Book excerpt: The 50mm lens is for photography purists. It's cheap to buy, light to carry and gets amazing results. It also makes even the greatest photographers try just that little bit harder to frame the perfect image. As a result, it's the first thing anyone buys after their camera. Life in 50mm shares the greatest photos - and the personal experiences that led to them - from some of today's leading photographers. It also explains why they chose to reject complicated modern zooms and express themselves through the 50mm prime in the first place.