magnification [OPTICS]—The ratio of the size of an image to the size of the object.

magnification, angular [OPTICS]—The ratio of the angle subtended at the eye by the image formed by an optical device, to the angle subtended at the eye by the object itself without the optical device. This is convenient to use in cases where a distance in the object cannot be measured to express a linear magnification, as in the use of a telescope.

magnification, linear [OPTICS]—The ratio of a linear quantity in the image to a corresponding linear quantity in the object. Linear magnification may be lateral or longitudinal. Lateral magnification—The ratio of a length in the image. perpendicular to the lens axis, to a corresponding length in the object. Longitudinal magnification—The ratio of a length in the image along the axis to a corresponding length in the object.

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Source: NSPS “Definitions of Surveying and Related Terms“, used with permission.

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