The invention relates to a light fixture for producing an oblong luminous surface with a horizontal illuminant and a box reflector which has a curved reflector surface and planar reflector surfaces to the side enclosing the curved reflector surface, the horizontal illuminant being disposed at right angles to the planar reflector surfaces to the side, which is characterized in that the curved reflector surface is designed to produce the oblong luminous surface at right angles to the horizontal illuminant, and the planar reflector surfaces to the side are designed to sharply define the longitudinal sides of the oblong luminous surface.