while shooting a HS football game. (sort of a long story)
I was using the 1D4 and 500 f4 lens and I noticed the Ai Servo was not tracking the action. So, I thought to myself "$%$# I'm already having issues with the fairly new camera. So I began the process of elimination; checking my settings etc. and checking lens settings and all was ok or so I thought, but Ai Servo still was tracking the action. So, I kept saying to myself just put the 1D3 on the 500 and be done with it and worry about it later, but I couldn't do it. So, I checked the camera settings again; nothing. Then I checked the lens again and BAM it struck me; the pre-focus switch was set to on. Now, I don't know how it got switched on, especially with the lens coat plastic coverign the switch (you'd have to use a finger nail to move the switch), but it was on and the reason why Ai Servo was not tracking the action. So there was a happy ending.
Well, I guess the moral of the story, which all of you probably already know this from experience, is to always check the settings of your equipment before shooting.
Btw, I shot my 1st game ever in a down poor and cold weather and all I can say is I give much respect to those that do it day in day out. Fortunately, I just took possession of the TT hydrophobia rain sleeve - sweet piece of equipment by the way - which kept my equipment dry. I had to learn the install on the spot, though.
Just thought I'd share this story.