focusing screen

plural focusing screens

1. artsA flat translucent material found in a system camera that allows the photographer to preview the framed image in a viewfinder.

   You can always see the covered area on the focusing screen regardless what the subject distance might be or what close-up accessories are used.

   2012, Ernst Wildi, The Medium Format Advantage, →ISBN, page 183

   2 more examples

   Once the microgrid and split-image rangefinder became the major focusing controls, the focusing screen itself became a secondary or even tertiary focusing area and was/is generally ignored by many users.

   1993 July, Herbert Keppler, “SLR: Have manufacturers fouled up viewing screens for technological progress?”, in Popular Photography, volume 57, number 3, page 17

   This is because the reflex mirror in some SLR cameras is not quite long enough to provide full illumination of the entire focusing screen with the image from a telescope. Fortunately, such reduced illumination of the focusing screen will not affect your photograph.

   2012, Jeffrey R. Charles, Practical Astrophotography, →ISBN