Helpful Hints For Using Your New Telescope

What Can I See?

Look at the moon first if it's up—it has terrific detail! As long as it's not completely full, there will be a line between the lit and shadowed parts. You can see the most detail along that line: craters, mountain ranges, smooth lava flows, and more. Nothing man-made can be seen at this distance though.

Planets aren't always up, but some are well worth finding. The planet Jupiter has four large moons that are in different positions every night. You can also see bands of clouds in its atmosphere. The rings of Saturn are easy to see in any telescope. You can often see a thin, dark gap between two lighter rings called the Cassini Division, and the shadow cast on the rings by Saturn itself. Mercury and Venus show phases like the moon. The other planets rarely offer much detail, but you can see all except Pluto with any scope. (Pluto requires a telescope at least ten inches in diameter.)

Your telescope can also show you beautiful star clusters, clouds of gas and dust, remnants of exploded stars, binary stars which are slowly orbiting each other, distant galaxies, and more. However, nothing in the telescope is going to look just like the photographs you see in magazines or on the Internet. Cameras can build up a picture over several minutes, while your eyes only save information for a fraction of a second. However, your eyes can see dim and bright areas at the same time, while a camera often has to overexpose the bright center of a galaxy or nebula to show the fainter, outer regions at all. The telescope shows you a more delicate, translucent image without bright colors, but many people consider that to be the more pleasing view. Besides, it's real!

The planets and the moon are the only bodies that you can see well through city lights. Everything else is going to be washed out. To see any detail in galaxies or nebulae, you have to take your telescope to a dark location. (Don't go when the moon is up; it's as bright as city lights.) It takes about half an hour for your eyes to completely adapt to the dark, so be careful not to look at any bright light or you will have to start all over again. Red light is the easiest on your eyes, so take a dim, red-filtered flashlight with you to read star charts.

Your telescope needs time to adapt too. As the air gets cold, warmer air will continue rising off the mirror or lens for a while. That air will distort the light coming through it causing everything to be a bit blurry. The atmosphere often causes this same problem, but there is no need to add to it with a warm telescope. It will take at least half an hour for the telescope to equalize—longer for large reflectors.

If you are having trouble seeing anything clearly, make sure the focus is adjusted for your eyes. If stars and planets look like doughnuts, you are far out of focus.

Viewing Tips

Galaxies, star clusters, and nebulae are faint, but there is a trick for seeing them better. There are two kinds of light-sensing cells in your eyes. Cone cells have sharp, color vision, but need bright light to work. Rod cells can't see color, but work fine in dim light. Cones are concentrated in the center of your eye, and rods are mostly around the sides. This means that to see dim objects, you should use the side of your eye. You can look right at some star clusters and see only a blur, but if you look next to them, you see all the individual stars! Looking next to a galaxy can bring out the spiral arms. This technique is called "averted vision", and it becomes second nature.

The best news about galaxies and nebulae is that you get much better at seeing them. Your brain is used to ignoring faint signals, but as you stare through a telescope at dim objects, your brain starts using every bit of light that your eyes take in. After a few months, you can easily see details that were invisible before. It doesn't sound possible, but it's true!

Finding Things

There are two main types of finders. The simplest one to use is a reflex site like a Telrad or QuikFinder. They work like heads-up displays—you look through a window and see a bull's eye target projected on the sky. The target shows you where your scope is aimed. After you aim, look through your lowest power eyepiece. If you don't see anything, move the scope around a bit to see if you just missed. Don't worry if it takes a few tries—it gets easier.

The most common type of finder is a small telescope with cross hairs etched inside mounted on the main scope. A finder scope only magnifies a few times, so it shows you a larger section of the sky than the higher-power, main telescope. Using a finder scope takes some practice. First, keep both eyes open while looking through it so you see the real sky and the view through the finder at the same time. Ignore everything except the cross hairs against the real sky, and use them to get the scope in the right area. Now look just through the finder. If there is something visible (a small, fuzzy spot probably), center the cross hairs on it. If you can't see anything, use a low-power eyepiece as described above.

Neither finder will work unless you align it first. Fortunately, it's easy! First, find something in the telescope, then, without moving the scope, move the adjustment screws on the finder so that it points at same object. Check the view through the scope again to make sure it's still centered, and that's it! You can do this during the day or night. At night, it's best to use the North Star or something near it because those stars move the slowest. If you do it during the day, your target won't be as far away as the stars. This will affect the alignment slightly, so you will probably need to fine tune it at night.

None of this does any good until you know where to look. Most deep-sky objects like galaxies and star clusters can't be seen at all without a telescope. You will usually be aiming at what looks like an empty spot in the sky! A star chart or computer program will show you these spots in relation to the constellations, but if you don't know any of those, you will have to get a book to help you learn. The best targets to start with are the 109 Messier [MESS-ee-ay] objects. They are named after an 18th century French astronomer, and include most of the best and brightest things in the sky.

Magnification (Power)

Objects in the sky come in many sizes, so you need several eyepieces to give you different magnifications. The most useful powers are from about 40x to 200x. In general, nearby star clusters and nebulae look best at low power, medium is for galaxies and smaller star clusters, and high power is best for planets. You will also want a low power eyepiece to help you find the smaller objects so you can zoom in on them.

The reason you don't really need a power much above 200x is that you rarely get to use it. Shifting air masses of different temperatures cause distortion on any night, and it gets worse as the magnification gets higher. Although it does happen, it is a rare night that allows you to use power up into the 300's and still see clearly.

The magnification is caused by the eyepiece. To calculate the magnification given by a particular eyepiece, divide the focal length of the telescope (in millimeters) by the focal length of the eyepiece (which will also be in millimeters). If the focal length of the telescope is not marked on the side, you can measure the length of the tube and get close enough. The focal length of the eyepiece will be marked on the side, and typically ranges from 4mm to 40mm. Remember, larger numbers give you lower powers.

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