WHAT ARE OPTICS?

Put simply, optics are instruments that manipulate light and deliver it to the eye or to digital or chemical film. This includes instruments that use lenses or mirrors in the form of monoculars, scopes, binoculars, telescopes, and microscopes.

Here are some quick definitions...

BINOCULARS: used to magnify and intensify light simulataneously to both eyes; used for both sky (astronomical) and land (terrestrial) viewing

SPOTTING SCOPES and MONOCULARS: optical instruments designed to intensify and magnify images for one eye; Spotting Scopes are frequently used for birdwatching, terrestrial viewing, and target confirmation on a shooting range or in the field.

TELESCOPES: devices that magnify and intensify light, primarily designed for astronomical use.

NIGHT-VISION: devices equipped with night-vision capabilites include electronic components that further amplify images that are optically gathered, and display them on a screen located either within the instrument behind a lens, or on an LCD panel. Night vision optics may also process invisible infrared images and display those images as visible images on a screen. Night-vision instruments are notable for allowing the user to see objects clearly in almost total darkness.

What do the numbers on a telescope or set of binoculars mean?

Usually an optical instrument is classified with two numbers, one "multipled" by another, ie, 7 x 35 or 10 x 50.

In the preceding examples, the "7" or "10" refer to the magnification power of the device, and the "35" and "50" refer to the millimeter diameter of the objective or largest lens (the lens farthest away from the eye on the other end.) Magnification is simply the factor of increase in size when viewing an object, that is, the moon viewed through 7x would appear 7 times larger than through the naked eye. The second number, the size of the objective lens, signifies the light-gathering power of the instrument; for example, if I drag a pipe 2 inches in diameter through a lake, more water will go through it than if I drag a pipe 1 inch in diamater through the same water. More light goes into the larger opening (or aperture), and as a result more light is processed through the instrument and the resulting image is brighter to the eye. This is very important when considering astronomical viewing. One of the largest misconceptions about using telescopes is that they should have a stronger magnification power, as if heavenly objects were very "tiny" in the sky and had to be powerfully enlarged to be visible. In actuality, most objects of interest to astronomers (professional and amateur) are NOT small, but rather very DIM in the sky. This means that a telescope is a "rheostat", a light-intensifying device. The larger or wider the main aperture is on any given telescope, the more "light-gathering" it is capable of, and the more you can see in the night sky. A good example would be the familiar star-cluster named the Pleiades. To the naked eye seven to nine stars can be seen (depending on your eyesight), but through a good pair of binoculars dozens of stars spring into view in the same part of the sky...and through a powerful telescope, hundreds!

As you browse the optical instruments on our website, you may have additional questions about the specifications or capabilities of any of the instruments. Please feel free to give us a call at 888-852-5867 and we will be glad to help in any way we can!