580EX II starts in E-TTL but switches to TTL

<p>Hello! I have a Canon 40D and have previously been using the 430EXII in E-TTL with no issue. I recently upgraded to the 580EXII and on my first shoot, the flash started out in E-TTL and was working perfectly, but about 50 exposures into the shoot, the flash switched to TTL and fired a full power flash every time after that. I tried turning the flash and camera off; turning the camera on first and then the flash, sometimes that worked, and sometimes it didn't. I have played with the flash a lot since the shoot and cannot replicate the issue, but it makes me pretty nervous that it happened at all. I found this gallery http://www.causticminds.com/Site/hotshoefix/11385808_SmMoG#800125460_PmU6j showing how to tighten your hot shoe screws, but this must not be a 40D because I wasn't able to pry the clip out with a screw driver. Does anyone have any experience tightening the hot shoe screws on a 40D? What should I use to try cleaning the hot shoe contacts? I have several weddings coming up and I want to make sure that this problem doesn't rear it's head at any of them. Any tips?</p>

<p>I'd bet it was just a bad connection between the flash and body. Most of the time jiggling the flash probably would solve the problem. Take it off and put it back on if that doesn't work. IMO the 580EXII has a screwy foot. The weatherproofing gasket-gizmo is already wearing out or out of alignment on mine. If I don't pay attention it can occasionally seat poorly even with the foot lock on.</p>

<p>Just took a peek at that caustic minds tutorial, and then had a look at my 40D. They are exactly the same, and I assure you that the cover/clip comes out the same way. But here's another tutorial, using a different procedure to remove the clip on an older Canon that, while black, is still the same as the 40D. http://www.conraderb.com/flashrepair/ </p>

<p>Canon hasn't changed this design in a long time. But this would only fix a loose hotshoe, and you may have a different issue. If you can wiggle the hotshoe, do this, if not, look for another solution.</p>

<p>If the shoe isn't loose I'd guess that the contacts on the camera shoe and the foot on the flash should be cleaned. Sometimes new gear comes with something on electrical contacts that prevents good electrical contact.</p>

<p>It is as Matt describes--the redesigned rubber gasket of the 580EX II sometimes causes the flash to lose contact with the hotshoe of the camera. When this happens, the flash goes into TTL, not ETTL, and fires full blast. It it isn't due to the gasket, and wiggling the flash doesn't re-establish contact, the other possibility is your camera's hotshoe plate is loose, as you discovered.</p>

<p>Use the link Jim provided for further information about the camera's hotshoe plate. If you are successful and can tighten the screws under the plate, and still have the problem, it is the fit between the flash and hotshoe.</p>

<p>I bought an eraser stick and use that to clean the contacts. Make sure you don't get the eraser crumbs in the camera, though.</p>