
1) Photography equipment
Found on
https://www.crosswordclues.com/clue/focusing-screen

A focusing screen is a flat translucent material, either a ground glass or fresnel lens, found in a system camera that allows the user of the camera to preview the framed image in a viewfinder. Often, focusing screens are available in variants with different etched markings for various purposes. For instance, `overall matte` focusing screens wit.....
Found on
http://en.wikipedia.org/wiki/Focusing_screen

(from the article `photography, technology of`) The ground-glass (now mostly grained plastic) screen is the most direct way of viewing the image for framing and for sharpness control. The screen ...
Found on
http://www.britannica.com/eb/a-z/f/41

Used for focusing on a subject or composing a picture; the focusing screen is located at a position equivalent to that of the film plane. To provide dispersion, a matte field made of specially ground glass or plastic is generally used for focusing screens
Found on
http://www.encyclo.co.uk/local/21048

Used for focusing on a subject or composing a picture; the focusing screen is located at a position equivalent to that of the film plane. To provide dispersion, a matte field made of specially ground glass or plastic is generally used for focusing screens.
Found on
http://www.rodsmith.org.uk/photographic%20glossary/rods%20photographic%20gl

Glass or plastic screen set at the camera's image-forming plane, where the image can be viewed and focused. (see Finder)
Found on
https://www.encyclo.co.uk/local/20176
No exact match found.