What You Need To Know About Optics
The first experiments directed to give shooters optical aiming aids go back to the early 17th century
. For centuries, different optical aiming aids and primitive predecessors of telescopic sights were created that had practical or performance limitations.
The first documented telescopic rifle sight was invented between 1835 and 1840. In a book titled The Improved American Rifle, written in 1844, John R. Chapman documents the first telescopic sights made by Morgan James of Utica, NY. Chapman, the author, being a civil engineer, gave James the concepts and some of the design, whereupon they produced the Chapman-James sight. A bit later, in 1855, William Malcolm, of Syracuse, NY began producing his own sight. He did not steal the Chapman-James design. He did it the old-fashioned way: he worked for a telescope maker to learn how to make them, incorporated achromatic lenses, and made the windage and elevation adjustments more perfect. They were between 3X and 20X or greater. These and ones made by Mr. L.M. Amidon of Vermont were the standard during the Civil War.
A night vision device (NVD) is an optical instrument that allows images to be produced in levels of light approaching total darkness. They are most often used by the military and law enforcement agencies, but are available to civilian users. The term usually refers to a complete unit, including an image intensifier tube, a protective and generally water-resistant housing, and some type of mounting system. Many NVDs also include sacrificial lenses, IR illuminators, and telescopic lenses.
Night vision devices provide night fighters with the ability to see, maneuver and shoot at night or during periods of reduced visibility. The Army used two different types of NVDs - image intensifiers and thermals. Image-Intensifying Devices are based upon light amplification and must have some light available. These devices can amplify the available light from 2,000 to 5,000 times. Thermal Forward-Looking Infrared (FLIR) detectors - sometimes called "sensors" - work by sensing the temperature difference between an object and its environment. FLIR systems are installed on certain combat vehicles and helicopters.
Binoculars, field glasses or binocular telescopes are a pair of identical or mirror-symmetrical telescopes mounted side-by-side and aligned to point accurately in the same direction, allowing the viewer to use both eyes (binocular vision) when viewing distant objects. Most are sized to be held using both hands, although sizes vary widely from opera glasses to large pedestal mounted military models. Many different abbreviations are used for binoculars, including glasses, nocs, noculars, binos and bins.
Unlike a (monocular) telescope, binoculars give users a three-dimensional image: for nearer objects the two views, presented to each of the viewer's eyes from slightly different viewpoints, produce a merged view with an impression of depth. There is no need to close or obstruct one eye to avoid confusion, as is common with monocular telescopes. The use of both eyes also significantly increases the perceived visual acuity (resolution), even at greater distances where depth perception is not apparent.
The telescopic sight, more commonly known as a scope, has always been the true hunter's guide to game. The first experiments to give hunters a better chance at catching game dates back to the 1600's when they had the target and aiming aid held at the same level. Hunters have always tried to create some simple form of an optical aiming aid.
Over the centuries, they have tried using primitive magnifying glasses, short range telescopes, and even magnified dioptres, which is a curved mirror that magnifies things through light. But none of these had great success due to technical difficulties.
by: Chelsea McVey
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