Astronomy Binoculars Explained

For those starting out in astronomy, binoculars may prove handier than a telescope. For casual astronomical viewing 7x50mm binoculars are good  and will allow brighter, wide field images of numerous astronomical targets. These include delicate star clusters, bright galaxies, the Moon, planets and nebulae.

Binocular Basics

Binoculars consist of a small ocular lens (eyepiece), a larger objective lens (ocular) and a prism, which is a block of glass that acts like a mirror. A 7×50 binocular means it has 7 times magnification and a 50mm diameter aperture to collect light for image clarity. The porro prism, consisting of two right-angled prisms, then reflect the light path 3 times. This allows the body to be far shorter than a telescope. It also flips the image around so it doesn’t look upside-down. 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.

Other Considerations

Astronomy binoculars usually weigh 800 grams or more. So you might need some stability support, such as a tripod. Although generally not required, waterproofing can be desirable if you live in an area of high humidity. Finally, binoculars are precise optical instruments. As such, they should always be treated with care. This is in spite of shockproof claims to the contrary.