Getting Started

Binoculars are the key to successful observing in towns


Knowing the stars and the motions of the heavens can be a satisfying and entertaining skill. It can also be useful, since you can determine directions and time from the stars. If you are not already familiar with the night sky, a systematic effort will be necessary to acquire this knowledge. It is best to take a little time every clear night and see what is to be seen, through a year. At the end of the year, you will be surprised at your attainments. Very little equipment is necessary. I recommend that you acqire binoculars, and Norton's 2000.0 Star Atlas and Reference Handbook. This is all that is necessary for years of enjoyment.

I have a very poor observing site, in the city of Denver, with streetlights and houselights on every side, and a good view only to the south. I can block the direct light from the streetlights with trees, but even so only stars down to 3rd magnitude are clearly visible even on a good night. However, when I look through my binoculars, stars of the 6th and 7th magnitudes are visible. At such locations, binoculars are essential for a good experience. It is not so much the magnification of the binoculars that is important, but that they spread the background light over a larger area, while the pointlike stars are not spread, so that the contrast between them is greatly increased. Any binoculars that you can afford will do. It is pleasant to use good binoculars, but even poor ones can allow you to see the stars. It is not wise to begin with a telescope before you are very familiar the sky. You will be totally lost, and the telescope will be of no help in learning the sky. Indeed, a telescope can be a great disappointment, but binoculars will be a joy.

If you live in a rural area, you are extremely fortunate with respect to viewing the sky, and you can easily see things that are almost never seen in the city, such as the Milky Way, and binoculars are not nearly as important.

For the present purposes, cheap binoculars are a great improvement on no binoculars, and expensive binoculars give little more. But make sure that you get real binoculars, with mirrors or prism to erect the image and bring the eyepieces closer together. Opera glasses and suchlike are useless. They are badly made, and have a small field of view. Binoculars designated as 6 x 35 or 7 x 50 -- the first number is the magnification, and the second is the diameter of the objective lenses in millimetres -- are excellent for our purposes. A magnification of 10 or larger is too high: the field of view will be small, and the instrument will be hard to hold steadily. There is also no special benefit in a large objective. More important is a large field of view, and the larger the better.

Look through the binoculars before you buy, and make sure you can move your eye a little and still see the full field of view. When you bring the binoculars to your eyes, you should be able to see immediately, without any adjustment, and with your eyes far enough away from the eyepieces to be comfortable. One eyepiece should be adjustable to take care of differences in refraction of your eyes. You can't wear glasses and use binoculars successfully, since you can't then get your eyes close enough. Adjust the focus to allow for the refraction of your eyes. It is nice to have a focus lock, but this only comes on expensive binoculars.

If you are under 30, your eyes will still have enough accommodation to make focusing a telescope difficult. Adjust the focus as far as possible in the direction for increasing distance, since you will find a considerable range that you can bring to focus. When the binoculars are focused, the stars should look sharp, without rays or other projections. You will notice some deterioration in the images as you bring them to the edge of the field of view. Do not expect too much of inexpensive binoculars in this respect, but most do a remarkably good job.

A tripod is sometimes recommended to hold the binoculars steady. This is necessary for high powers, but it greatly reduces freedom of use. Often, you will be satisfied by holding the binoculars freehand, perhaps resting your elbows on a solid surface, or otherwise bracing yourself.

Use a star chart to find out the real field of view of your binoculars, so you can better estimate distances. Also, find out the dimmest stars you can see easily under different atmospheric conditions. Binoculars will make it possible for you to see Uranus, by the way, which is usually about magnitude 7, and Jupiter's Galilean satellites quite easily. The Moon will show fascinating detail. You will not be able to see Saturn's rings as anything more than a distortion of the image, unfortunately.

For many years, I have used 7 x 35 binoculars with a 10.5° field of view by Sunset, but now I use a Pentax 7 x 50 with a 6.2° field of view. A few years ago, I came across a Miranda 8 x 32 binoculars from Macau, very light and inexpensive, with erecting mirrors instead of prisms, that nevertheless do an excellent job. Edmund Scientific of 101 East Gloucester Pike, Barrington, NJ 08007 offer good-quality 7 x 50 binoculars with a 7° field of view for $89.95 that will be thoroughly satisfactory. All the binoculars mentioned have coated optics, which reduces glare and reflected images.

Not every night will be satisfactory for observation. Clouds, and the moon, are the usual reasons stars will not be visible. Haze and light cloud will scatter enough city light to hide the stars. Dark nights with a clear atmosphere are rarer than you might think. Even here in Denver, good viewing nights are unusual enough that they are worth looking out for. A clear view to the south is best. A view to the north shows the circumpolar stars, and is good for telling the time. If you do not have a view of the western horizon, perhaps there is a park near you with such a view. Alas, in the United States the pervasive danger of crime keeps lights burning, and counsels against parks after dark, especially for individuals.

Reports continue to appear in magazines and newspapers of people who have purchased expensive computer-controlled telescopes to help them find objects, only to be rather disappointed by the results. It seems to take considerable skill to orient the telescope in the first place, and the instruments are not very stable after that. They remark that all stars look alike, which is nearly true, and complain about an inability to see planetary detail. There is not a lot of planetary detail to be seen in a small telescope--there's the moon, bands on Jupiter, and Saturn's rings, all visible with very modest magnification, but just out of reach of binoculars. The computer control is surely a wonder, but it is not really what is wanted. You will have little difficulty finding objects if you are familiar with the constellations, and high magnification is usually a distraction, not a help.


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Composed by J. B. Calvert 1999
Created 17 May 1999
Last revised 29 July 2001