Hot Shoe Definition:
The Hot Shoe is a bracket build into the body of a camera. It is designed to support an external speedlite and has a number of electrical connections that deal with communication to this speedlite.
The word Hot in the name here implies those electrical connection.
Cold Shoe Definition:
A Cold Shoe is a similar to the Hot Shoe but with no electrical connections, hence it’s Cold.
A brief history of the Hot Shoe and Cold Shoe:
Up until the 1960’s cameras didn’t have a Hot Shoe – they had what was called an Accessory Shoe and it was designed to support camera accessories, including flash units. There were no electrical connections on the accessory shoe; These were connected electrically to the camera via an external cable.
From the 1970’s onward, camera manufacturers began to incorporate an electrical trigger contact within the shoe. This changed the accessory shoe into a Hot Shoe. The older accessory shoes were, in effect, Cold Shoes – to signify they had no electrical connections.
Camera manufacturers then began to add other contacts to their hot shoes to provide all more sophisticated communication between the camera and the speedlite. Mostly they kept the same main trigger connection and simply added their own proprietary connections. Except for Sony – they adopted the Minolta standard (check this) which was incompatible with everyone else.
But the hot shoes still maintained legacy connections. Older speedlites could still be triggered from modern cameras. Even modern speedlites could operate from older cameras as well as modern cameras if they were used in manual mode. The trigger signal comes from the same central connection.
(Warning: I have to insert a caveat here – it is risky to connect an older flash unit to a modern camera).
The new connections on the hot shoe allow the camera to ‘wake up’ the speedlite by a half-press of the shutter button. They also allow two-way communication between the camera and the speedlite so the flash exposure can be automatically set, but this is the realm of TTL and its derivatives. If you’re working with manual flash (why else would you be reading this website), these extra pins are not used so you can happily ignore them.
What does a Hot Shoe cover do?
A hot shoe cover is mostly a small piece of plastic that will slide into the hot shoe to provide some protection for the hot shoe contacts. I normally have lost my hot shoe cover within days of buying a new camera and a hot shoe cover has never been included when I’ve bought a second-hand camera. If you’re taking reasonable care of your camera, in most cases a cover will not be necessary.
The hot shoe cover can create some flash issues with your camera internal flash operation. It could operate the hidden switch inside the hot shoe, which will disable the internal flash.
What is the hidden switch for in a hot shoe?
There is a tiny hidden switch in the hot shoe. If you connect an external speedlite to the camera, this switch will signal this fact to the camera. When you select a flash function, the camera will disable it’s own internal flash and assume an external flash has been connected. Similarly if you connect anything to a hot shoe – the internal flash will be disabled. This is fine under most situations, because if something is connected to the hot shoe, it would probably prevent toe pop-up flash opening properly. It means if you have connected an external flash or a radio trigger to the hot shoe, the camera will automatically know this. But if you have simply fitted a hot shoe cover, then the internal flash will be disabled and maybe you don’t know why!
If you’re using your camera for recording video and have mounted a microphone or external monitor, etc. this will not be so much of a problem because I presume you won’t be using flash.
What is the locking pin in a hot shoe?
Because of the number of connections in a modern hot shoe, it is essential that the speedlite doesn’t start to make its way out of the hot shoe over time. Speedlites have a locking pin in their base to ensure this doesn’t happen. When the locking nut is turned, the pin extends into the camera’s hot shoe and locks it in place. The speedlite cannot move now.
For years, I would tighten this locking nut down as hard as possible to ensure perfect reliability of the speedlite connection to the camera. This meant the nut was very difficult to loosen, but I misunderstood how it worked and this was wrong! The locking nut does not lock the flash to the camera by friction. The contacts on the base of the speedlite are spring-loaded so they do a fine job of maintaining their contact with the hot shoe by themselves. The purpose of the locking pin is to ensure the pin alignment doesn’t change. The locking nut therefore does not need to be tightened up too much. Other models of flash use a slide locking mechanism that is easier to use and provides the same locking action.
What can I plug into a Hot Shoe
Generally it’s best if you keep the hot shot for it’s original purpose – to connect external speedlites and speedlite-related accessories. Definitely connect a speedlite, but you could also connect a hot shoe extension cable, or a radio trigger that will drive an external set of speedlites. These devices are most in keeping with the original function of the hot shoe.
But you can, of course, fit other adapters too. You can use the hot shoe as a cold shoe and fit a microphone, smartphone mounting plate, or external monitor, etc. If you’re not using the flash function in the camera this will not be a problem.
Using a Cold Shoe adapter?
There are so many gadgets that can be connected to a camera today and they all can be fitted to the hot shoe. My recommendation is, because of the electrical connections, to fit only flash-related accessories to the hot shoe. For other things like external monitors, microphones and amplifiers, smartphones, etc. I would suggest you buy a camera cage and fit everything to this. It takes the physical strain of trying to support the devices away from the camera. It always makes me nervous to see large devices bolted to a hot shoe – the camera looks so vulnerable.
Canon has removed the hot shoe center pin on some cameras
I must add a word of caution here; Canon has removed the center pin in its hot shoe on EOS 250D and EOS3000D models. This makes these cameras unusable for manual flash as manual flashes are triggered by the center pin. Only Canon automatic flash units will operate on these cameras, which means that if you want to experiment with manual flash, you cannot use these cameras.
This is only happening on some Canon cameras, but it’s worth it to check for this center pin when buying Canon.