I am intermediate student on photography. I am intending to buy a full format Canon camera and I am between Canon 5D mark III and mark II. I would like to be able using ISO numbers of 800 or 1600 or even more with less noise. I chose full frame, because I am pursuing better image quality of what my current Canon 550D offers. For this reason bigger sensor would be excellent. Finally I chose Canon as a brand, as it is financial wise to go on using Canon cameras, and because I got used to Canon.
I have made a research on the internet about some specifications I would like my camera to have:
High ISO performance: Canon 5D mark III is better at high ISO numbers. Why is that though, since its pixel size is slightly smaller than the pixel size of the mark II? Have the manufacturers made some other improvements on that?
AF-points: Canon 5D mark III has 61, whereas mark II only 9. I only want this for tracking objects or when I do not want to focus and recompose.
HDR: Mark III has this option I would like to try.
Pixel size: As I mentioned, mark 2 has slightly bigger pixels, but there is very little difference between the two cameras.
Do you know any other specifications of the two cameras, that can somehow help me decide eventually?
What do you think about either cameras? What would you choose if you want to go more professionally, gaining more image quality over your images?