A lighting fixture comprising: • a frame; • a lens assembly; • a light source housing with an opening covered by the lens assembly and providing a mixing chamber; • a solid-state light source mounted within the mixing chamber; • an ambient light sensor (S A) mounted outside of the mixing chamber and coupled to the frame, wherein a sensor distribution beam that defines a sensor coverage area on a task surface is provided by the ambient light sensor via a waveguide and is directed in a first direction and a light distribution beam that defines a light coverage area on the task surface is provided by the solid-state light source via the lens assembly and is directed in the first direction such that the sensor coverage area is completely within the light coverage area; and • a driver module coupled to the ambient light sensor and adapted to: • drive (200, 204) the solid-state light source; • read a first output from the ambient light sensor (S A) with the solid-state light source driven at a first output level; • read a second output from the ambient light sensor with the solid-state light source driven at a second output level; and • determine a setpoint based on a difference between the first output and the second output relative to a difference between the first output level and the second output level; • periodically adjust the setpoint to effectively change a light level of the lighting fixture; and • monitor an output of the ambient light sensor and drive the solid-state light source such that the output of the ambient light sensor corresponds to the setpoint. • a frame; • a lens assembly; • a light source housing with an opening covered by the lens assembly and providing a mixing chamber; • a solid-state light source mounted within the mixing chamber; • an ambient light sensor (S A) mounted outside of the mixing chamber and coupled to the frame, wherein a sensor distribution beam that defines a sensor coverage area on a task surface is provided by the ambient light sensor via a waveguide and is directed in a first direction and a light distribution beam that defines a light coverage area on the task surface is provided by the solid-state light source via the lens assembly and is directed in the first direction such that the sensor coverage area is completely within the light coverage area; and • a driver module coupled to the ambient light sensor and adapted to: • drive (200, 204) the solid-state light source; • read a first output from the ambient light sensor (S A) with the solid-state light source driven at a first output level; • read a second output from the ambient light sensor with the solid-state light source driven at a second output level; and • determine a setpoint based on a difference between the first output and the second output relative to a difference between the first output level and the second output level; • periodically adjust the setpoint to effectively change a light level of the lighting fixture; and • monitor an output of the ambient light sensor and drive the solid-state light source such that the output of the ambient light sensor corresponds to the setpoint. • drive (200, 204) the solid-state light source; • read a first output from the ambient light sensor (S A) with the solid-state light source driven at a first output level; • read a second output from the ambient light sensor with the solid-state light source driven at a second output level; and • determine a setpoint based on a difference between the first output and the second output relative to a difference between the first output level and the second output level; • periodically adjust the setpoint to effectively change a light level of the lighting fixture; and • monitor an output of the ambient light sensor and drive the solid-state light source such that the output of the ambient light sensor corresponds to the setpoint.