Quadrangular photography is the most suitable to take pictures of brids, views or big natural landscapes. One of its features is the wide-angle telephoto which has a shorter focal than traditional models.
The focal length. The focal length is the distance between the optic centre of the referring lens and the sensor. This is why the wide-angle lens are those which are less than 50 mm long.
The wide-angle lens differs according to the camera. In 35 mm or full-frame cameras a 50 mm lens is considered as a wide-angle, while in other cameras the wide-angle is smaller.
What is the most suitable lens? In wide-angle photography, the suitable lens is easily findable, as its length is show by every producer on the lens. In a world of Canonists and Nikonists, many solutions may be found.
What does the wide-angle lens need to? It is the lens that is mostly similar to human eye perception in the complete vision of a picture. It shows objects and people farther than they actually are. These lenses are suitable to conceptual photography, that has to show an abstract concept or an idea.
The picture angle. In wide-angle pics, the angle is extremely important, as it represents the width of the shot scene. The shorter is the focal length, the bigger is the picture angle. Those who looks for a lens whose angle is the closest to the human eye have to choose a 28-mm-focal-length lens. From this focal on, e.g. with a 15 mm, pictures with wider horizons may be obtained.
The Depth of field and perspective. Lenses that have a focal shorter than 50 mm give a far bigger perception of depth of field. With such a depth, the photophrapher gets a remarkable focus on all the elements of his/her composition. Perspective is another interesting element, typical of wide-angle photography, resulting from the distance between the observer and the thing observed, cheating human eye perception. By exploiting reflexes and right lights, some effects and perspective games, pics may be taken that highlight the foreground subject, and distance the background. Those pics have a great aesthetic impact, thanks to depth of field and a bigger angle.