Flash won't work on a 5D Mark II

Is it me or the camera? I wanted to take some photos of my house so I put my Sigma 12-24mm lens on my 5D Mark II with my 580EX II flash which I had just installed new batteries. The Pilot light quickly lit up and I was able to flash the unit manually by pressing the button. When I put it on the camera it would not flash. The 580 was set to ETTL. It used to work but has been sitting idle for about a year.

Anyone have any suggestions on what may be going on?

Any chance the flash is set to slave? I don't have a 580ex to test with but it should have a slave mode. It should not be set to slave mode. Also, check the camera flash menu to see if it's disabled there.

rmexpress22 said:

Any chance the flash is set to slave? I don't have a 580ex to test with but it should have a slave mode. It should not be set to slave mode. Also, check the camera flash menu to see if it's disabled there.

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Good suggestions. I'd also look at the contact pins on the flash and the hotshoe and check for corrosion or something funky. Finally, does the flash work with a Canon lens? Maybe there is some incompatibility. (Shrug. Just spitballing ideas.)

Also go into the 5D Mark II menus and try changing settings under External Speedlite control. That will at least tell you if the flash is talking to the camera.

If a Canon flash is in slave mode when mounted on a camera, it automatically switches over to normal mode, as soon as you use the camera.

Just to second Scott's advice, look on the third wrench tab in the menu for "External Speedlight control". Then select "Flash function settings".

If the camera can't talk to the flash it will say "incompatible flash or flash turned off"

If it can talk to the flash then the various function options will appear. At the bottom of the page (but out of sight until you tab down) is "Flash firing - enable/disable

Good luck!