Focal-plane shutter for cameras

A focal-plane shutter for digital still cameras, comprising:

• two base plates provided with a blade chamber between the two base plates, each having an aperture for exposure at about a center;
• a plurality of arms pivotally mounted to one of the two base plates;
• and
• a shutter blade group having at least one blade pivotally supported by a plurality of joint shanks with respect to the plurality of arms, placed in the blade chamber so that heads of the joint shanks project toward a photographer side,
• wherein, of the two base plates, a base plate placed on the photographer side has at least one convex portion on an object-side surface thereof, the convex portion being plated with metal,
• wherein the arms come in slide contact with the convex portion and are shifted toward the object side immediately before each of the heads of the joint shanks, which had moved from inside the aperture, has reached a position at an edge of the aperture in an actuation of the shutter blade group,
• wherein a surface hardness of the convex portion metal-plated is substantially the same as a surface hardness of each of the arms, and
• wherein a material of metal plating of the convex portion is palladium and each of the arms is made in such a way that after carbon tool steel is immersed in an alkaline solution to form a black oxide film, chromate treatment is applied to the steel, or titanium is nitride-treated.