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Once limited to military and governmental applications, first-generation night vision equipment is now available for civilian use at a price affordable to many. Night vision devices find practical applications in boating safety, wildlife observation and night photography as well as by forming an unobtrusive part of home security... more »
Many people fear vision can be damaged by even the weakest lasers, such as those used in DVD drives. Of the four classes of lasers commonly used, two are officially considered harmless and two present either a genuine risk or the threat of immediate harm. Laser pointers fall into into a gray area of hazard, unlikely to cause damage... more »
A camera lens is the "eye" of a camera, allowing it to see the outside world. It also works a lot like a human eye, in that light passes through the lens and is focused on the film or image sensor of a digital camera. This light carries the images that both you and camera see.
A lens has several elements inside a metal barrel. Each... more »
Twinwood Festival takes place at the RAF Twinwood Airfield and Twinwood Arena, near Bedford. The festival features several different orchestras and performers, as well as tributes to old favourites such as Glenn Miller, Frank Sinatra and Elvis Presley. It also incorporates the annual Glenn Miller Festival of swing, jazz and jive. The... more »
Most digital cameras are identified by a megapixel rating that shows how large of an image they can capture. Before there were high megapixel ratings cameras where usually identified as having the VGA resolution. While most digital cameras and other electronic devices that contain cameras no longer use the outdated VGA standard there... more »
If anyone's ever handed you a pair of binoculars and said, "Look at that!" and you've held them to your eyes and have seen an unclear image, it's... more »
Binoculars come in many sizes and shapes, and prices vary from less than $50 to well over $1,000. more »
Combining the viewing capabilities of binoculars with the picture-taking abilities of cameras makes a great idea. Digital camera binoculars may... more »
Observing the stars is a hobby that requires good equipment if you plan on getting the most out of it. Astronomy can be done from home or while... more »
Stabilized binoculars will steady your view, and for certain hobbies these enhance the viewing experience. Looking at the stars, bird watching or... more »
A typical Porro prism binoculars design
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 with binocular vision when viewing distant objects. Most are sized to be held using both hands, although sizes vary widely; opera glasses are small, low-power binoculars for use at performance events. Many different abbreviations are used for binoculars, including glasses, 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 viewers eyes from slightly different viewpoints, produce a merged view with depth perception. 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, even at greater distances where depth perception is not apparent.
Optical design
Galilean binoculars
Galilean binoculars
Almost from the invention of the telescope in the 17th century the advantages of mounting two of them side by side for binocular vision seems to have been explored."europa"> — The Early History of the Binocular Most early binoculars used Galilean optics; that is they used a convex objective and a concave eyepiece lens. The Galilean design has the advantage of presenting an erect image but has a narrow field of view and is not capable of very high magnification. This type of construction is still used in very cheap models and in opera glasses or theater glasses.
Prism binoculars
Double Porro prism design
Abbe-Koenig "roof prism" design
An improved image and higher magnification can be achieved in a construction binoculars employing Keplerian optics, where the image formed by the objective lens is viewed through a positive eyepie read more at » http://en.wikipedia.org/wiki/Binoculars
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