The Tempophot Light Exposure Meter is a handheld photovoltaic selenium cell light exposure meter manufactured by the German engineering company Metrawatt AG in Nuremberg, Germany. Originally introduced around 1935, it features a mechanical calculator dial, a built-in swivel baffle / resistor shunt for varying light conditions, and a needle indicator to determine correct film exposure. Key Features: Maker: Produced by Metrawatt AG (which later merged into Gossen-Metrawatt ). Casing Material : Features a distinct, heavy-moulded Bakelite housing. Sensory Technology : Uses a built-in selenium photocell. This cell generates its own low-voltage electrical current when exposed to light, meaning the meter does not require batteries to function. Baffle / Shunt Control: A side button adjusts the meter cell mechanism, allowing the needle to point to specific indicator numbers on an internal scale. Calculator Dial: ...