Letter | Published:

Luminous Efficiency of Rays entering the Eye Pupil at Different Points

Nature volume 139, page 246 (06 February 1937) | Download Citation



WE have shown1 that the impression of brightness produced by a light ray which forms an image on a fixed area of the retina depends in high degree on the position of entry of the ray in the eye pupil. For the ratio of the apparent brightness for peripheral entry to the apparent brightness for central entry, values as low as 0.2 were found for white light and foveal vision. The following new features of the phenomenon have been revealed by later work:

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  1. 1.

    and , Proc. Roy. Soc., B, 112, 428 (1933).

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  1. National Physical Laboratory, Teddington, Middlesex. Dec. 24.

    • W. S. STILES
    •  & B. H. CRAWFORD


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