#Binocular magnification chart full

#Binocular magnification chart full

They can take full advantage of binoculars that produce an exit pupil of 7mm. Most people younger than 30 who observe under a dark, rural sky will have pupils that dilate to about 7mm. Observers who want the brightest possible images - and who doesn't? - should try to match the exit pupil to the pupil size of their dark-adapted eye. Unfortunately, as we age, our eyes' ability to adapt to changing light levels decreases. As the human eye adapts to darkness, the pupils dilate to let in more light. So, for example, all 10x50 binoculars have an exit pupil of 5mm and 7x50s have exit pupils of about 7mm. You can calculate the exit pupil by dividing the aperture by the magnification. This describes the width of the beam of light as it leaves the eyepiece. Another key specification is the exit pupil. Giant binoculars, those with magnifications above 10x and apertures greater than 50mm, require a tripod to deliver good views. If the magnification exceeds 10x, you likely won't be able to hold the binoculars steady enough to get a sharp image. The highest you'll want for hand-held binoculars is about 10x. For astronomical purposes, go for binoculars that magnify at least 7 times. The first of those numbers refers to the binoculars' magnification.

Binoculars with an aperture of 50mm gather twice as much light through each lens as 35mm binoculars. The second of those numbers refers to the diameter (in millimeters) of each of the front lenses, so 7x35s have a diameter of 35mm and 10x50s have a 50mm diameter. You can find the aperture simply by looking at the two numbers displayed on every binocular: 7x35 or 10x50, for example. Those with apertures of 35mm or less may be great for daytime viewing, but they won't gather enough light to give good views of most objects in the night sky. Astronomical binoculars should have a diameter of at least 40 millimeters (mm). The larger the diameter, the brighter the resulting images.

Aperture describes the diameter of the front lenses. Aperture is the most important binocular specification, at least in those intended for stargazing. Even if the appeal of stargazing eventually wanes, binoculars can be used for more down-to-Earth pursuits.īefore you purchase binoculars, you'll need to understand a few basics. If you're a parent hoping to foster a child's interest in the universe, binoculars are the ticket. Unless you have money to burn on image-stabilized models, binoculars offer a more affordable way to tour the heavens than a telescope. If that still hasn't convinced you, maybe price will. And for most people, observing with two eyes open rather than one seems more natural and comfortable. That portability also makes binoculars ideal for those clear nights in the middle of the week when you don't have the time - or inclination - to get out a telescope. They require no effort or expertise to set up - just sling them around your neck, step outside, and you're ready to go. They have a wide field of view and provide right-side-up images, making objects easy to find.

In many ways, binoculars prove superior to a telescope for those starting out in astronomy. Binoculars are highly versatile instruments that can reveal craters on the Moon, moons orbiting Jupiter, Milky Way starfields, and even other galaxies. Although a telescope may seem the logical choice, there's an alternative that in many respects works better. Ask someone what equipment they need to start exploring the night sky and, 99 times out of 100, they'll fire back 'telescope' as the answer.