10D & 550EX Problem

Is there a wobble in the hotshoe? This has happened to me quite often. The screws that hold the hotshoe tangs become loose, causing the flash pins to lose full contact with the hotshoe contacts (those little silver circles between the hotshoe tangs). This especially happens when shooting in vertical since the flash is on its side and that bit of play in the hotshoe is enough to pull some pins off the contacts. What you need to do is remove the thin black metal plate that covers those little screws. Look very closely at the hotshoe and you will see that there is a very thin metal plate there. Use a micro flathead screwdriver to lift the plate up (stick the micro flathead underneath the plate at the lip you see surrounding the silver contacts) and slide it off (towards the rear, not forward towards the front of the camera). Take a very close look and you'll see what I mean. Once you get that thin shield off, you'll find four tiny silver screws that are probably loose. Tighten them and replace the shield. (I leave my shield off.)

billash wrote:

I've found that quite often when shooting verticals with this combo
I get underexposed images....often up to two stops under.

Is this a common problem experienced by others, or does this sound
like a malfunction?

I'm using a Canon 28-135 IS lens w/ hood. The problem doesn't seem
to correlate to the zoom focal length I'm using at the time. It
just happens too frequently for me to feel comfortable shooting
verticals for the time being.