PERSPECTIVE (Fr., Perspective; Ger., Pers pektive) Assuming that lenses are free from distortion, that they are opposite the centre of the plate, and that the plate is vertical, all lenses will give the same drawing or perspective from the same standpoint. If the focal lengths vary, more or less of the subject will be included, but such objects as are rendered by all will be identical in perspective.
A good deal of misapprehension has arisen from the fact that, more often than not, lenses include far more than can be seen clearly by the eye from the same standpoint. If a lens of very short focus is used on a large plate, the resulting picture is sometimes said to have incorrect per spective. It is only incorrect in the sense that the eye, placed in the same position as the lens, is not adapted for seeing the same amount of the subject. If the eye could include as much as the lens, it would see precisely what the lens renders. As, however, photographs are made to be looked at, it is desirable to avoid this " unnatural " perspective. This can be done by using lenses of such focal length that the pictures they draw approximate to those seen by the eye. When a lens has included so much that the effect to the eye appears strained and unnatural, the exaggeration may be removed by trimming away more or less of the outer parts. Another cause of abnormal drawing is the takiug of what was originally d. subject at one side of a picture and presenting it apart, as though the lens had originally been directed straight at it.
The point of view has a great deal to do with the perspective or " drawing " of an object. In every case the perspective will be accurate for that particular viewpoint, but the resulting arrangement will not necessarily be pleasing simply because it is correct. So that, inasmuch as the photographer does not have to concern himself at all with the correctness of the " draw ing," he must direct his efforts to the consider ation of such d. point of view, and the use of such a lens, that the result shall appear natural and pleasing to the eye.
The unnatural appearance of a wide-angle picture is accentuated if the whole of the sub ject is enlarged. This is because a large print is generally viewed at a greater distance than a small one, whereas the shorter the focal length of the lens employed the closer to the print should the eye be placed for the perspective to appear natural. The unnatural appearance is also emphasised when some of the objects in cluded were comparatively close to the lens. For example, an upright picture on a near wall may apparently be elongated into a horizontal one, and only assumes its natural proportions if it can be viewed at a distance something like that of the focal length of the lens used. (See also " Perspective, False.")