N2bnfunn wrote in post #16676650
...but when I attached my flash the auto ISO is not working correctly...
Oh yes it is. Since flash metering in E-TTL is done at the moment just prior to exposure, you can't know which ISO would be appropriate until you're taking the picture, and then it's too late to change it. If the camera did change it at this moment, then your previous setup for the exposure of the ambient light would be void.
Likewise, when using manual flash, you must have a known and consistent ISO value to set your manual flash power against, or you'll be completely lost about which power level to use.
Don't be sad know. A lot of Canon users seem to belive that the auto ISO when using a flash isn't working, so you are in good company. Some even think it's Canon's engineers that are stupid. But it's working the way it should, and the reason that most people think it's not is in this case just that Canon's engineers thought about this a bit furhter.