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What are binoculars
For those starting out in astronomy. binoculars will prove more useful than a telescope.
They consist of an objective lens (the large lens at the far end of the binocular), the ocular lens (the eyepiece) and a prism (a light reflecting, triangular sectioned block of glass with polished edges).
 The prism folds the light path and allows the body to be far shorter than a telescope. It also flips the image around so it doesn't look upside-down. Specifications
A good size binocular will allow you to see delicate star clusters, bright galaxies, the Moon, planets and nebula.
Astronomy binocular should be 10x50 or above, meaning 10 times magnification and 50mm aperture.
Magnification is determined by the eyepiece (or ocular lens) and, in this example, will make the object appear 10 times closer to you.
Aperture is related to the objective lens (the large lens at the far end of the binocular) and it determines the brightness and clarity of the image you view. As a general rule the higher the magnification the dimmer the image and narrower the field of view, and the larger the aperture the better the image resolution.
A good astronomy binocular will contain a porro prism. This consists of two right-angled prisms joined so as to reflect the light path 3 times.
 10 x 50 Astronomy Binoculars
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Aperture
 40mm is a great mid-range size, and is an entry level aperture that is acceptable for studying the Moon and brighter deep sky objects 50mm+ binoculars are good for most astronomical viewing and will allow brighter images at high magnification in low light situations. They usually weigh 800 grams or more and so you might need some stability support, such as a tripod.
Other Considerations
Zoom binocolars are not recommended for astronomy. Waterproofing is not generally required but can be desirable if you live in an area of high humidity. Shockproof claims for binoculars are over stated as all binoculars are precise optical instruments and should always be treated with care. Recommended Manufacturers
In many cases the brand name is a guide to quality. Companies like Celestron, Leica, Minolta, Nikon, Pentax, Steiner, Swarovski, and Zeiss have earned a reputation for high quality optical products.
Other companies, like Tasco, Jason, and Bushnell have built a reputation on low price.
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Binoculars |
