How to get that bokeh
I found this on my hard disk while looking for a bit of space. Wish I could remember where I got it, but its an easy to follow graphic demonstrating the 3 important aspects of D.O.F (Depth of field)
1: The larger your aperture (lower the number) the shallower the D.O.F. The smaller you aperture (the higher the number) the greater the D.O.F
2: The longer the lens (in mm e.g. 300mm) the shallower the D.O.F. The wider the lens (in mm e.g. 10mm) the greater the D.O.F, when used at the same aperture.
3: The further the subject is away from the camera the shallower the D.O.F, even at the same aperture.