I have a Canon Rebel T2i capable of capturing up to 3.7 frames per second. Even with the walk around lens (the lens that came with the camera body in the kit) I can zoom in like this. I have a favorite photo of one of my dogs. In the original picture he is nothing more than a small, insignificant figure way in the back. The photo was actually of one of my other dogs who was running past. I had it on sports mode and zoomed in to the imported photo and cropped this out using Corel Paintshop Photo Pro X3. Literally a spot that was no more than 10% of the entire photo, and that is being generous. Here is the shot....
https://www.facebook.com/photo.php?fbid=481690122569&set=a.481690057569.265883.828432569&type=3&theater
I need to go back to the raw image and re-edit it now that I have CS5 and Lightroom 3.