I never really thought about it before – but the bit where a flash attaches to the top of a camera? They call that the Hot Shoe. It’s one of those things that you just sort of accept. Like apertures and diopters and f-stops – they’re just words and you learn the words and that’s that.
But in fact there’s a reason that they call it a “hot shoe” – as opposed to just “shoe”, for example.
I discovered this while playing with an external flash. The bottom (“foot”) of the flash has little metal contacts that connect to the contacts on the camera’s hot shoe. When you push the shutter release, a connection is made internally that tells the flash to fire. So far, so good.
What makes it “hot” is that on some / many flashes, the entire electrical charge goes through there! Honestly, I never would have guessed that. I just figured there’d be a small, low-voltage signal that triggered the flash to fire. Nope! When the flash is charged, there could be 250 volts or more, waiting around the big pin in the foot of the flash.
Remember when I said I was playing with a flash? The flash had been charged up but then I opened it and took the batteries out. And at one point, the way I was holding it, my hand happened to be touching the “foot” when a finger brushed against one of the battery contacts (the ground contact of course).
It bit me! Before that moment, I simply never would have imagined that a flash would run the full charge down and out the foot, into the camera, then back up into the flash.
That’s why they call it a “hot shoe”!