True motion seen when the object lies beyond the pinhole card
Visual rays through a single hole; with a as the eye, a body moves along a b c
Concluding the pinhole study, Leonardo notes that when the moving object lies beyond the perforated paper, the eye sees the object's true motion. A diagram traces visual rays passing through a single hole in a card set between the eye and the moving body, with lettered rays a f, b e, c d. He adds: let a move along a b c.
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Object beyond the card shows its true motion
If the object's motion takes place on the far side of the perforated paper, then the eye sees the true motion of the object. The reversal seen with the object in front of the card no longer occurs.
Visual rays through a single hole
A card pierced by one hole stands between the eye and the moving body, and the visual rays a f, b e, c d cross through the hole. Let us say that a moves along a b c.