Can I use an older pre-digital flash unit on my 300D?

DwainDibley

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I saw a couple of older flash units in a charity shop yesterday, nearly bought one to go with my Canon 300D but then a bloke standing next to me who sounded like he was experienced in photography said that those flash units probably wouldn't work on my camera, or would damage/burn out the flash circuitry on either the flash unit or my camera.

Is this true, or can I use an older flash on my dSLR without any problems? I'm just after a cheapie at the moment until I can afford a proper, better dedicated flash.
 
Without knowing the flash I will say this some older model flashes had a high trigger voltage which indeed could burn out a canon camera's electronics. If I put that much money in a camera I would be leery of sticking a flash on it without knowing the trigger voltage. A volt ohms meter will tell you that.

That said the trigger voltage of most flashes is low enough to use. The only one I personally know of that did it was the early vivtars made in korea. But again If I put that much money in a camera and there was any chance, I would skip the bargain model.

If you have a real camera store in the town you might pick up a cheap flash and have them test the trigger voltage for you. Again it is a big risk to save a few bucks and burn up your camera.
 
Any idea on what the trigger voltage would be for my camera? I have a voltmeter, and just thought - I have an old film SLR camera, which has a Morris 300TX-D flash unit in it, though I'm not going to try it on my camera just yet in case I burn out any electronics!
 
Thanks, useful link! Though no Morris on there. Just measured the voltage at 4.6 volts on it though (but was very tricky - couldn't get a reading from it when the flash actually discharged, might try again though!)

EDIT: Just tried again, flash voltage reads 4.6v when charged, drops to zero when flash fired, then builds back up to 4.6 as the flash rechrges and becomes ready again.

Think I'll be safe rather than sorry though, and stick to the built-in one till I can buy a flash which I know won't blow the 300D's circuitry.

I have a Jessops (big UK photography chain) store locally, might take a trip up there when I'm feeling a bit more flush financially :)
 
They can probably give you a definte reading on the trigger voltage of what you have as well. There is something else you can do to use yours. Its a bit of a pain though. use a slave sensor to fire the big one and your small on camera to trigger it if you need more light than the on camera will do.

I fire my studio lights that way. I have a tiny trigger lash with guide number of about twenty that I use to trigger a slave backlight which creates enough light to trigger the big flash. Just a thought.

And four sounds about right or a trigger voltage. My 283 is about that.
 

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