I do a lot of panning shots of bikes and cars. After a while this is boring and try to use as low a shutterspeed as possible. Without VR/OS/IS or whatever I found going to 1/20 impossible and stick normally to 1/60 second. This picture is taken at 1/60. with 24-70 f2.8 lens. the bike was going at 40 mph. I often notice that the focal point is sharp and the rest of the picture has movement in. What is this effect called? How does it occur? Is there a way of setting the size of the sharp area, if so it would be rather dramatic. Any body any ideas?

No one answered these questions, and I can't either. Love the image though. Brings back memories of my late teenage years when my (male) friends had Triumphs, Nortons, BMWs, BSA's and one Harley Liberator, all second or third hand of course. Those were the days: no helmets, long blond hair streaming behind me. Traffic was a lot lighter too; no one ever had an accident.