Abstract: In a flashlight emission system, apparatus for lighting a flash tube to illuminate an object and for controlling the quantity of emitted light from the flash tube, the apparatus being cooperative with a camera having structure for presetting ASA speed of film and aperture value of a taking lens prior to taking, there is provided a device for displaying the limit of object distance for providing an optimum exposure to the film comprising; apparatus for receiving information of the ASA speed and aperture value from the camera to make up first data corresponding to the received information; apparatus for making second data indicative of the limit of the quantity of emitted light controllable by the control apparatus; a device for calculating the limit of object distance from the first and second data and generating an output corresponding to the limit found out by the calculation; and apparatus for making a visual display of the limit of object distance in response to the output of the calculation device.