No - you're not seeing double.

I managed to capture these almost exactly identical images of two different racers, which is quite impressive (at least to me) when you consider that I was shooting handheld for a good portion of the day. The shots were taken only five seconds apart, but if you look very closely at the background, you'll see the shots are slightly different.

Normally, I would have recommended using a tripod shooting at such a long zoom length (439mm), but my Sigma 150-500mm f/5-6.3 APO DG OS HSM has that lovely little Optical Stabilization feature, so I was able to shoot by hand.

Technical Data: Canon EOS 7D, Sigma 150-500mm f/5-6.3 APO DG OS HSM at 439mm, 1/1020 and 1/790 sec (respectively) at f/6.4. ISO 200. No post production. 2010 Pittsburgh Vintage Grand Prix, Pittsburgh, PA.

I think I'll pass on doing my normal full critique of these two - mostly I'm just liking how cool these two photos turned out. Even though some of the cars are cut off in both photos, I still like the composition of the shots - I think it helps to give the sense of motion like the previous shot. Feel free to post your own critiques in the comments if you like.

Fun stuff.

- Bill