ground-glass screen
Quick Summary
A ground-glass screen is a surface made of glass that has been etched or abraded to create a light-diffusing texture. In optics, particularly in cameras, this screen serves as a direct method for viewing the image formed by the lens. It localizes the image plane, allowing photographers to frame their shots and precisely control focus.12
While modern cameras often use grained plastic, the principle remains the same. The ground-glass screen helps the eye assess sharpness, though aids like split-image wedges or microprism areas are often incorporated to improve accuracy, as the eye can struggle to detect minor unsharpness.2
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