10 out of 10 points and recommendedSharp, fast focus, weather sealscost , focus - see comment
Mainly shoot youth sports with a Canon Mark II. Always shoot off mono-pod, will occasionally pickup mono-pod and shoot handheld. Why pick the 500mm? Both the 400 f2.8 and 600mm f4 cost and weigh much more than the 500mm. The 500 gives a little more reach than the 400, not quite as far as the 600. For outdoor sports (soccer, baseball, softball) this gives great isolation of the player. If you shoot all day (7am to 5pm) the extra couple of pounds will make a difference by the end of the day. For low light (Friday night football) have a 300mm f2.8, for indoor (volleyball, basketball, hockey) the 300 is more versatile than the 400reviewed November 21st, 2006
In low light, ISO >1250 shutter <250 at F4, can detect slower focusing compared to the 300 f.28 even using just the center focus point. A low battery will also slow focusing down.
Superlatives are needed to describe the picture quality, regularly make sharp detailed 13”x19” prints. Have used the 1.4 extender with good results. Example: Girls softball shooting from the outside the fence (250 ft?) towards home, frames the batter, catcher and umpire.
Horror Story. The weather seals do work. Camera was on, and had slid to the back of a small power boat. Imagine my concern as another boat approached ours and I watched a WAVE come over the side of our boat onto my camera.