Updated 24 Feb 2008
This page will answer some basic questions consumers often have when purchasing (or contemplating the purchase of) a first telescope. I was inspired to put this page together after a conversation with two employees of "The World of Science" store in the Crystal Mall (Waterford, CT USA).
The contents of this page applies to small to medium sized, beginner (or "first") telescopes. By small, I mean 2.4 inch (60mm) to 3 inch (or 75, 80 and 90mm) refractors, and 4.5 to 6 inch (100-150mm) reflectors (6 inch telescopes are generally thought of as "medium" sized). Telescopes in this beginner class typically sell for $150 to $600. Quality starter telescopes are available from a number of manufacturers. The buyer should be aware that there are many very poor quality telescopes in the marketplace; these are most often found in "department stores". It is hoped that the information on this page will help out prospective new astronomers and to advise them not to expect too much from a small telescope. If you have any questions, please send e-mail to Joe Roberts and I'll try to help!
Many amateur astronomers will tell you that the best way to get into astronomy is to first learn some of the basic constellations, and then use a pair of binoculars to find your first "deep sky" objects. It is important to learn the basics of finding your way around the sky (you will need these skills to find objects using a telescope). Binoculars really can show quite a number of interesting sights in the night sky. A good pair of binoculars will often cost less than a telescope; in fact, if your budget only allows spending about $100, you might be better off buying a decent pair of binoculars and a good starter book rather than a telescope. Most experienced amateur astronomers agree that "jumping in" with a fancy telescope without first learning the basics is not the way to get involved. Astronomy is a fascinating hobby but it's not for everyone. If you "jump in" and spend $1000 on a fancy telescope and then later find you're not really into it, you will have wasted a considerable amount of money. Binoculars are a great way to get a taste of what backyard astronomy can offer. Another great way to start in astronomy is to visit a local astronomy club (most cities have some kind of club). Clubs often have loaner scopes, or at minimum, there will be members that will be happy to show you a number of telescopes. Binoculars can be a good first step, but they won't show any detail on the planets (and limited detail on the Moon). If you have a pair now, do try them out.
DON'T EXPECT a small telescope to show images like those you may have seen in magazines. Those pictures are likely from the Hubble Space Telescope or some other large professional telescope. If you are expecting "video game" type images with amazing detail and color, you will likely be in for a letdown.
What can you expect to see? Below we will describe what you might reasonably expect to see with small telescope:
NEW: To gain an idea of what Saturn might look like through a small telescope, check out this article: Simulated Telescope Images.
Many beginners don't realize that a telescope's performance is often at the mercy of ambient local conditions and sky conditions. Other than the obvious (clouds, fog, etc.), there are several other major factors which limit how much can be seen.
First, it is very important to give a telescope a chance to cool down to the outside temperature (especially for Newtonian Reflectors and Schmidt Cassegrain Telescopes). Cooling down of the scope is called thermal stabilization. If a telescope is brought from a warm house out to the cold night, the images seen through it are likely to be very bad at first, perhaps to the point where the telescope won't even seem to focus at all. This is because the optics in the telescope are undergoing a change in size due to the temperature difference. The actual change in the optics is extremely small in human terms; however, at the wavelengths of light, it is very significant. Bottom line: Make sure a telescope has time to cool down to the outside temperature before expecting it to perform at its best. Acceptable performance is usually reached with 15 to 20 minutes, but the very best performance may take one hour or more (depending on the temperature differential and the type of telescope). Storing a telescope in an unheated garage may help to shorten the time it takes to cool; alternatively, set the telescope outside an hour or so before you plan to use it. Keep in mind that even after it has cooled down the images still may not be too good. This is often due to the topic of the next paragraph, seeing conditions.
Second, seeing conditions are very important for good viewing (especially so for the planets and the Moon). When you look at an astronomical target, you are seeing it through the Earth's atmosphere, which essentially is an "ocean of air". Very often the atmosphere is highly unsteady, due to thermal variations, air currents, etc. All of this means that an image passing though it will be distorted to some degree. Have you ever looked over a toaster while toasting some bread? The image of objects behind the toaster seems to shimmer. Now, imagine looking through miles of turbulent air at high magnification! In short, bad seeing conditions can severely limit the amount of fine detail you can see (fortunately bad seeing has much less effect on galaxies, star clusters and nebulae). Seeing conditions are often a function of where you live. Areas like Froida are known for good seeing. On the down side, nights of "truly" good seeing are fairly rare here in New England. You may have to observe for a dozen nights before you happen to get a night where the air is very steady!
The third major (and rapidly growing) problem facing astronomers is light pollution, a problem that is unknown to most non-astronomers. Light Pollution has (for all practical purposes) completely ruined the skies of just about any moderate to large city (this means that the only things you'll be able to see are the Moon and bright planets). Light pollution is caused by excessive amounts of and/or poorly designed outdoor lights. Light pollution will not affect the viewing of the Moon and planets, but it can seriously limit the number of non-solar system objects you might otherwise see (objects such as galaxies, star clusters and nebulae). Light pollution has invaded almost all populated areas of the country. Often, the only remedy is to drive to a dark location, generally 50 to 100 miles or so from any major city (and even at this distance some evidence of light pollution may be quite visible). For more information on light pollution, see my article dedicated to this topic: Light Pollution. For a very comprehensive treatment of light pollution, see the International Dark Sky Organization's web site at www.darksky.org.
Most beginning astronomers think that high magnification is they key to great viewing. This is a common misconception. Any experienced amateur astronomer will tell you that most observing is performed using low magnification. For small telescopes, low magnification (or "power") means anywhere from about 20x to about 50x. High power is useful (and often necessary) for viewing planets and double stars. However, initially finding a planet (or any object) is much easier with low power. Even users of large telescopes use mostly low power. The most magnification that is useful in a typical small telescope is in the range of 100x to 200x (for 'scopes in the 6" range). Small telescopes do not gather enough light for satisfactory high power views of galaxies and nebulae. So, resist the temptation to "go to high power"! Stay with low magnification for most objects, and you will see much more!
Getting quality images in a reflecting (Newtonian) type telescope is very much a function of the alignment or collimation of the optics (misalignment is common among reflecting telescopes but almost never an issue with refracting telescopes). If the optics are out of alignment, you will still "see" through the telescope, but very likely the images won't focus properly, or the image will seem very distorted. Most telescope manuals provide instructions on how to collimate the optics. It can be a bit tricky; do the initial alignment indoors (fine tuning can be done outside at night). Collimation tools are also available for around $40 and are a great help in aligning the optics. Optics do need to be checked for alignment from time to time, especially if the telescope has taken a bumpy ride in the back of a car (for example). If you want to eliminate the "maintenance" associated with telescopes, buy a refracting telescope.
As far as beginner telescopes are concerned, there are many "junk" telescopes out there, and then there are some decent starter scopes which are not too expensive. Expect to pay at least $200 - $500 for a quality beginner telescope. You can find scopes for around $100, but beware. They often make claims that are preposterous, and are of very poor mechanical and optical quality. You are better off buying a simple (but well made) telescope. In other words, buy a telescope where the money has gone into basic functionality (good optics and a good mount). "Junk" telescopes are easily identified, since they come "standard" with numerous (but often useless) accessories!
Of paramount importance in any telescope is optical quality. While a beginner telescope cannot offer "custom hand made and certified state of the art optics", ones from reputable manufacturers are generally quite satisfactory. It is generally best to avoid "department store" telescopes. Some of them have a satisfactory main optic, but most of the time the eyepieces (discussed below) are of marginal quality. The very worst telescopes have plastic lenses... needless to say, these units will have extremely poor performance.
Perhaps the second most important part of a telescope is its mount. There are numerous types of mounts (beyond the scope of this article). They key is to make sure the one that comes with the scope you're considering is smooth, stable, and solid. Few things in Astronomy are more frustrating that fighting with a poor telescope mounting in the dark! Poor mountings will make using high magnification especially annoying and frustrating. Purchase a telescope with a simple (but quality) mount rather than a cheaply made "advanced" mount!
One of the important items that come with a telescope are the eyepieces. The eyepieces allow you to change the magnification of the telescope. Many "trash" telescopes provide 3 or 4 virtually worthless eyepieces (many of which result in a magnification well beyond the useful capability of the scope). For small beginner telescopes, it is much better to have one or two quality eyepieces (as opposed to a battery of junk eyepieces). One eyepiece that produces low magnification (say 30x or so) and one for high magnification (about 100x) is the best bet for a beginner. Eyepieces are marked with letters and numbers; these characters denote the optical design of the eyepiece and the focal length of the eyepiece. Beware of telescopes that have eyepieces with any or all of the following markings: H25, H20, H12.5, and SR4. If the scope has one or more of these eyepieces, it is likely that the images will be marginal to poor. The "H" stands for "Huygens", one of the poorest performing optical designs ever made (they are inexpensive to manufacture however). "SR" stands for Symmetric Ramsden. Trust me on this: no small telescope will benefit from an SR4 eyepiece. The manufacturer simply includes this so that the high end magnification of the telescope sounds very impressive (it is a marketing ploy) Most people will find using an SR4mm eyepiece extremely frustrating. The SR4mm eyepiece has what is known as very poor eye relief. If you wear glasses, the SR4mm eyepiece will be impossible to look through. Eyepieces with poor eye relief require that your eye be very close to them, often uncomfortably close even for those with normal vision. The bottom line: Any telescope will have sharper and brighter images when LOW magnification is used. And, finding objects will be MUCH easier!
In the beginner telescope market, this question has become clouded in recent years. Meade and Celestron are two major manufacturers of telescopes; in years gone by all the telescopes offered by these companies were good to excellent. Not so today; the name Meade or Celestron on a telescope no longer guarantees that the scope is a good one. Meade and Celestron have made a much bigger presence in the "consumer" telescope market in the past few years. In the 1970's, if you owned a Celestron telescope, you owned a good telescope (period). Back then, all of their telescopes (about 4 models) were American made. Today, both Meade and Celestron have entered into the low end telescope market, and both companies tend to "distance" themselves from admitting this fact. Both Meade and Celestron still make some outstanding products; the problem is, the good ones are found less and less frequently in consumer outlets. Meade has been marketing telescopes under the "Saturn" brand; these scopes are ones that are "jazzed up" with lots of trashy accessories and a very eye catching package (no doubt to lure parents into purchasing the units). If you want a REAL telescope, my advice is to avoid these telescopes. Another confusing factor is that many of the model numbers of these "consumer" versions of telescopes are very similar to the "real" telescope. For example, Meade used to make a nice starter telescope, a 4.5" Newtonian reflector, model number 4500. I have seen "consumer" versions of this scope with very similar model numbers (like 4501, 4500E, etc). These versions of the scope provide 3 lousy eyepieces, a worthless Barlow lens, a less stable mounting, a smaller and cheaper finderscope, etc. The whole scope is a significantly inferior version of the "real" scope.
So, what does all this mean? Meade and Celestron still do make some very nice starter telescopes, the key it to get one of the "real" scopes. Orion Telescope and Binocular also offers a number of very nice starter scopes. If you are not sure about a telescope model, e-mail me and I'll try to help.
There are several types of computerized telescopes. One type, often called "GOTO", will find objects for you automatically (more on this below). A second type is called "push to". These scopes help you find objects, but you must actually make the scope move.
As stated, a "GOTO" telescope is a scope that can find things for you. After an initial alignment, you punch in the name of an object (usually through a hand held control) and the scope will go and find it for you. Do they work? Sometimes... but that statement comes with a number of qualifications. A number of the beginner go to telescopes in the market have had problems quality control (although reportedly this has improved in the last few years). I know people that have had to send such scopes back to the manufacturer several times. Some other points concerning GOTO scopes: (1) it costs money to add this feature; on a beginner scope (in my opinion) the money available should go into the optics as compared to electronic gadgetry. (2) Many GOTO scopes have libraries containing "tens of thousands of objects". The problem is (especially in the light polluted environment that most users will be in) that the vast majority of these objects are far too faint to be seen in a small telescope. In reality, the number of objects that will be visible (and interesting to a beginner) is probably less than 100 (one hundred).
Personally, I am not a fan of low priced GOTO telescopes. From my observations, the ones that are available in the low priced market have shown a number of quality control problems (although reports are that they have improved). I recently tried to help a person at a star party who had an entry level go to scope (Meade). I was not terribly impressed with the scope's ability to locate objects. Despite a careful alignment the scope could not place objects into the low power field of view (it was not too far off but for each object tried some manual button pushing was needed to get the object into the field of view). The higher end scopes (Meade's LX200 series) do have GO TO capability that does work well, however these scopes are over $1000 typically.
I grew up in the "old school" of amateur astronomy, that is, I learned the sky and learned to "star hop" to objects I wanted to observe. A higher end GOTO telescope does have some remarkable capabilities however. It can allow you to locate a number of objects in a short time. However, there is a drawback. While a GOTO scope can locate objects for you, it denies you the opportunity to learn your way around the sky. A GOTO scope is kind of like a car that takes you to any address you specify, but with no knowledge (or view along the way) of how to get there. With the star hop method, you learn to recognize star patterns and often you see interesting things along the way. While I am not a fan of GOTO scopes, I do recognize that some people do like them a lot, and for some applications they can be quite helpful. For example, if you have light polluted skies, it may be hard to use the "star hop" method of locating objects because there are not many stars that can be seen (necessary for star hopping). A GOTO scope will find things for you even if there are few stars visible to the naked eye. However, if your skies are particularly poor, don't expect to see much through the main scope either. Another thing about GOTO scopes: there is more stuff to act up and break down. A simple scope with a basic mounting is for all practical purposes a lifetime instrument, there are few if any parts that will ever wear out or stop working. Sooner or later (due to the sophisticated electronics, gears, motors, etc), most GOTO scopes will likely develop some kind of problem. So, I tend to not recommend scopes with GO TO features, however that is my personal opinion.
There are a number of places to buy a telescope... however I advise against purchasing a telescope at a department store! There are only a few "mall" stores that I am aware of that sell quality telescopes: The Nature Company, The World of Science and The Discovery Channel Store. These outlets are found in larger malls around the country. Keep in mind however that not all of the scopes sold by these outlets are what I consider "good". Typically, there will be several telescope models to choose from, most in the $100 - $300 range. Often, these outlets will have a Meade ETX and/or Meade LX200 scope nearby, costing about $600 and $2000 respectively. There's a reason these scopes cost a lot more than most of the models... they are good scopes!. Wal Mart often has a number of telescopes (especially around the holidays), however all of the ones I have seen there are not ones I would recommend.
Perhaps the best place to purchase a telescope is through mail order. The best way to see what's available via mail order is to pick up a copy of Sky and Telescope or Astronomy magazine. Both are loaded with mail order ads from many companies and distributors. A great deal more selection is available via mail order than through any other source. The downside is that you can't check out the 'scope firsthand, you'll have to wait for it.
The following is a list of mail order outfits I have personally dealt with, and recommend without hesitation (please note that there are many more I have not dealt with that are probably just as good!):
I strongly recommend avoiding Tasco telescopes. I suggest avoiding the so called "New York Camera Stores" (or similar stores in other big cities) if possible; the people that work at these places generally do not know what they are talking about when it comes to telescopes (and service is less likely to be personal). Also, stay away from telescopes sold at "Brookstone", "Radio Shack", and most "chain" type camera stores. Again, look for the classic sign of a low end telescope: eyepieces marked H25, H20, H12.5, and/or SR4 along with a long list of accessories and a fancy box covered with pictures (which were probably taken by a large professional telescope). If you see any of these, I recommend that you look elsewhere! Some of the very best telescopes arrive in plain old brown cardboard boxes.
As mentioned at the beginning of this article, it's best to first learn the constellations and to have sampled the skies using a pair of binoculars. If you've done this and you have a thirst for more, you are ready to move up to a telescope. In my opinion, $500 is probably the least you can spend to get a truly decent starter scope and the necessary accessories you'll need to round out the package. Most astronomers will tell you to buy the biggest scope you can afford, and I generally agree with this statement. With a $500 budget, my personal recommendation for a starter package would include a 6" Dobsonian reflector telescope. A 6" scope is big enough to show good detail on numerous objects, and yet is quite portable. A 6" Dobsonian scope (like the ones Meade and Orion sell) will eat up about $350 of your budget (including shipping costs). The remaining $150 should be used to purchase another good quality eyepiece (about $50 - $70) (assuming that the scope only came with one eyepiece), and a good book (I'd suggest "Nightwatch" by Terrence Dickinson, avilable at most decent bookstores). Any remaining funds could be used towards a subscription to Sky and Telescope or Astronomy, two great magazines dedicated to amateur astronomers. If you've got an extra $100 or so to add to your budget, you can move up to an 8" Dobsonian reflector, a very capable telescope that could even be with you for a lifetime of observing. Sometimes you can find deals on scopes for even less money. EBay is another source for telescopes, but you are at some risk (you have no assurance that the scope is not damaged, etc). Every once in a while you can find a nice scope at a tag sale, but you need to know enough about the unit to decide whether it is worth the cost. People who have good scopes know what they have, and they will not show up for $25 at a tag sale! As mentioned previously, local astronomy clubs might be your best option to get introduced to a telescope. You may be able to get a loaner scope from a club, one that might cost a lot more than you might want to spend. Also, should you find you are not into astronomy, you can always turn the scope back in and no money is lost.
It is important to keep in mind that small (and even large) telescopes will not provide visual images like those seen in books and magazines (the Moon is a possible exception). For many objects, you must take satisfaction in just knowing that you have barely detected a faint smudge of light! Only a few of the brightest objects will be considered impressive by the average person. If you go into astronomy expecting brilliant, color filled views of objects in the sky, you will likely be disappointed. Amateur astronomy is not about dazzling "video game" graphics and Hollywood special effects. Amateur astronomy is not unlike learning to appreciate fine art; you must learn to appreciate what you see in your telescope, which in many cases will only be a very faint patch of light (and this may occur while freezing your butt off or by being bit by a swarm of mosquitoes). Even though you might be only able to just barely glimpse a faint galaxy, know that you are seeing an incomprehensibly small portion of the light generated by a billion suns, light which has traveled a journey of humanly unimaginable distance, a journey lasting many millions of years! When you look at a distant planet in a telescope, you are seeing the real thing, live, and you can be sure that only an extremely small fraction of people on Earth are looking at the same object at the same time! You will not be able to see anything close to the American Flag on the moon. However, you can look at these distant objects like the Moon, the planets and galaxies, knowing that you (nor anyone else) will likely never visit them in person, and wonder what it might be like if you could actually personally visit them. You also know that these objects are countless times older than any person alive, and that they will still be there long, long after Mankind has ceased to exist on Earth.
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