580EX II goes off randomly itself.

Hi All,

I'm hoping somebody can shed some light on this. I received an 580EX II for Christmas (lucky boy!) and in general it works well. However there is a really weird problem that happens intermittently. It has happened on four separate occasions now. The flash occasionally goes off all by itself. I definitely didn't depress the shutter or pilot light!!!

The first time it happened, I had just taken a shot and was lowering the camera, and suddenly the flash output another flash. The second/third occurrence was then same scenario. On fourth occassion, the flash fired three times while I was adjusting the head!? Again, no fingers anywhere near the pilot/shutter buttons! Just after it had fired 3 times, I tried pressing the pilot light to fire manually, thinking the button might be "stuck down", alas the flash wouldn't fire at all. It was like the capacitor had discharged during the random firing, even though the pilot light was red, indicating full charge.

I'm trying to work out if the problem only occurs when the flash is on the camera (350D). So far I haven't been able to reproduce the problem when the flash is unmounted, but then it has only happened intermittently so it's hard to reproduce at all, let alone on the camera or off camera. It's almost like something is shorting inside the unit causing it to fire randomly, but its so hard to reliably reproduce the issue.

Does this sound dodgy.. I tried googling but there doesn't seem to be many instances of this on the net.

Any thoughts would be greatly appreciated!!

My thoughts on your dilema.

Make sure the flash is inserted all the way onto the camera so the contacts are not getting shorted.

Also, might you have pressed the FEL (*) button on your camera? That will fire the flash, albeit just a pre-flash and not a full burst.

Also, the DOF preview button makes the flash act as a modeling light.

If none of that is an issue you may have a faulty flash.

Thanks Mike they are some very good ideas there that I hadn't considered!

I cannot be certain I didn't press the FEL (*) button, so that is worth me keeping in mind!! The DOF button is a little harder to press accidently so I think if either are the cause, the * button is likely the culprit. I'm confident with the mounting of the unit in the hotshoe, as the flash appears to have a locator pin that goes down into the hot-shoe, so presumably if the flash was not fully inserted, I would be unable to engage the locking mechanism. I'll keep monitoring it over the next few days now that I'm aware of the above (particularly the FEL button). If I keep getting the problem, I might need to get the unit checked.

Many thanks for the ideas!! I'll make an effort to update this post with my findings after a few days of testing.

Please make sure your flash unit is shut off before mounting on the camera body, as I have been told this could cause damage to the camera body circuits on contact with a fully charged flash unit. I am wondering if this has already happened?

Thanks for the tip Birdsmartin but no, I've never mounted the flash in the hotshoe whilst powered up.

However having kept an eye on the situation, I'm now convinced more than ever that Mike solved the issue for me. I'm 99% sure I was inadvertently hitting the FEL button, which appeared to be randomly firing the flash. This replicated the behavior perfectly, and the way I was holding the camera, my thumb was right next to the FEL button. With the extra weight of the flash on the camera, my fat thumb has clearly edged across the button, setting off the flash.

Thanks for the help guys, and a HUGE thanks to Mike for solving the problem... that was some good lateral thinking!!!