Abstract: Heat-expandable microspheres containing a thermoplastic resin shell and a thermally-vaporizable blowing agent encapsulated therein. The thermoplastic resin is a polymer of a polymerizable component containing acrylonitrile, methacrylonitrile and acrylate ester and which satisfies specific conditions 1 and 2, where Condition 1: the amount of the acrylonitrile (A)<the amount of the methacrylonitrile (B), and Condition 2: the total amount of the acrylonitrile (A), the methacrylonitrile (B) and the acrylate ester (C) in the polymerizable component ranges from 61 to 100 wt %. Also disclosed are hollow resin particles manufactured by expanding the heat-expandable microspheres, a composition containing a base component and at least one selected from the heat-expandable microspheres and the hollow resin particles, and a formed article manufactured by forming or molding the composition.

Abstract: An objective lens for an endoscope, comprising a first lens group having a negative power, an aperture stop, and a second lens group having a positive power arranged in this order from an object side, wherein the first lens group comprises at least a negative front group lens having a concave surface facing an image side, and a positive front group lens having a convex surface facing the image side arranged in this order from the object side, and the second lens group comprises at least a positive rear group lens having a convex surface facing the image side and a cemented lens formed by cementing together a negative lens and a positive lens being arranged in this order from the object side, and wherein the objective lens for an endoscope is configured to satisfy a predetermined condition.

Abstract: An objective lens for an endoscope, comprising a first lens group having a negative power, an aperture stop, and a second lens group having a positive power arranged in this order from an object side, wherein the first lens group comprises at least a negative front group lens having a concave surface facing an image side, and a positive front group lens having a convex surface facing the image side arranged in this order from the object side, and the second lens group comprises at least a positive rear group lens having a convex surface facing the image side and a cemented lens formed by cementing together a negative lens and a positive lens being arranged in this order from the object side, and wherein the objective lens for an endoscope is configured to satisfy a predetermined condition.