FAQ Responses

I am interested in buying a telescope. How should I go about making a selection? Buying a telescope, particularly your first one, can seem like a daunting challenge. It needn't be if you remember that buying a telescope is a highly personal thing. There is no perfect telescope. They are all compromises to image quality, portability, light-gathering capacity, cost, and other features. Here’s what I suggest: Talk to a lot of experienced users. Look through a lot of telescopes so you know the differences Have a pretty clear idea of what your primary viewing interests are, and what your budget is. Now that I have convinced you that it’s too much trouble, let me give you the short answer. Aperture, not magnification, is the most important consideration. Aperture is the diameter of the lens or mirror. It determines the amount of light that the telescope can capture, thus determining how faint the objects are that the telescope can reveal. The quality of the optics is probably the second most important consideration. Refractors, the telescope configuration we easily recognize, is generally the best, but most expensive and least portable. Reflectors, which resemble a long stubby tube, are the most common configurations for good quality scopes. If you think you will do primarily planetary and lunar observing, go with a good quality 3” or 4” refractor. If you want something that gives you good all-around viewing of the planets and access to deep sky objects like galaxies, go with the best and largest reflector (Newton, Dobsonian, Schmidt-cassagrain types) you can handle. My best advice is to buy from a knowledgeable source who specializes in astronomical products. That eliminates Walmart, Discovery stores, and your local hobby shop. The Camera Bug and Wolf Camera (14th Street store only) are two local sources who may give you good advice. Shop around, and don’t exclude mail order sources, some of which are on my reference list.   Retailers advertise magnification, I’ve heard others say aperture is more important. Which is correct?   Aperture and magnification are interrelated and play an important part in any telescope choice. Aperture, like photo camera aperture, determines how much light the telescope can capture. This determines how far the telescope can “see“. Distant galaxies require more light gathering aperture, since our eyes are not designed to see very faint objects. Magnification determines how large the object is in the telescope. You can change the magnification by using different eyepieces with the same aperture, although there are limits of magnification for any given aperture. “Seeing“, meaning the condition of the atmosphere... moisture and turbulence, is the most limiting factor affecting magnification. In the moisture-laden southeast, magnification is almost always significantly below the theoretical limit of the telescope. Generally, aperture is considered more important than magnification.     I own a telescope. How should I go about setting it up and using it? The first thing is to set it up in the daytime! Next, read the instruction booklet, and follow along with the instructions in daylight. Working in the dark is a “dumbing-down” experience. What seems simple and straightforward when you can see, becomes a fumbling and confusing experience at night... until you are familiar with your instrument and its procedures. Next, install the finderscope and rough-align it. Choose an object that is easily distinguishable and as distant as you can reasonably make it. A telephone or power line post is good. Choose an insulator or other small feature you can identify in the main scope. If nothing else, choose a distinctive rooftop feature on the furthest house you can see... no, not the windows! When you have it centered in the main scope field of view, position the viewfinder crosshairs on the same feature and “lock down”, with medium tightness, the adjusting screws on the viewfinder. This will require patience and some mental gymnastics since the objects will be oriented differently and will move in different directions when you view them in the main scope and the finderscope. The orientation will be different depending on the kind of scope you have. This exercise is important for another reason. Pointing and finding objects at night will require the same “learned” behavior, since the scope will behave the same way. If your scope is motorized, you will need to turn it off while doing this, otherwise you will be chasing the object as the scope compensates for the earth’s movement in the night sky. If you have done this and thoroughly familiarized yourself with the controls and procedures in the instruction book, you are ready for “first light”... the first time you see sky objects in your telescope. Position a bright star in your rough-aligned viewfinder. Now look in the main scope. Is the star in the center of the main scope? Probably not! Center the object in the main scope. Go back and loosen the viewfinder positioners one at a time just enough so that you can make minor adjustments to center the star in the viewfinder. If you have different eyepieces, start with the lowest magnification and refine the alignment moving to higher magnifications. When the object is centered in the viewfinder and the main scope, you are finished. Tighten down the viewfinder adjusters. The better your alignment, the easier everything else will be!   I own a telescope, but I can’t find anything with it. What’s wrong? First, did you set it up and properly align the finderscope as covered in the previous question? If not, do that before you go on. Start with easy objects. The planets are easy subjects and great fun! Saturn and Jupiter are the best, but they are winter targets. Don’t overlook the moon. It can be a wow!!!!!! experience. These targets will help you get oriented with the images in the finderscope and what you see through the main scope. Work with different magnifications if you have more than one eyepiece. When you are ready for more of a challenge, check out my Calendars sections for good viewing objects in the current month. You will need some aids to help you find more difficult objects. The best one is a planisphere. This handy chart can be purchased at most book stores and specialty stores like Discovery. It gives you a picture of the sky for any month, day, and time showing constellations and major objects. Next, buy an observing book. "Turn Left at Orion" and "The Starry Nights" are two good ones. A more advanced book is "The Year-around Messier Marathon Handbook" by H. C. Pennington. These books give more detailed instructions and diagrams to help you find your way around the sky. Some will show you what the object will look like when you find it. In my opinion, there are three challenges that the beginning observer faces: Things are not what they seem... objects will appear fainter, and without color. Deep sky objects like galaxies are often described as smudges or fuzzies when viewed through small telescopes. The observing skills you acquire with practice will allow you to “see” objects and detail missed by other, less-experienced observers. Distances are deceiving when measuring the sky. The half-inch space between two objects on the planisphere are much greater when applied to the sky. North may still be north on the celestial sphere, but it works differently. Orient the maps and other aides you are using to the position of the constellations. This will help you get the proper orientation. Finding difficult objects and recognizing their unique features is the great reward in observing. It is an acquired skill that requires practice and great patience... like golf, tennis, and many other sports and worthy hobbies.   I can find objects in my telescope, but they don’t look anything like the pictures. What’s wrong with my telescope? Probably nothing! The great shots printed in magazines from Hubble and other sources set up a false expectation for the starting observer. Amateur astronomers with very expensive imaging equipment can approach some of these images. The human eye is a marvelous instrument, but it isn’t designed to see objects billions of miles away in living color! Seeing conditions, the quality and aperture of your telescope, and the level of your observing skills will determine what you will be able to see. Most objects will appear in various hues of gray, blue, and green. Stars and planets will take on stronger hues of red, orange, blue, and yellow.   What does “star-hopping” mean? Observers find an object by identifying a series of stars that lead them to the object, then they “hop” from one star to the next one on the path until they have the object located in their main telescope. This is done by positioning each star in the center of their finderscope, then moving the scope in the proper directions and distances to the next object and so on. Acquiring this skill is the oldest attribute of the veteran amateur observer. The Astronomical League publishes lists at various observing skill-levels. Observers become “Certified” by locating all of the objects on each list.   What does a scope with ‘GoTo’ mean, and should I care? A scope with ‘GoTo’ capability means it will find an object automatically. That is, the user identifies the object by one of its scientific designations, or by supplying its coordinates. The scope (and/or mount) has a built-in computer. It knows where the telescope is pointing and knows what the target coordinates are. It calculates the set of instructions to move the scope to the new coordinates, and sends them to the motor drives on the mount. This is a new innovation in low-end telescopes and is a very “hot” topic. Veteran observers decry its introduction since it negates the skills associated with finding the objects by star-hopping. Would the golfer be happy if a machine did his/her putting... (hmmm, may be a bad analogy...)? On the other hand, it has popularized amateur astronomy by introducing early successes for the beginning observer, and has some very practical uses for the astro-imager.