Flashgun question

[SamHH]

I bought a second-hand Sigma EF-430 Super flashgun to use with a Canon 300D camera but it doesn't fire, except when using the test button. Am I doing something wrong or is this flashgun not compatible with the camera?

[Goldeeno]

Ive just done a litle reaserch and i dont think its compatible. Has it got a manual setting mode?

[SamHH]

Yes, but it's not firing at all. I also have an old Cobra flash that's not compatible with the camera's metering system but at least fires.

[Gingerbread Man]

Get a paper clip (or something metallic) and try connecting the connections at the bottom together, two at a time. When the right two are connected, the flash should fire. This should help to see if the flash is indeed broken, or, your camera is just not pressing it's buttons.

[SamHH]

Sorry, I wasn't entirely clear. It does fire upon pressing the test button, but not when you connect it to the camera and press the shutter release button.

[DIW35]

You need to be careful when using flashes that aren't designed for use on modern Canons, as you can fry the flash circuits in the camera. Most makes of camera are happy with up to 12v across the flash contacts, but Canon only like a maximum of 5v.

I had to stop using one of my studio flashes plugged directly in to the camera when I realised it had 12v across it's contacts. I now only use that particular flash on a slave unit.

To measure the voltage of the Sigma, put a voltmeter across the central point on the bottom, and the small sprung piece of metal in the groove of the flash mount, where it slides on to the rail of the hotshoe. If it reads more than 5v I would think twice before using it again.