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The micrometre (Commonwealth English as used by the International Bureau of Weights and Measures; [1] SI symbol: μm) or micrometer (American English), also commonly known by the non-SI term micron, [2] is a unit of length in the International System of Units (SI) equalling 1 × 10 −6 metre (SI standard prefix "micro-" = 10 −6); that is, one millionth of a metre (or one thousandth of a ...
The '-2' represents the pattern of the points tested. [3] They include: 10-2: Measures 10 degrees temporally and nasally and tests 68 points. Used for macula, retinal and neuro-ophthalmic conditions and advanced glaucoma [4] 24-2: Measures 24 degrees temporally and 30 degrees nasally and tests 54 points.
A simple and efficient way to state acuity is by converting the fraction to a decimal: 6/6 then corresponds to an acuity (or a Visus) of 1.0 (see Expression below), while 6/3 corresponds to 2.0, which is often attained by well-corrected healthy young subjects with binocular vision.
A micrometer, sometimes known as a micrometer screw gauge, is a device incorporating a calibrated screw widely used for accurate measurement of components [1] in mechanical engineering and machining as well as most mechanical trades, along with other metrological instruments such as dial, vernier, and digital calipers.
For this purpose scope mounts are sold with varying degrees of tilt, but some common values are: 3 mrad, which equals 3 m at 1000 m (or 0.3 m at 100 m) 6 mrad, which equals 6 m at 1000 m (or 0.6 m at 100 m) 9 mrad, which equals 9 m at 1000 m (or 0.9 m at 100 m) With a tilted mount the maximum usable scope elevation can be found by:
Degrees, therefore, are subdivided as follows: 360 degrees (°) in a full circle; 60 arc-minutes (′) in one degree; 60 arc-seconds (″) in one arc-minute; To put this in perspective, the full Moon as viewed from Earth is about 1 ⁄ 2 °, or 30 ′ (or 1800″). The Moon's motion across the sky can be measured in angular size: approximately ...
Metric system. A kilogram mass and three metric measuring devices: a tape measure in centimetres, a thermometer in degrees Celsius, and a multimeter that measures potential in volts, current in amperes and resistance in ohms. The metric system is a decimal -based system of measurement. The current international standard for the metric system is ...
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 ...