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  2. Magnification - Wikipedia

    en.wikipedia.org/wiki/Magnification

    By convention, for magnifying glasses and optical microscopes, where the size of the object is a linear dimension and the apparent size is an angle, the magnification is the ratio between the apparent (angular) size as seen in the eyepiece and the angular size of the object when placed at the conventional closest distance of distinct vision: 25 ...

  3. Sign convention - Wikipedia

    en.wikipedia.org/wiki/Sign_convention

    The sign of the weight of a tensor density, such as the weight of the determinant of the covariant metric tensor. The active and passive sign convention of current, voltage and power in electrical engineering. A sign convention used for curved mirrors assigns a positive focal length to concave mirrors and a negative focal length to convex mirrors.

  4. Lens - Wikipedia

    en.wikipedia.org/wiki/Lens

    which is the ratio of the output beam width to the input beam width. Note the sign convention: a telescope with two convex lenses (f 1 > 0, f 2 > 0) produces a negative magnification, indicating an inverted image. A convex plus a concave lens (f 1 > 0 > f 2) produces a positive magnification and the

  5. Curved mirror - Wikipedia

    en.wikipedia.org/wiki/Curved_mirror

    The sign convention used here is that the focal length ... The magnification of a mirror is defined as the ... By convention, if the resulting magnification is ...

  6. Focal length - Wikipedia

    en.wikipedia.org/wiki/Focal_length

    For a thin lens in air, the focal length is the distance from the center of the lens to the principal foci (or focal points) of the lens.For a converging lens (for example a convex lens), the focal length is positive and is the distance at which a beam of collimated light will be focused to a single spot.

  7. Thin lens - Wikipedia

    en.wikipedia.org/wiki/Thin_lens

    Sign convention for Gaussian lens equation Parameter Meaning + Sign - Sign s o: The distance between an object and a lens. Real object Virtual object s i: The distance between an image and a lens. Real image Virtual image f: The focal length of a lens. Converging lens Diverging lens y o: The height of an object from the optical axis. Erect ...

  8. Telescopic sight - Wikipedia

    en.wikipedia.org/wiki/Telescopic_sight

    A magnification factor of 10, for example, produces an image as if one were 10 times closer to the object. The amount of magnification depends upon the application the telescopic sight is designed for. Lower magnifications lead to less susceptibility to shaking. A larger magnification leads to a smaller field of view.

  9. Abbe sine condition - Wikipedia

    en.wikipedia.org/wiki/Abbe_sine_condition

    When the imaging system obeys the Abbe sine condition, the ratio of the sines of these angles equal the (lateral absolute) magnification of the system. In optics , the Abbe sine condition is a condition that must be fulfilled by a lens or other optical system in order for it to produce sharp images of off-axis as well as on-axis objects.