OPTICAL SYSTEM FOR OBSERVATION AND IMAGING DEVICE PROVIDED WITH SAME

摘要: Provided are: an optical system for observation that has a small optically effective diameter on the object side and makes it possible to increase resolution; imaging device provided with observation. The enlarges subject image forms image. arranged therein, in order from side, at least first lens group positive refractive power is fixed respect formation surface during focusing second moves along axis focusing. distant toward close object, satisfies predetermined conditional expression.