Thanks Riana. Most of them were taken with my Canon 300D and a Sigma 70-300mm lens. For this shot however I brought out the big guns, my Canon Powershot A540 compact. The scary thing is that it is my favourite shot of the day. Focusing is pretty easy, just lock on to the aircraft and follow them through their manoeuvres and wait until you can snap the shot you want. I have to admit, it takes a bit of practice.
Very nice. I should have gone
Next time 
Wow- I am so impressed with all your aviation photos. I was there at the airshow too and its really difficult. The composition is really good.
What lens did you use and how did you focus so quickly?
Thanks Riana. Most of them were taken with my Canon 300D and a Sigma 70-300mm lens. For this shot however I brought out the big guns, my Canon Powershot A540 compact. The scary thing is that it is my favourite shot of the day. Focusing is pretty easy, just lock on to the aircraft and follow them through their manoeuvres and wait until you can snap the shot you want. I have to admit, it takes a bit of practice.