Given the lack of a clear correlation between human vision and camera lenses, explanations in photography texts to account for this rule's efficacy tend to gloss over or merely restate the phenomenon, claiming that using 50mm lenses "approximates the angle of view and magnification of human vision", or that "the normal focal length for a given format most closely approximates human sight, and projects an image with the least distortion and compression of space from foreground to background", or that "the perspective is correct and we are most comfortable with a picture captured with a 50-mm lens".