stupid question alert: what makes a flash fire?

[Davi]

quite literally - what output does the camera send through the hotshoe? is it current or just a short?

[theaxe]

AFAIK it just closes the circuit.

[MartinP]

Just a short circuit is needed.

[ian in lancs]

MartinP said:

Just a short circuit is needed.

yep

[Davi]

lovely job, cheers

[K12beano]

Thought someone's camera had spontaneously combusted when I saw the thread title.......

[Simpo Two]

I thought there was a 'trigger voltage' which varied with the kit.

[Davi]

Simpo Two said:

I thought there was a 'trigger voltage' which varied with the kit.

That was what I was told by someone else, which is partly what prompted the question - I've had conflicting info on it but so far the votes are in favour of a short. I guess the easiest way is to manually short the connections on my flash and see what happens, but it's the only one I've got and I'm quite partial to it!

[MartinP]

It's the voltage the from different flash guns/heads that vary. As modern cameras create the 'short circuit' to trigger the flash electronically, they do have a maximum limit on the voltage that the flash can presents across it's terminals without damaging the camera.

I have heard of certain DSLRs (not Nikon or Canon) being fried when triggering mains powered studio flash heads.

[jcas]

Just a short - http://www.youtube.com/watch?v=R8_dAgaBBdI

[Davi]

thanks for the confirmation guys, nice video too, appropriate as it's what I'm playing with LOL

[Simpo Two]

Davi said:

I guess the easiest way is to manually short the connections on my flash and see what happens, but it's the only one I've got and I'm quite partial to it!

Or just press the 'test' button

MartinP said:

I have heard of certain DSLRs (not Nikon or Canon) being fried when triggering mains powered studio flash heads.

Studio flash is fired by synch lead, IR or RF - don't see how this can damage the camera (but stand to be corrected)

[MartinP]

Simpo Two said:

Studio flash is fired by synch lead, IR or RF - don't see how this can damage the camera (but stand to be corrected)

The issue is with the synch lead, in particular when using hotshoe to PC adaptors on certain cameras. As I said, not a problem with Canon or Nikon but certain cameras don't allow for that type of use and only allow for the 5V or so that modern flash guns generally use. When I did my college course they wouldn't allow non Nikon/Canon owners to use the hotshoe adaptors with studio flash...