Good flash; but not to each camera

The Speedlite 580EX II is well made and makes a robust impression. It offers fully automatic E-TTL setting also many opportunities for manual adjustment. The flash output is super; enough to illuminate a Festhalle! In short: a great device!
The three star result (unfortunately) from the fact that the device does not work at all Canon D-SLRŽs equally well! For the professional equipment like the EOS 1D, EOS 5D and EOS 30V analog, EOS 3 works the 580 EX II properly. At the small EOS 400D, however, the flash output will always be too weak calculated, so that the pictures always appear a little too dark. Since I got now reported identical experiences of other EOS 400D- owners, which seems to be no exception with my EOS 400D. Here the coordination between camera and flash unit is not true! Presumably the 580EX II is a problem in the flash output calculation of APS-C cameras!