ABSTRACT
With the advent of digital photography, the definition of a standard lens has changed, and now depends on the type of SLR you have. Indeed, it has never been a single focal length, because it varies by film or sensor size. On 8 10-inch film cameras, for example, the standard lens is 300 mm. Again, that conversion factor issue raises its head. To get a lens with a “ standard ” or “ normal ” view, you take the diagonal measure of the sensor. For the Sony A300/ A350, that’s roughly 28 mm, so a 28-35 mm lens would equate to the definition of a standard lens. To exactly match a 50 mm on a 35 mm camera on your camera, you need a 33.3 mm lens. Though the 50 mm is generally accepted as the true standard for 35 mm cameras, by definition the standard lens should be a 43 mm lens, because the diagonal measure of a 35 mm frame is 43.3 mm. The other factor when determining the standard lens for your particular camera is whether the perceived depth is distorted at that focal length. Many 28 and 35 mm lenses designed for 35 mm cameras distort depth regardless of their crop factor, so it’s hard to get a perfect match. Today when one says “ standard lens, ” most of us think of standard zoom lenses. These zoom around the same range that the 18-70 mm kit lens does. Sometimes the overall zoom range is shorter; sometimes it’s longer, like the Sony 16-105 mm, which still revolves around that middle range.
