Some nice pics there mate. You really can't go wrong with Canon. I have had mine for a month or so now and still delete more pictures than I keep LOL. Like others have said, wouldn't bother with the fisheye...save your money and get a good 70-300mm with IS if you can afford it
Thats depth of field. What that means is that the camera has been focused on a set point (which you decide). Due to the camera being focused on a specific point it means that the back ground will be blurred.
Apologies for the hijack but this will show what I mean a bit better....
On this shot you can see that area I wanted in focus what the frame under the petrol tank, that means that ONLY that point is in focus and everything else is out of focus...
Same thing on this shot.... I only wanted to focus on the 'S' on the tank, due to the lens I was using having a very shallow DOF it means the 'S' is super sharp and the background is out of focus.
Its very cool when you get it right, and some lenses have a shallower DOF than others. This one is about as shallow as it gets (50mm f1.8 prime lens).
Here's something that I reckon can explain it better than I can!.
ive gotta admit i did alot of editing to that to get it like that, as i totaly balls'd up when i took it, tooked fine on the preview but when i got home it wasnt. i am gonna invest in one of the thm tho
ive had it on "M" since ive got it, only way too learn, im eding up taking bout 20pics of one thing haha, but im learning though luckily a few of my mates who do it for a hobby or extra money so they are helping me out with bits im stuck on