It is said the visual range we can see things clearly is around 50 degrees (diagonal). The standard lens is based on an angle close to 47 degrees (diagonal), and thus comes close to our clear vision range. One of the characteristics of a "standard lens" is its fast speed (f 1.2 to f 2.0). The advantage to these faster lenses is the ability to focus and see through the camera in poor light. Since the 50mm lens introduces very little distortion compared to our vision, it is ideal for accurate and subtle compositions.