is fixed during focusing operations provided between the surface of the second lens group toward the image side and the surface of the fourth lens group toward the object side; characterized by: the second lens group, the fourth lens group, and the fifth lens group being independently moved in the direction of the optical axes thereof when focusing from an object at infinity to an object at a most proximate distance; and the second lens group moving toward the image side and the fourth lens group moving toward the object side when focusing from an object at infinity to an object at a most proximate distance, wherein: the fourth lens group has a cemented lens formed by a negative lens and a positive lens, with the positive lens being at the side closest to the object side, and satisfies Conditional Formula (7) below: wherein ν4dp denotes the Abbe's number of the positive lens that forms the cemented lens of the fourth lens group with respect to the d line, and ν4dn denotes the Abbe's number of the negative lens that forms the cemented lens of the fourth lens group with respect to the d line.