focal plane

noun

, Optics.

a plane through a focal point and normal to the axis of a lens, mirror, or other optical system. Compare principal plane.
the transverse plane in a telescope where the real image of a distant view is in focus.

focal plane

the plane that is perpendicular to the axis of a lens or mirror and passes through the focal point
the plane in a telescope, camera, or other optical instrument in which a real image is in focus

First recorded in 1890–95

The total movement of the half-object glass is double the distance between the star images in the focal plane.

Rays of light from some distant object are converged by the objective (D) and form an inverted image (ab) at the focal plane (F).

If any error of convexity exists in the plate, the focal plane is disturbed, and the eyepiece must be moved out.

The photographer must change the plate, set the focal plane shutter, and press the release.

The focal plane of the light is elevated 93 ft. above high water.

April 25, 2024firkin

[fur-kin ]

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