Binoculars allow excellent moon views, and great viewing of star fields, comets and even deep sky objects. They are especially useful for beginners as unlike astronomy telescopes they keep the view the the right way up, making it really easy to navigate the skies. With a little practice you can pick out several of the planets and even the larger moons orbiting Jupiter. Clusters like Pleiades look great because the binoculars wide field of view lets you have more of the cluster in view at one time than a telescope would.

So how to choose which ones? Binoculars have two specifications marked on the body of the binocular in the form of 7x 50, where the first number represents the magnification (in this case 7 times) and the second the aperture in millimeters (50mm in this case). When it comes to selecting the right binoculars for astronomy, aperture is the most important feature to think about. The bigger the aperture the more light is captured so the brighter and clearer the image will be. For astronomy use you will need at least 40mm aperture and preferably larger.

You will need a magnification factor of at least 7, maybe up to 10 if you have a steady hand. Any higher than about 10 times magnification and you will need to mount your binoculars on a tripod as the hand shake effect makes it difficult to get a sharp image.

There are giant binoculars available with higher magnifications and apertures which are designed for astronomy use but you will certainly need a sturdy tripod or mount to use them. These can offer excellent viewing up to about 25 times magnification with 100mm apertures.

This brings us to another point, a specification known as the ‘exit pupil’. This specification refers to the diameter of the shaft of light that exits the eyepieces and into your eyes. You can easily calculate it by dividing the aperture by the magnification so that 7 x 50 binocular has an exit pupil of just over 7mm. Capturing as much of that as possible is good as it means all the available light is getting to where you want it, i.e.your eye. If you are still in your twenties you can probably use all of that 7mm exit pupil mentioned above as your pupils will dilate to about that size in very dark conditions, however as you get older your pupil does not dilate more than about 4 to 5 mm so large exit pupils are wasted (though it starts to make those 25x 100’s look good!).

You might notice another specification marked on the binocular, the field of view (FOV), it refers to the apparent side to side view as you look through the binoculars. It will be expressed as an angle in degrees or a measure such as 340 feet at 1000 yards. For astronomy use we can generally ignore that factor, it really does not matter a great deal at the distances we’ll be viewing at.

So now you have the basics why not get yourself some binoculars and indulge in a little casual astronomy, you’ll be rewarded with some wonderful sights!

theres plenty of cheap binoculars on ebay, are they trustworthy for less then £50? what kind of spec am i looking for? any particular lense colours, prisms, zoom etc am i looking for gazing into the night sky rather then say bird spotting?

for comparison could anybody also tell me what would be the difference in the detail of the moon as seen from both of the above

But now im not sure if these will be sufficient for what I want. I want to be able to view planets with clarity. People have been raving about this telescope http://www.opticsplanet.net/bush-ts-785003.html

They all say its great for beginners, and one reviewer said that the rings of saturn he saw blew him away!

Binoculars would be a lot easier to use because with telescopes it will be troublesome to be dragging whole thing around the house. Please, tell me, which one of these would be best for my needs. I need to stay within the $0-100 price range by the way incase you have any suggestions. Thanks!!!