Search results
Results from the WOW.Com Content Network
A calculation using Airy discs as point spread function shows that at Dawes' limit there is a 5% dip between the two maxima, whereas at Rayleigh's criterion there is a 26.3% dip. [3] Modern image processing techniques including deconvolution of the point spread function allow resolution of binaries with even less angular separation.
Since the average value of is 1/2, the transmission coefficient becomes I I 0 = 1 2 . {\displaystyle {\frac {I}{I_{0}}}={\frac {1}{2}}.} In practice, some light is lost in the polarizer and the actual transmission will be somewhat lower than this, around 38% for Polaroid-type polarizers but considerably higher (>49.9%) for some birefringent ...
It is straightforward to construct with ruler and compasses. It is the angle of the equilateral triangle or is 1 / 6 turn. 1 Babylonian unit = 60° = π /3 rad ≈ 1.047197551 rad. hexacontade: 60: 6° The hexacontade is a unit used by Eratosthenes. It equals 6°, so a whole turn was divided into 60 hexacontades. pechus: 144 to 180: 2 ...
Atmospheric refraction of the light from a star is zero in the zenith, less than 1′ (one arc-minute) at 45° apparent altitude, and still only 5.3′ at 10° altitude; it quickly increases as altitude decreases, reaching 9.9′ at 5° altitude, 18.4′ at 2° altitude, and 35.4′ at the horizon; [4] all values are for 10 °C and 1013.25 hPa ...
This table shows the diagonal, horizontal, and vertical angles of view, in degrees, for lenses producing rectilinear images, when used with 36 mm × 24 mm format (that is, 135 film or full-frame 35 mm digital using width 36 mm, height 24 mm, and diagonal 43.3 mm for d in the formula above). [16]
The nautical mile (nmi) was originally defined as the arc length of a minute of latitude on a spherical Earth, so the actual Earth circumference is very near 21 600 nmi. A minute of arc is π 10 800 of a radian . A second of arc, arcsecond (arcsec), or arc second, denoted by the symbol ″, [ 2] is 1 60 of an arcminute, 1 3600 ...
The azimuth is the angle formed between a reference direction (in this example north) and a line from the observer to a point of interest projected on the same plane as the reference direction orthogonal to the zenith. An azimuth ( / ˈæzəməθ / ⓘ; from Arabic: اَلسُّمُوت, romanized : as-sumūt, lit. 'the directions') [ 1] is the ...
Calcaneal fracture. A calcaneal fracture is a break of the calcaneus (heel bone). [ 1] Symptoms may include pain, bruising, trouble walking, and deformity of the heel. [ 1] It may be associated with breaks of the hip or back.