Ground glass

The ground glass usually contains precise markings to show the camera operator the boundaries of the frame or the center reticle, or any other important information.

This hides unsightly details of the lamp and fixture without blocking its light, yielding a softer illumination without giving hard shadows.

[1][2] The Guy de Maupassant short story "La Confession" concerns a jealous girl who poisons her older sister's suitor by inserting ground-up glass into cake.

Captain F. C. Briggs, adjutant to General Reginald Dyer, died of 'powdered glass' poisoning before he could give evidence to the Hunter Commission examining the Jallianwalla Bagh massacre.

[5] This article was originally based on "Ground glass back" in Camerapedia, retrieved at an unknown date under the GNU Free Documentation License.