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1889 Arthur Krebs & Jean Rey periscope for the French submarine Gymnote. Periscopes allow a submarine, when submerged at a relatively shallow depth, to search visually for nearby targets and threats on the surface of the water and in the air. When not in use, a submarine's periscope retracts into the hull.
At depths below periscope depth submarines determine their position using: Dead reckoning course information obtained from the ship's gyrocompass , measured speed and estimates of local ocean currents, this could also be considered an estimated position as long as the ocean current is computed in.
The hyperfocal distance has a property called "consecutive depths of field", where a lens focused at an object whose distance from the lens is at the hyperfocal distance H will hold a depth of field from H/2 to infinity, if the lens is focused to H/2, the depth of field will be from H/3 to H; if the lens is then focused to H/3, the depth of ...
With increasing magnification, the depth of field – the distance between the nearest and the farthest objects that are in acceptably sharp focus in an image – decreases. The depth of field reduces quadratic with the magnification, so compared to 7× binoculars, 10× binoculars offer about half (7² ÷ 10² = 0.49) the depth of field.
In 3D computer graphics and computer vision, a depth map is an image or image channel that contains information relating to the distance of the surfaces of scene objects from a viewpoint. The term is related (and may be analogous) to depth buffer , Z-buffer , Z-buffering , and Z-depth . [ 1 ]
The hyperfocal distance has a property called "consecutive depths of field", where a lens focused at an object whose distance from the lens is at the hyperfocal distance H will hold a depth of field from H/2 to infinity, if the lens is focused to H/2, the depth of field will be from H/3 to H; if the lens is then focused to H/3, the depth of ...
Submarines can be spotted from aircraft when they're operating at a shallow depth pretty much anywhere where the water is clear (which is why they generally stay bellow periscope depth) so this is isn't all that rare. Nick Dowling 03:10, 3 August 2008 (UTC) Support-- nicer image than the failed candidate, good encyc. value. Not a common photo ...
In photographic optics, the Zeiss formula is a supposed formula for computing a circle of confusion (CoC) criterion for depth of field (DoF) calculations. The formula is c = d / 1730 {\displaystyle c=d/1730} , where d {\displaystyle d} is the diagonal measure of a camera format, film, sensor, or print, and c {\displaystyle c} the maximum ...