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  2. Throw (projector) - Wikipedia

    en.wikipedia.org/wiki/Throw_(projector)

    Distance (D), Width (W), Throw Ratio (R) If the distance and width are known, calculate the throw ratio using the formula: R = D / W [1] If the screen width and throw ratio are known, calculate the distance using the equivalent formula: D = W x R. Although it is often stated as a single value (or range of values), throw ratio is a comparison of ...

  3. Guide number - Wikipedia

    en.wikipedia.org/wiki/Guide_number

    A scene will be properly illuminated for every combination of f‑stop and distance shown on this flash device's exposure calculation dial, each of which equals the same guide number. The guide number here (full power setting, ISO 100, and normal-angle coverage) is 37 for calculations made in meters (yellow arrow) and 120 for feet (orange).

  4. Rayleigh distance - Wikipedia

    en.wikipedia.org/wiki/Rayleigh_distance

    Rayleigh distance in optics is the axial distance from a radiating aperture to a point at which the path difference between the axial ray and an edge ray is λ / 4. An approximation of the Rayleigh Distance is Z = D 2 2 λ {\displaystyle Z={\frac {D^{2}}{2\lambda }}} , in which Z is the Rayleigh distance, D is the aperture of radiation, λ the ...

  5. 1951 USAF resolution test chart - Wikipedia

    en.wikipedia.org/wiki/1951_USAF_resolution_test...

    A USAF 1951 resolution chart in PDF format is provided by Yoshihiko Takinami. This chart should be printed such that the side of the square of the 1st element of the group -2 should be 10 mm long. USAF 1951 Resolution Target Further explanations and examples; Koren 2003: Norman Koren's updated resolution chart better suited for computer analysis

  6. Stadia mark - Wikipedia

    en.wikipedia.org/wiki/Stadia_mark

    This length is chosen so that there is a fixed, integer ratio between the difference of the rod readings and the distance from the telescope to the rod. This ratio is known as the stadia constant or stadia interval factor. Thus the formula for distance is D = kS. where D is distance from the telescope to the rod; k is the stadia constant

  7. Optical path length - Wikipedia

    en.wikipedia.org/wiki/Optical_path_length

    where n is the local refractive index as a function of distance along the path C. An electromagnetic wave propagating along a path C has the phase shift over C as if it was propagating a path in a vacuum , length of which, is equal to the optical path length of C .

  8. Range of a projectile - Wikipedia

    en.wikipedia.org/wiki/Range_of_a_projectile

    The path of this projectile launched from a height y 0 has a range d.. In physics, a projectile launched with specific initial conditions will have a range.It may be more predictable assuming a flat Earth with a uniform gravity field, and no air resistance.

  9. Free-space path loss - Wikipedia

    en.wikipedia.org/wiki/Free-space_path_loss

    Free-space loss increases with the square of distance between the antennas because the radio waves spread out by the inverse square law and decreases with the square of the wavelength of the radio waves. The FSPL is rarely used standalone, but rather as a part of the Friis transmission formula, which includes the gain of antennas. [3]