Photographic reproduction of out-of-focus and distorted ocular imagery

The necessary settings and parameters were determined for ordinary camera a nd lens systems to faithfully reproduce out-of-focus and distorted imagery as it falls upon the retina of the human eye. Theoretic considerations of b oth geometric and physical optics were used to calculate the 'relative blur ' and distortion produced by refractive error added to ordinary camera lens es as opposed to refractive error in an arbitrary thick-lens optical system bounded by air and fluid (i.e. the eye). In both the camera and the eye, ' relative blur' was determined to be directly proportional to dioptric defoc us and to aperture size, and effectively independent of the Focal length. D istortion of imagery was also Found to be independent of the focal length. Photographs corroborate the theoretic findings. A given amount of relative blur, however, appeared somewhat greater when recorded on photographic film than when appreciated by the human eye. The Stiles-Crawford effect, the ch romatic aberration of the eye, and neural processing probably each contribu te to this difference. Previous investigators have grossly exaggerated blur and distortion in photographs intended to simulate ocular imagery and have drawn misleading conclusions from their results. (C) 2001 Elsevier Science Ltd. All rights reserved.