A typical aluminum fan-style flash reflector – the Leitz B-C “Chico” flash gun designed for camera accessory shoes or hot shoes (1954 – 1959).
Toronto. For many years flash bulbs were used to illuminate scenes at night or indoors. Early flash guns were somewhat big and required fresh batteries to reliably trigger a flash bulb via a cable connecting flash gun and shutter sync. The biggest and bulkiest portion of the flash was usually its sturdy, solid metal reflector. Some capable engineer came up with the idea that the reflector could be collapsed like a fan made of aluminum, making the flash gun both more compact and lighter.
To compensate for amateurs and absent-minded professionals trying to use exhausted batteries, so called B-C flash guns came into vogue. This flash gun used a higher voltage battery plus a capacitor to store the charge needed to trigger a bulb. The more exhausted the battery, the longer it took to charge the capacitor, warning the photographer it was time to change batteries. Since the bulb was triggered by the capacitor voltage and current, success no longer relied on battery condition alone.
As flash guns became smaller and lighter, the camera’s accessory shoe could be used to mount the flash gun on top of the camera. Inevitably, the accessory shoe became a hot shoe and was linked to the shutter sync. Flash guns enabled for hot shoes eliminated any need for a cable between flash and camera.
In time electronic flash took over and the single use bulbs became history. As the size of the electronic flash dropped, it soon became a built-in part of the camera eliminating any need for the hot shoe. Low powered flash became a popular means to fill in shadows. On more expensive cameras, a sync socket was included so an external electronic flash gun could be used off camera to soften shadows.
