In a camera having means for arbitrarily selecting the exposure condition of a film thereby to generate a signal based on said selection, said signal representing exposure information and having a temperature coefficient, and exposure time determining means for determining the opening time of the shutter of the camera on the basis of said signal, said exposure information being produced for a speed light during the photography using said speed light, there is provided signal transfer means for receiving the signal of said exposure information as input and transmitting said exposure information to said speed light. Said signal transmitting means has a transmission function including a temperature coefficient opposite in polarity to said first mentioned temperature coefficient.