OK, I'm reading the book, taking lots of pictures but wanted a variety of explanations of the above three modes and when one might be more suited over the other two. Mostly I work with the camera sitting on my desk and using the Canon EOS utility to make adjustments to camera settings and snap pics. I get to see instant results and can look at the pics side by side and with the settings showing down the right side of the screen. I'm doing it this way until I understand the controls and what they do.
So far I really like Av mode but don't know why. I guess cos my pics come out better (all of the objects in the field of view are clear, the exposure is good). Of course in Av mode, to get the objects in the field of view to be clear the shutter stays open all day!
The few I've taken in M mode are BLACK almost and you can barely tell there is a picture there so I'm not bothering with it right now.
P mode seems to make everything dark but I can adjust the exposure using the large dial on the back and that's really handy. The thing is, when I do that, the shutter stays open longer and I have to be REALLY still or the pic is blurred. P mode with the flash is great so long as the flash is pointed up. Even outdoors I've noticed that the flash improves the picture quite a bit. That's interesting.
I'm not changing any other setting except the one mentioned in the subject line so before you ask, there's my answer to that. I'm "playing" using the EF 85mm lens, ISO 100 and capturing RAM and JPEG.
So, for the newbie, if you feel like taking time to draw me pictures and explain the three modes listed above, it would be appreciated a great deal.