Underexposed 10d with speedlite

[onpiopah]

I have a 10D with a 550Ex speedlite.
When I shoot in fully automatic mode at a dark image, the result is underexposed.
I assumed that the camera and flash would automatically expose the picture correctly.
I assumed this because of the cost of the flash.
Am I wrong or is something broke, lighter images are not underexposed.
Any advice would be welcome

[Steve Lutz]

Could you post an example? My 10D with 550EX almost never underexposes. If anything it overexposes. I usually drop the flash power 2/3 of a stop to avoid the bright "blasted by flash" look. Generally, even a 220EX is more than enough flash for my 10D or Digital Rebel. Here's one shot at -2/3 stop on the 220EX flash, at ISO 200, Av mode 1/200 @ f/8. Good exposure on the dancers.

[Peter_AUS]

But Steve, they are shooting in Auto Mode, which makes a big difference doesn't it.

Your example is in Av mode where you set up a choice and the camera takes care of the rest.

What is wrong with the girl black top, blue jeans, there is a redness/bump just right of here belly button, very distracting.

[Steve Lutz]

But Steve, they are shooting in Auto Mode, which makes a big difference doesn't it.

Your example is in Av mode where you set up a choice and the camera takes care of the rest.

What is wrong with the girl black top, blue jeans, there is a redness/bump just right of here belly button, very distracting.

True enough. Auto mode is a different animal. I never use it though, prefering either program mode with -2/3 stop flash exposure compensation (I have the software hack on my Rebel, so I have FEC enabled on my Rebel!). Or, as in this shot, because I wanted to freeze the action, I used 1/200 of a sec @ f/8 at ISO 200. The camera was a rebel, the flash a 220EX and the lens was the 18-55 kit lens.

The redness/blotch is either a tattoo or a birthmark. Whatever it is, it isn't the camera's fault. The mark is on her skin. Here you can see it a bit more clearly. Looks like a tattoo of a salamander.