My colleague Trevor has bought a dSLR and been asking about out of focus blur and how you get it.
I thought I'd explain it in photos. Lie an idiot I did it with the panny which means these are approximations! Doh!!
I hoped these show how larger f stops give less depth of field and more out of focus blur (or bokeh!). f7.1 is smaller than f2.8
So this is approx f7.1
approx f4 you'll notice how less distinct the background is.
This is approx f2.8, unfortunately the sun was so bright I couldn't get the exposure right. But the depth of field is slightly less defined again.
Hope that makes it clear Trev!
I'd have liked to shown larger apertures but I was already at shutter speeds of 1/4000 of a second the pannies limit! I should have used the d300!!