A system for acquiring an image of veins of a finger includes a camera designed to acquire an image of said finger when it is passed in front of it, a lighting device designed to illuminate said finger and a control unit for controlling the illumination intensity of said lighting device. Also, at least one system measures the transmission power of said finger upstream of the camera with respect to the passage of said finger towards said camera, said control unit being designed to control the illumination intensity of said lighting device according to the transmission power measured by said measuring system. Additionally, a method for acquiring images of veins of a finger is provided.