"Lorraine Mirror Or Black Mirror"
Black Mirror or Lorrain Mirror, named after the painter Claude Lorrain (1602-1682) Black convex mirror in a case with a lid that allowed painters to see the landscape reduced to grayscale. The user, with his back to his subject, uses the mirror in the opposite direction but with attention and concentration equivalent to that of the photographer composing his subject in the viewfinder of his camera. https://www.lavalisearlesienne.com/product-page/miroir-de-lorrain-ou-miroir-noir 
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