Some lenses are razor sharp, while other lenses always produce pictures that are a bit blurry—even when the subject is in focus. As a general rule, the more expensive, heavier, and larger the lens, the sharper it will be. To get a more objective comparison of the sharpness between two lenses you’re considering, just search the Internet—the photography community examines the sharpness of all new lenses. Tip: Prime lenses are usually sharper (and lighter, and cheaper) than zoom lenses. However, many professional zoom lenses are as sharp as the best primes. Either way, I prefer the flexibility of zoom lenses. For an example of how lens sharpness can vary, check our reviews of the Sigma 24-105 f/4 and the Tamron, Canon, and Sigma 70-200 lenses. Please don’t obsess about lens sharpness, though. Most lenses are just fine, and your technique is much more important than the lens’ optical quality. Read Chapters 4 and 5 of Stunning Digital Photography to improve the sharpness of your images without buying a more expensive lens.