Why stars seen through a pinhole appear diminished
The pupil images each whole star at every circle-size; three stars traced through hole n m versus circle K L
Leonardo explains that the whole pupil, at each of a series of ever-diminishing circles, can still see the entire body of a star, but sees it smaller the smaller the part of the light used. He restates that the images do not superimpose one on another. The main demonstration asks why the sky shows many bright stars, yet the same number seen through a tiny hole in paper held to the eye appear much reduced: taking the pupil as the larger circle K L, the three stars a b c enter by the lines d K e L, f K g L, h K i L; but when the eye can use only the part n m through the paper's hole, the same images enter by the six lines d n e m, f n g m, h n i m and appear smaller as n m is smaller than K L. Several bundled cone-diagrams occupy the right margin and upper corners.
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The pupil images the whole star at every diminishing circle
The whole pupil, with each of these circles from largest to smallest, successively and infinitely diminishing, can see the whole body of the star, but will see it the smaller the smaller the part of the light with which it sees it.
The images do not superimpose
The images do not superimpose one upon another.
Three stars through the full pupil K L versus the pinhole n m (a b c)
Taking the pupil as the larger circle K L, the impressions of the three stars a b c enter by the lines d K e L, f K g L, h K i L. When the eye can use only the part n m, because it must look through the hole in the paper, the same three star-images enter by the six lines d n e m, f n g m, h n i m and appear as much smaller as n m is smaller than K L.