What is Focal Length?
While a photographic lens comprises multiple lens elements, it can be regarded as a single convex element. The focal length is defined as a distance from the center of such a convex element (principle point) to the focal point (image plane) and it is one of the most decisive factors that determines the characteristics of a lens. * The focal length of a photographic lens is established with the subject positioned at the infinity point. Angle of View (Telephoto & Wide-angle Lens) The area size captured by a photographic lens can be expressed as a diagonal angular field called Angle of View. Generally speaking, a focal length range that provides a similar perspective to the human eye is considered to be somewhere between 40-60mm. With this established as a standard focal length, those with shorter focal lengths are called “wide-angle” and those with longer focal lengths are called “telephoto”. The shorter the focal length becomes, the wider the angle of view (wide-angle), while the longer
