Editing Normal lens (section)

== What is 'normal'? ==
A test of what is a normal lens then, is to find one that renders a printed (or otherwise displayed) photograph of a scene that when held at 'normal' viewing distance (usually arm's length) in front of the original scene and viewed with one eye, matches the real-world and the rendered perspective, though [[Maurice Henri Léonard Pirenne|Maurice Pirenne]] (in 1970) and others demonstrate that it is possible to see a scene made with any lens in normal perspective if one adjusts the viewing distance; but that range becomes impractically close for wide angle photographs or too lengthy for a telephoto, and it requires viewing it from a static point at the centre of perspective from which the image was made,<ref>Pirenne, Maurice Henri Leonard (1970). ''Optics, painting & photography''. University Press, Cambridge [England]</ref> supporting the observations of perspective paintings made by [[Leonardo da Vinci]].<ref>Da Vinci L. (1970) In Richter J. P. (Ed.) ''The literary works of Leonardo da Vinci'', London:Phaidon</ref>