The ornamental design for a camera, as shown and described.
FIG. 1 is a perspective view of a camera showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left side elevational view thereof;
FIG. 5 is a right side elevational view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken lines and the faded areas within the broken lines depict portions of the camera in which the design is embodied that form no part of the claimed design.