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For 6/6 = 1.0 acuity, the size of a letter on the Snellen chart or Landolt C chart is a visual angle of 5 arc minutes (1 arc min = 1/60 of a degree), which is a 43 point font at 20 feet. [10] By the design of a typical optotype (like a Snellen E or a Landolt C), the critical gap that needs to be resolved is 1/5 this value, i.e., 1 arc min.
Snellen chart. Purpose. Snellen chart is used to estimate visual acuity (last three rows are 20/15, 20/13 and 20/10) A Snellen chart is an eye chart that can be used to measure visual acuity. Snellen charts are named after the Dutch ophthalmologist Herman Snellen who developed the chart in 1862 as a measurement tool for the acuity formula ...
An input unit can be converted to any number of output units—the outputs are specified as a "combination" by separating unit codes with a space (" ") or a plus (" + "). Using a space as a separator does not work if any of the unit codes contains a space. For example, each of the following converts 1.2 km 2 to acres, square yards, and hectares.
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 ...
≡ 1 ft/(h⋅s) = 8.4 6 × 10 −5 m/s 2: foot per minute per second: fpm/s ≡ 1 ft/(min⋅s) = 5.08 × 10 −3 m/s 2: foot per second squared: fps 2: ≡ 1 ft/s 2 = 3.048 × 10 −1 m/s 2: gal; galileo: Gal ≡ 1 cm/s 2 = 10 −2 m/s 2: inch per minute per second: ipm/s ≡ 1 in/(min⋅s) = 4.2 3 × 10 −4 m/s 2: inch per second squared ...
Although the most common medium format film, the 120 roll, is 6 cm (2.4 in) wide, and is most commonly shot square, the most common "medium-format" digital sensor sizes are approximately 48 mm × 36 mm (1.9 in × 1.4 in), which is roughly twice the size of a full-frame DSLR sensor format.
The template is intended for conversion of heights specified in either metres or in feet and inches. Template parameters [Edit template data] Parameter Description Type Status Metres m metre metres meter meters The height in metres. Do not use if feet and inches are specified. Number optional Centimetres cm centimetre centimetres centimeter centimeters The height in centimetres. Do not use if ...
The stokes (St) is a unit of kinematic viscosity equal to 1 cm 2 ⋅s −1 (100 mm 2 ⋅s −1). [3] The stilb (sb) is a unit of luminance equal to 1 cd⋅cm −2 (10 kcd⋅m −2). [4] The phot (ph) is a unit of illuminance equal to 1 lm⋅cm −2 (10 klx). [3] The rayl is a unit of specific acoustic impedance, equal to 1 dyn⋅s⋅cm −3 (10 ...