Spot photometers measure the luminance that is emitted or reflected from a small surface area in a physical environment. Because the measurement is limited to a “spot,” capturing dense luminance readings for an entire environment is impractical. In this paper, we provide preliminary results demonstrating the potential of using an off-the-shelf commercial camera to operate as a 360° luminance meter. Our method uses the Ricoh Theta Z1 camera, which provides a full 360° omnidirectional field of view and an API to access the camera’s minimally processed RAW images. Working from the RAW images, we describe a calibration method to map the RAW images under different exposures and ISO settings to luminance values. By combining the calibrated sensor with multi-exposure high-dynamic-range imaging, we provide a cost-effective mechanism to capture dense luminance maps of environments. Our results show that our luminance meter performs well when validated against a significantly more expensive spot photometer.