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 left side elevational view thereof;
FIG. 4 is a right side elevational view thereof;
FIG. 5 is a top plan view thereof; and,
FIG. 6 is a bottom plan view thereof.
Portions in broken lines are for illustrative purpose only and form no part of the claimed design. The dot-dash broken lines define boundaries of, and are not included in the claimed design.