It is worth noting what Cary said about shooting at SXM being difficult. Planes take forever to get to you head on as you're literally in-line with their track... then all of a sudden in 5 seconds the plane is in front of you and then gone behind a fence and touchdown. The bigger the plane, the more this effect is exaggerated! It is extremely stressful but very rewarding if you nail it. It is FAR easier to shoot at Panera or Bayswater where you have a lifetime to lock on the plane and track it slowly for an eternity at a nice constant angular velocity ... The best setup for SXM would be a 50MP 2.7x crop sensor with an 4mm fisheye to 500mm f/8 zoom lens