Looming Looming Looming is a term found in the study of perception, as it relates directly to psychology. Looming refers to the rapid expansion in the size of any given image. As the image becomes increasingly large on the perceiver's retina, i.e., when an object "looms", there is an automatic physiological response to perceive the object as an approaching object or surface, instead of one that is stationary or receding. Evidence indicates that looming perception is not limited to the visual modality, but can occur due to auditory or even tactile stimuli. There is a different type of mirage that is
Depth of field to object size is independent of focal length, and depends only on the object size and its distance from the subject. This discussion thus far has assumed a symmetrical lens for which the entrance and exit pupils coincide with the object and image nodal planes, and for which the pupil magnification is unity. Although this assumption usually is reasonable for large-format lenses, it often is invalid for medium- and small-format lenses. For an asymmetrical lens, the DOF ahead of the subject distance and the DOF beyond the subject distance are given by and where formula_25 is the pupil magnification. Combining