Glass that has been given a coarse surface finish, usually with a fine abrasive, to be used as the viewfinder or viewing screen in some analogue cameras. The frosted surface aids the scattering of light coming through the lens and reproduces the image for the photographer to compose and focus it. Such a viewing screen is used in large-format and some medium-format cameras, where the size of the ground glass plate matches the size of the film used in the camera. The plate may feature lines to aid composition.
ground glass
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