I auto focused on city skyscrapers from 7 miles away on a hill. I was expecting the lens to rotate to its maximum. 7 miles seems like infinity to me. But the focus distance as shown in the little window on the lens did not go to the very end; I could twist it a smidgen more after the camera finished focusing. I tried focusing on the clouds, which are surely infinitely away, and still the same thing, just a little closer to the maximum swing. So how far is infinity on the lens if even clouds are not? Also, you'll notice on the Canon 24-70mm lens focus window that the infinity symbol is coupled with an L shaped white marker. What does this mean? When manually focusing in the past, i had always rotated the focus ring all the way to the end, but now i know better. To getter best focus when shooting mountains etc, I need to align the focus ring on the tip of the L mark in the focus window instead of rotating it until it stops. Can someone explain what is going on here?