I've recently upgraded to a 60D (from a 300D) and have just tried my Sigma EF-500 DG ST flash. This used to work fine on the 300D but on the 60D when using it in TTL mode the flash defaults to the setting for 105MM, when focusing to take the picture the flash moves through the range down to 28mm and then back up to 105mm which it then sticks on. Trying to take another picture the flash then does the same again. I've got the EFS17-85mm lens fitted to the body.
Any ideas as to what the problem might be? At the moment all the test pictures I've taken are blown out because the flash is too strong. I can revert back to Mh or Ml modes or bounce the flash off a wall or ceiling but I'm confused as to why the flash isn't working when using in the typical configuration like it used to. Does the communication protocol between body and flash change depending upon the model of camera; is my 60D unable to drive the flash?
Given that it's Xmas eve, bit late to ask for another present!