The camera obscura (also camera oscura or camera ottica) had an indisputable impact on the development of town view images. In the 17th century, the device was avidly promoted by the Venecian Francesco Algarotti (1712-1764). According to Count Algarotti, the camera obscura helped painters to choose the best compositional arrangement, allowing them to suitably organize light and shade, thus achieving a convincing gradation of depth. Algarotti also observed that the most accomplished vedutisti used the camera obscura on a daily basis in their work and was „as necessary a tool for painters as the telescope was for astronomers or the microscope for physicists“. Anton Maria Zanetti (1706-1778), another great promoter of the camera obscura, mentioned Canaletto in this connection, who used this optical device as an auxiliary medium for enhancing his imagination.