Nearer moving bodies appear faster than remote ones
Equal true motions differ in seen speed because they sweep different amounts of the visual field
Continuing the study of apparent motion, Leonardo asserts that among bodies moving equally the nearer appears faster and the more remote slower. His reason is the visual field: a remote body moving as fast as a near one sweeps a smaller part of the field in the same time, so whichever covers more field looks quicker. A large diagram places the eye at a and, with lettered points b, e, n, c, f, g, compares a body moving d–c against one moving e–f.
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Nearer looks faster, remoter looks slower
Among things that move equally, the one nearer to the eye will appear the faster, and the one more remote will appear the slower. With real speed equal, distance alone changes the perceived rate.
Perceived speed set by field of view swept
Everything that moves is seen in the field where it ends; a remote body in motion equal to a near one occupies less field in the same time. Covering more field makes a body look faster. With a as the eye, d moving to c appears slow because it occupies only a small space.