T4i flash shoe interface

In general, how standard is the flash shoe interface?

e.g. would a Nikon flash work? A particular nikon flash has auto zoom. Is that a standard interface that would work with a Canon T4i ?

So, what are good flash unit alternatives to Canon. I do not need a flash unit except for the rare occasion. I prefer to use a transmitter and trigger a power pack with lots of joules. Also trigger using a twinkle flash to a sensor on the power pack.

New to Canon.
Suggestions please.

Why the T4I?
I am new to Canon (shhh been a Nikon camera guy for years, but mostly 4x5 photography). Had a portrait studio setup for a long time.

The T4i offers me something I really need. Direct connect to a laptop for live viewfinder viewing and control of the camera. I need a setup that I can position and walk away from the camera and take shots remotely.

I played with a T3 for a day connected to my laptop and really like what it did. The T4i offers higher res and faster multi-shot rates. And a few more features that I need to explore.

Lorin

The physical characteristics are standard, thus a Nikon, Vivitar or 30 year old Sunpak flash will physically mount. However, as far as electronics all bets are off and I doubt it is documented what will or will not work when mounting a Nikon flash on a Canon body. The modern generic flashes will often work, like a modern Sunpak, because they are designed to recognize the camera body and then run an appropriate algorithm in the computer chip. That 30-year old Sunpak 411, likely will fry the camera electronics because of excessive voltage.

Experiment a bit a see what will happen.

I have used 30 year old flashes on my T1i, in manual and auto modes,with great success. Debate here on POTN has convinced me that if I keep it up, my camera will be damaged. I can always set one of my Canon flashes to manual if I want to play with manual. It does raise the question, "Can I use my modern Canon flashes on my old Yashica manual cameras?" I can attest that they do work, in manual mode, quite well. I don't know whether or not this will hurt the camera (I doubt it) or the flash. I don't want to ruin my Canon flashes so I just use old manual flashes on old manual cameras and new Canon flashes on my DSLRs. I hope this helps.

A new flash on an old "mechanical" body will either work or it won't. Newer flashes have lower trigger voltages which are handled well by mechanical switch closure. The issue is with the older flashes, some of which have quite large trigger voltages at the shoe. A Starblitz 3000BT Twin Flash for instance has 45 volts at the shoe. The solid state switching in the newer camera bodies sometimes just can't take the voltages. Canon for instance suggests a maximum of 6 volts at the shoe.

At the hot shoe, an internal camera circuit shorts center contact and shoe mount, thus firing the flash. Old flashes tended to have high voltages because the closure was accomploished by a mechanical switch. Newer cameras, most DSLR's, use electronic circuitry to cause the closure and these circuits can't handle the high voltages. The site http://dpanswers.com/r​oztr/volt_finder.php shows older flashes and the shoe voltages.

There are ways to use older flash units off camera, using a remote trigger device that can handle the voltage. But the referenced charts shows my Sunpack 411 has 190 volts - you can bet I won't even test to see if it works!