The NT-4D, a surveying instrument also known as a theodolite, was manufactured by the Nikon Corporation. Used between 1988 and 1996 for both horizontal and vertical angle surveying, it was the third generation of the NT series, which was introduced in 1967.
General Features
The Nikon NT-4D was constructed of a one-piece, heavy-duty metal body with a detachable tribrach, which was used to level the top plate when mounted on a tripod. It also included equal-height standards for the addition of an optional electromagnetic distance measurement (EDM) apparatus.
Lens
This surveying instrument included a high-power, 30x telescope with a conveniently-located optical plummet system which was used to center the instrument. It also offered an extra-wide view field with an objective of up to 45 mm.
Dimensions
The Nikon NT-4D included a 30-inch plate vial and a direct digital readout of up to 3 inches. The setting accuracy of the vertical-angle compensator was 1 inch.
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