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; and,
FIG. 6 is a top plan view thereof.
Portions in broken lines are for illustrative purposes only and form no part of the claimed design. Dot-dash broken lines define the boundaries of, but not included in, the claimed design.