Imagine this ... You are on a lovely grassy knoll on Richardson Bay facing San Francisco with the Bay Bridge and Belevdere on the left and Sausalito on the right. You are shooting 6x17 with a 210 Sironar-S. It's wide. The actual image cropped would be more like a 6x24 or 6x30. You have a roll of Fuji 160S loaded on frame 3. The composition is weakest in interest to the middle left of SF where the bay bridge and Alcatraz are in the very distant background. Timing, Timing, Timing. A pair of speedboats enters frame right and they are heading right through the foreground. You have the shutter cocked and the cable release in your hand. The dark slide is out. Here they come wait for it, wait for it. There in front of S.F. got it! Wrong!!! As they continue their trajectory you realize that if you shot them to the left in the weakest area of the composition the image would have been far more interesting in terms of placement since they were also leaving a pair of wakes in the water across the frame!!!! You only get one shot in the time it takes for them to get from one side to other. Of course there will be no more boats the rest of the session. It's a hard way to learn how to see.