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  2. Mirror image - Wikipedia

    en.wikipedia.org/wiki/Mirror_image

    A mirror image (in a plane mirror) is a reflected duplication of an object that appears almost identical, but is reversed in the direction perpendicular to the mirror surface. As an optical effect , it results from specular reflection off from surfaces of lustrous materials, especially a mirror or water .

  3. Focal length - Wikipedia

    en.wikipedia.org/wiki/Focal_length

    The focal point F and focal length f of a positive (convex) lens, a negative (concave) lens, a concave mirror, and a convex mirror.. The focal length of an optical system is a measure of how strongly the system converges or diverges light; it is the inverse of the system's optical power.

  4. Image formation - Wikipedia

    en.wikipedia.org/wiki/Image_formation

    The ratio of the height of the image to the height of the object is the magnification. The spatial extent of the image surface and the focal length of the lens determines the field of view of the lens. Image formation of mirror these have a center of curvature and its focal length of the mirror is half of the center of curvature.

  5. f-number - Wikipedia

    en.wikipedia.org/wiki/F-number

    The f-number N is given by: = where f is the focal length, and D is the diameter of the entrance pupil (effective aperture).It is customary to write f-numbers preceded by "f /", which forms a mathematical expression of the entrance pupil's diameter in terms of f and N. [1]

  6. Virtual image - Wikipedia

    en.wikipedia.org/wiki/Virtual_image

    The image in a plane mirror is not magnified (that is, the image is the same size as the object) and appears to be as far behind the mirror as the object is in front of the mirror. A diverging lens (one that is thicker at the edges than the middle) or a concave mirror forms a virtual image. Such an image is reduced in size when compared to the ...

  7. Cardinal point (optics) - Wikipedia

    en.wikipedia.org/wiki/Cardinal_point_(optics)

    In such systems an object ray parallel to the optical axis is conjugate to an image ray parallel to the optical axis. A system is focal if an object ray parallel to the axis is conjugate to an image ray that intersects the optical axis. The intersection of the image ray with the optical axis is the focal point F ′ in image space. Focal ...

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  9. Real image - Wikipedia

    en.wikipedia.org/wiki/Real_image

    A real image is the collection of focus points actually made by converging/diverging rays, while a virtual image is the collection of focus points made by extensions of diverging or converging rays. In other words, a real image is an image which is located in the plane of convergence for the light rays that originate from a given object.