Shedding New Light on Darkroom Illumination
Rod vision has a spectral response peaking at 507 nanometers, often termed "scotopic vision." The less sensitive foveal cone vision peaks at 555 nanometers, and is usually called "photopic vision." Although less sensitive in the dark, the cones provide much better visual acuity than the rods, and are the bases for color vision.
Because some darkroom operations like splicing or reading job tickets require reasonable visual acuity, the light level sometimes may be sufficient to utilize both rod and cone vision-a middle or "mesopic" visual response.
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