Boing Boing on MSN7d
Hidden for 175 years: Photographer's mysterious "witch mirror" 3D self-portrait emergesFrench photography pioneer Charles Nègre created a 3D self-portrait using a "witch's mirror" - a clever piece of 19th-century ...
In a ray diagram, a concave lens is drawn as a vertical line with inward facing arrows to indicate the shape of the lens.
In a ray diagram, a concave lens is drawn as a vertical line with inward facing arrows to indicate the shape of the lens.
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