ISO question.

Hi....I have Canon A620. I shoot mainly in Auto or P mode. Understand from the manual that ISO default is 50 but when shooting in Auto mode it is auto set by the Camera ,correct ?
In P mode is it auto set at all, or always up to me to change it ?
Is ISO 400 digital the same as using a 400 film in the good ol' days ?
Thanks Storm2

If the A620 is like the S2 (probably is in this regard), then you can select the ISO speed in any of these modes: P, Av, Tv, and M. It doesn't self-adjust like in the Auto mode.

The ISO setting represents the (virtual) sensitivity of the sensor, so it that sense yes... it's like 400 ISO film. However, you may find in a small digital camera there is more noise in the image than there was graininess in film. (I call it the virtual sensitivity, because I believe the increased sensitivity is actually electronic amplification, or gain... the sensor itself isn't actually more sensitive in the same way hi-speed film is.)

Thank you very much for your answer .I figured this was it, just wanted to be sure.
Thanks Storm