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limiting magnitude with 12.5" reflector is 14.5; 7 Suburban/urban transition 4.6–5.0 18.00–18.5 light pollution makes the entire sky light gray; strong light sources are evident in all directions; clouds are brightly lit; the Milky Way is nearly or totally invisible; M31 and M44 may be glimpsed, but with no detail
The Richter scale [1] (/ ˈ r ɪ k t ər /), also called the Richter magnitude scale, Richter's magnitude scale, and the Gutenberg–Richter scale, [2] is a measure of the strength of earthquakes, developed by Charles Richter in collaboration with Beno Gutenberg, and presented in Richter's landmark 1935 paper, where he called it the "magnitude scale". [3]
Snellen chart. The Snellen chart, which dates back to 1862, is also commonly used to estimate visual acuity.A Snellen score of 6/6 (20/20), indicating that an observer can resolve details as small as 1 minute of visual angle, corresponds to a LogMAR of 0 (since the base-10 logarithm of 1 is 0); a Snellen score of 6/12 (20/40), indicating an observer can resolve details as small as 2 minutes of ...
In digital photography, the image sensor format is the shape and size of the image sensor. The image sensor format of a digital camera determines the angle of view of a particular lens when used with a particular sensor. Because the image sensors in many digital cameras are smaller than the 24 mm × 36 mm image area of full-frame 35 mm cameras ...
Under optimal conditions of good illumination, high contrast, and long line segments, the limit to vernier acuity is about 8 arc seconds or 0.13 arc minutes, compared to about 0.6 arc minutes (6/4) for normal visual acuity or the 0.4 arc minute diameter of a foveal cone.
An illustration of light sources from magnitude 1 to 3.5, in 0.5 increments. In astronomy, magnitude is a measure of the brightness of an object, usually in a defined passband. An imprecise but systematic determination of the magnitude of objects was introduced in ancient times by Hipparchus. Magnitude values do not have a unit.
2–5 km/h 0.3–1.5 m/s 0–1 ft 0–0.3 m Ripples with appearance of scales are formed, without foam crests Direction shown by smoke drift but not by wind vanes 2 Light breeze 4–6 knots 4–7 mph 6–11 km/h 1.6–3.3 m/s 1–2 ft 0.3–0.6 m Small wavelets still short but more pronounced; crests have a glassy appearance but do not break
In JPEG, 4:4:2 and 4:2:1 half the vertical resolution of Cb compared to 4:4:4 and 4:4:0. [19] In another version of 4:2:1, Cb horizontal resolution is half that of Cr (and a quarter of the horizontal resolution of Y). 4:1:0.5 or 4:1:0.25 are variants of 4:1:0 with reduced horizontal resolution on Cb, similar to VHS quality.