Looking for subjects? Chances are, hundreds are blooming outside your door. Never shot flowers? You can learn the basics pretty quickly by photographing tulips. They are popping up in parks and gardens everywhere. And for the ultimate in tulip-shooting, make your way to Ottawa, where each spring more than 3 million flowers bring a rainbow effect to gardens during the Canadian Tulip Festival. With more than 125,000 visitors, organizers say it's the largest event of its type in the world.