Camera Flash Bulb
There was NO built-in camera flash, in fact there was no electronic flash, period. I use to own a flash gun that used flash bulbs, which I attached to the camera with the flash sync cable plugged into the camera bulb flash socket. The flash bulb was like a light bulb in size which you screwed into the flash guns bulb holder directly in front of the large flash reflector. The bulb was filled with magnesium wire and when you fired the shutter the batteries in the flash gun would ignite the magnesium in the flash bulb and create a flash.
Flash photography is the use of a camera flash bulb in a variety of possible situations where there doesn't seem to be enough light. The most common use of flash photography is group portraits at gatherings where there is not enough light to take a satisfactory exposure. But there are many other situations where the flash could be used such as: fill-flash situations when the background is brighter than the subject, using the flash to light up a room and creating better coloring, or using the flash to freeze a moving object in a dark situation
Camera Flash Bulb