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Depression range finder
Videos
The depression range finder was a fire control device used to determine the target's position by observing range and bearing and to calculate firing solutions when gun laying in coastal artillery. It
A Watkin depression position finder on a range dial in a position finding cell, Dover Castle, England
A Watkin depression position finder on a range dial in a position finding cell, Dover Castle, England
O represents the observer, at a distance OM above sea level (and the target on the sea). The range to the target is determined by taking the cotangent
O represents the observer, at a distance OM above sea level (and the target on the sea). The range to the target is determined by taking the cotangent of the depression angle d times the height of the instrument OM, to yield the range MP. But due to the curvature of the Earth, the true range is MT. To achieve this, the DPF instrument adjusts the observer's height from OM to ON, and then correctly measures the range as NT. Alternatively, the depression angle could be adjusted to
An American DPF (left) and azimuth scope (right) in use
An American DPF (left) and azimuth scope (right) in use
An American Warner-Swasey DPF, illustration from a 1910 manual
An American Warner-Swasey DPF, illustration from a 1910 manual
Rangefinder
Videos
A rangefinder is a device used to measure distances to remote objects. Originally optical devices used in surveying, they soon found applications in other fields, such as photography, the military, an
Depression range finder
…by observing range and bearing and to calculate firing solutions when gun laying in coastal artillery. It was the main component of a vertical base rangefinding system. It was necessitated by the introduction of rifled artillery from the mid-19th century onwards, which had much greater ranges than the old…
Portable German stereoscopic rangefinder from WWII
Portable German stereoscopic rangefinder from WWII
The coincidence rangefinder of the Polish destroyer ORP Wicher
The coincidence rangefinder of the Polish destroyer ORP Wicher
Laser rangefinder
Laser rangefinder
Second World War German range finding tower at La Corbière, Jersey
Second World War German range finding tower at La Corbière, Jersey