| Things you should know before buying a Telescope |
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The Department Store Telescope. The "Bane" of Astronomy. Sears, Target, Wal-Mart, Pennys' and so on. These places always give me a bad taste in my mouth concerning telescope sales. These are the places where the cheap manufacturers of telescopes distribute their wares. These are also the places where people who are looking for gifts or "shortcut cost" buy telescopes. Because of the prices and the outrageous advertisement of "super" powers on the boxes, they fall for buying them. I don't really blame the stores too much; they just want to make a buck, however the makers of these cheapo scopes mislead consumers. This has been going on for years with no let-up in sight. There isn't much people can do to change anything except help the folks that we can reach. To change how stores sell cheapo scopes is a futile endeavor and meanwhile we watch and cringe every time we see someone buying them thinking they got a hell of a deal and a great gift. The best place to buy telescopes is either from a telescope store that sell reputable names in telescopes or mail-order. Department store scopes in general are garbage. Plain and simple. When buyers or receivers of such junk realize that they have junk, their passion for the hobby is quite dead from frustration. Costco does sell some Meade products like the DS-114. These scopes are one level above junk, so therefore they are usable and upgradeable. If you bought a scope with the name Galileo, Simmons' or Tasco, you might want to rethink the purchase. If you received it as a gift, you could try to enhance it to suitable a performance. The bottom line is this...don't buy from department stores. Use a reputable dealer or mail-order warehouse and do your research. This is important, it's like buying a car, never rush into things. Go to astronomy sites on the web and and ask questions. You won't be sorry. Down below I have included some forums and informative sites to go to.
What you really want and what to expect. Many beginners that begin the search for telescopes will be bombarded with many choices and types of telescopes. Granted, telescopes basically do the same thing and that is to view the cosmos in any way, shape or form. But the questions remains: Which one? How much? How big? Which type? Never ending list goes on and on. You need to really sit down and think what you will expect and do with a telescope once you have it. What is the potential of such telescopes and will it be adequate enough for whatever you desire. Some beginners that do not understand how telescopes work will buy any ole' telescope and try to do astrophotography and then finding out that the equipment they have isn't adequate enough to do the job, therefore they feel "cheated" or even stupid. The most common reason is to just look at the moon and planets and maybe a few other objects. If that is the reason, then your options are a little easier. If you expect to do astrophotography or do sky tracking or comet hunting, then your options are broader. You have to ask yourself what you really want in a telescope and which one would be the right one before you buy anything. Since you would be committed in spending hundreds or even thousands of dollars in equipment you really want to do the right thing. Other factors that come up are weight, storage, maintenance, portability, customer support and so on. The one thing to expect (and this is common sense) is that you get what you pay for. The more you pay, the better (in theory) the scope. The average cost of a decent scope depends on where you buy the scope and from whom. How big is too big? We see pictures of telescopes in magazines and catalogs and in doing so we cannot get a true perspective of their sizes unless we are standing right beside the scope itself. Many people I know are very surprised at how large the scope is when they open the box. Depending on the aperture of the scope basically dictates the size. Remember, telescopes are built "around" the objective mirror or lens. Focal length also will determine length overall. Weight is also a factor to consider; especially if you have a bad back like myself. My CR-150 (6") refractor weighs with all the goodies, 56lbs. The tube itself weighs 20lbs. The other type scope which is bigger than most folks think are the SCT's. You have seen them in catalogs and such and they seem compact. They are, however they can be massive. A Meade 10" LX200 with all the trimming is huge when you're standing next to it. There is alot of work involved when putting together and breaking down these scopes. The smaller version like a LX10 or G-8 are a little smaller and easier to handle overall. Newtonians, either a Dobs or EQ mount can also be large. Remember, the bigger the focal ratio the longer the tube. Example: A homemade 10" f/7 Dobs will have a 70" tube! Which is 2" shy of 6 feet! This will give you an idea what you are up against concerning sizes. Truss Dobs scopes are very large, so think "ladders". I have been to star parties where these "monsters" are over 10 feet long. Always consider the size you are comfortable with and how you will store it. Sometimes economics dictates the aperture for you and usually that means a standard size scope. The average aperture people have is 6" to 8" on reflectors and 3" to 6" on refractors. Something to think upon. Refractor or Reflector? This subject is decided upon either economy or desires or even both. In my experiences, reflectors are the most common for deep sky. This also includes SCT's. Reflectors are mirrors and therefore collimation (alignment) and cleaning maintenance is required regularly. SCT's have a corrector plate or "floating" focuser. The SCT has internal moving parts, so maintenance and "problems" can arise which would entail more "headache". Reflectors can be large, but the bigger aperture you have the deeper in space you can go. People who have the desire to gaze at deep sky goodies, should consider a reflector or SCT. Dobsonians are the most common, but tracking and astrophotography are almost (but not quite) impossible. Strictly viewing. SCT's on the other hand are. The refractor which has less maintenance is not considered a deep-sky scope. Though it can be done to a point, refractors are best at lunar, planetary and guided astrophotography. There are two types of refractors. Achromatic (2 element, doublet) which will produce false color on bright objects such as the moon and planets. Certain quality achromats do very well in the definition of moon and planetary viewing if you can bypass the color diffraction. Most people ignore this and carry on without too much complaint. The other is Apochromatic (3 to 4 elements). These scopes are very expensive due to the work involved in making the lenses. These scopes have a color corrected lens or lenses that are desirable for true color. The Schmidt-Cassegrain (SCT) what exactly is it? For further explanations of this type scope go to the Characterizations section. The SCT is becoming quite popular and well excepted in the beginner scope department. I will not elaborate the design here (go to the link above) but I will say this...they're good. Prices of some of these scopes are coming down, however the better ones are going up. That's America you know. But as for a beginner type scope in my opinion, they can be a handful. Just a reminder. Research this subject if you are interested in this type. Personally this can be a good beginner scope for adults, but I wouldn't recommend these for kids at the beginning. Equatorial, Schmidt-Cassegrain or Dobsonian mounts? Which one? Each one of these has their specific purpose. On occasion, for economic reasons (skinny wallets most of the time) we opt for different mounts than we would like to have. With Dobsonian scopes, they are actually named, not for the scope (which is Newtonian) but for the simplicity of its' design is Alt-Azimuth. Up, down; left right and so on. This type is very simple and no-nonsense. It's there to just hold up the Optical Tube only. Certain other scopes such as refractors come with alt-azimuth mounts also. With these type mounts you cannot track the sky or really do any serious astrophotography except perhaps the moon. These are inexpensive and becoming quite common. The equatorial mount or EQ is designed for tracking, locating and astrophotography. It's main purpose is to align the Right Ascension (RA) axis to the Earths' polar axis. By aligning with the North Celestial Pole (NCP), even roughly, you are able to follow the sidereal rate (sky movement speed) for a long period of time. There are things to be aware of concerning EQ mounts such as stability of the tripod, backlash of the mechanism itself and proper polar alignment. On refractors, EQ mounts are desirable, however on Newtonian type scopes, you may find your focuser pointing at an angle where it is uncomfortable. Newtonian reflectors on EQ mounts are becoming something of the past. Not very many companies are going that route anymore. Mostly common for the smaller reflectors such as a 4.5" (114mm) apertures. The Schmidt-Cassegrain scopes or commonly known as, SCT's, use a fork mount. Almost all SCT's use a fork mount except for perhaps a Celestron G-8 and some of the smaller LX10 Meade scopes. The fork mounted scope is basically an alt-azimuth design except they usually are equipped with a motor drive. Both axis move in unison to follow the sky. There is another option with fork mounts and that is a wedge. A wedge sits on the mount and has latitude adjustments to raise the altitude to your local latitude coordinate. Then by doing this you can use the OTA itself as a polar scope with proper accessories. The drawbacks with wedges is that viewing anything within a 10° or 15° radius of NCP may be extremely impossible because the eyepiece is between the OTA and the top of the wedge. That is why most folks opt for the RA/DEC drivers. This type mount is considered "goto" when computers run the drive system. This will be explained in better detail later. Aperture vs. Magnification. As I have said before somewhere on this site, junk scopes that profess 650x power are down-right liars. The real truth is this: "APERTURE RULES"! Period. Magnification is not really a factor concerning the true power of the telescope and that is light gathering abilities. The bigger the lens or mirror, the better. The general rule of thumb is 50x per inch of aperture. Example: an 6" f/8 refractor maximum allowable (usable) is about 300x, where as a 60mm (2.4") is about 120x...not 650x...big difference. See where people are being mislead. Damn shame. If you are able to get a clear view of something and is bright enough, then the eyepiece (if decent) will clearly show you what it is. If you try to use a 4mm with a 3x barlow, you will see what I mean by stretching the limits. When deciding to buy a scope, regardless of what you can afford, try to get as large as possible aperture you feasibly can. This will allow you to see as much sky as the scope will allow. Don't rob yourself of enjoyment if it is in your power to get light gathering power. Focal Ratio. Without getting too much into the science of focal ratio or focal length, I will just explain the basic nature of what it means. Basically focal ratio is how light is gathered and "presented" to the eyeball. You may have heard of fast and slow focus when discussing focal ratios and such. The smaller the number, the faster the focus and larger the number the slower the focus. F/4.5 is considered fast, whereas an F/10 is considered slow. In a nutshell, the slower the focus, the better the light (color) spectrum. The slower focus is "dim" in a way that in photography it takes longer to expose. The fast focus is "bright" where in photography exposure is quicker. This is a common thing to know in camera lens equipment. The refractor which incorporates a lens is better suited for longer focal ratios. 3.5" (90mm) at f/10 or longer is better suited for planetary use because of the "alignment" of color spectrums. At f/5, it is faster. These type focal ratios that are quite fast are considered "rich field" and are better used with wide fields of view. These fast focus telescopes aren't the best when it comes to planets, however, they aren't too bad for deep sky objects. Some people just do planetary and lunar observing. In this type scenario, having a longer focal length or slower focus is desirable, whereas deepsky observers opt for a faster focus. Usually manufacturer's make Newtonians with a medium to fast focus because of size limitation and what is convenient. A good example is a 8" f/6; the focal length is only 48" long, so therefore making a semi-compact and light scope is done. A 8" f/4.5 is around 36", so the scope will be a shorter version but with a fast focus. That can be desirable if you intend astrophotography. Now, let's say you have a 10" scope. 80% of the time these scopes have a fast focus (majority are f/4.5). Why? Because of size considerations. Example: A 10" f/7 (medium focus) would have a OTA of 70"! That's almost 6 feet long. Very cumbersome, not to mention the tube diameter at around 12". The SCT uses "folded" optics. This enables the use of a large diameter mirror at a longer focal length. An SCT with a 10" mirror at f/10 is only about 2.5" long. The focus is "folded" by the use of mirrors and a corrector lens. What about "GOTO" telescopes? Goto scopes (computerized locater) are fast becoming popular. Because of the fact that once set up, you just push a button or enter the coordinates and the telescope will point at that object. There are a couple of kinds of goto's that are out on the market today. Some of the larger companies (i.e. Meade, Celestron) have a new line of small scope goto's. These scopes do work to a point, however you must understand that these scopes are cheaper in construction and have small apertures. I have encountered a few people that have had problems with these scopes concerning their mechanisms. There are places to check on these scopes by certain review websites. The goto scopes are desirable to beginners because of the "gizmos" that come with them. By just setting it up outside then following the instructions (hope you have good ones) for setup of the alignment and tracking all you do is enter either a number or a series of numbers and the scope will point to that particular object. Now in theory this works, however with the smaller scopes, the computer guiding system accuracy isn't all that great and if it does find the object; with the smaller objective scopes, you may not see it anyway. Advertisements will tell you that the scope has a large object data base, but what they don't mention is the apertures limiting magnitude. This too is misleading. Now not all goto scopes are like that. The larger Meade/Celestron SCT's have built in computerized tracking and in many cases they are considered gotos'. The Meade LX200 (very popular, but expensive) can come with decent tracking and a hefty data base of objects. Shopping around and asking questions will help you decide what is best for you. The downside to goto scopes in my opinion is that it takes away something of the hobby. Goto scopes takes away the ability of learning the sky properly and the ability to "star-hop". I always suggest to beginners to get a scope that will enable them to "hunt". This ensures that you can and will have to learn the sky. Of course it's that very reason that people buy goto telescopes. They seem to think learning the sky will take too long or they are down right lazy to learn if they have a computer to do it for them. Too sad. My suggestion is this. Get a typical telescope and learn the sky...then buy a goto scope later. This will give you the edge if your goto quits working. As for us folks that aren't as young as we used to be, sometimes a goto is ideal; especially if our eyes are going bad or our backs and necks are "wearing" out. There is always a place and time for either goto or non-gotos'. It's knowing when the "right" time is. Digital Setting Circles or DSC. DSC is fast becoming a nice tool. Not exactly goto, but close. These gizmos are specifically designed (depending on your equipment) to sense movement or measure rotation of your specific mount. They work both on Equatorial and Dobsonian Alt-Azimuth mounts. However, not all DSC's can work on everything at once. Some are made for Dob mounts and others for EQ mounts. Once these DSC's are hooked up and calibrated or aligned with a few stars, you no longer need to depend on your mechanical setting circles. Having a chart with printed coordinates is basically required. Just turn the scope to the coordinates by looking at the digital display until you are on target. Pretty simple really. I myself am contemplating in getting one for my CG-5 only to speed up the process during cold and dewy nights. Many people are getting into these gizmos' because of the convenience and time savings. If by chance you are interested in one of these, always check and make sure you can get one for your specific mount or setup. They have become quite pricey, so don't get sticker shock. What about RA/DEC motors and tracking devices? Most of the time when new scopes are bought and if they are EQ mounted, you usually have the option for RA/DEC motors. Granted, these are convenient and downright necessary if you like astrophotography. Getting the right kind for any particular mount you have isn't too hard to do. Most companies or telescope stores will sell optional equipment for the rig you want. Orion Telescopes & Binoculars has an assortment of EQ mounts and motors for each kind. It has been my experience concerning drives is that you really only need one and that is the RA motor. Reason being is that if you are just gazing or doing astrophotography, RA is all you need. Polar alignment is something you also need to learn for the RA drive to work properly. There is another type drive system is encoders (See Digital Setting Circles). Encoders are used for ordinary drive systems that have no "database" of their own. Encoders utilize both RA and DEC to point to a particular object. In a way, this turns your scope into a goto. To me, this is the only few reasons I would use a DEC motor. Bottom line is this: Ask yourself "Do I really need a drive system?". If you are not going to do astrophotography and you're well acquainted with the sky, then perhaps a drive isn't needed. If you are going to do astrophotography then a RA drive motor is all you need. If you want to make your scope a "goto" with an encoder, then both RA and DEC will be required. Last note; drives and controllers sometimes come separately, so pay attention to detail when shopping, and try to get at least a standard quality drive system. Eyepieces? Which ones? When you buy a telescope chances are they will come with at least one eyepiece, but most of the time it will be two. They come in 3 type sizes; .965", 1.25" and 2". 9 times out of 10 you will want to upgrade your eyepiece collection to something better. This is usually recommended by seasoned amateurs and pros' alike. There are five basic type eyepieces. Kellner, Orthoscopic, Plossl, Erfle, and Ultrascopic or Ultra-wide. First off are the Kellner types. This design which has 2 to 3 elements (lenses) is an old design. They do work OK, but not as sharp as the others. Personally I think they make excellent eyepieces for daytime viewing through a short tube scope. They do have a shorter eye relief and their field of view can be narrow. They also come in a variety of other names such as MA of SMA (Modified Achromat). These are cheap EP's at just about anywhere you find them. If you get these eyepieces first off, replace them. Orthoscopic or Orthos as they are normally referred to are a little better than Kellners. They have 3 to 4 elements. These eyepieces were popular for many years until the plossl came out. They are kind of being phased out here and there. Many companies that carried them or made them are discontinuing that line and are going to better designs. Orthos' aren't bad however they have a terrible eye relief and and a narrow field of view. Plossl eyepieces are considered the best all-around eyepiece for any scope. Their 4 to 5 element design increases field of view (normally to 52°) and their cost are reasonable. Many Plossls come with a coated lens which means they absorb light reflection. This is desirable if you are near lights. There are super Plossls that exhibit a wider field of view, but to me there isn't that much difference than the normal ones. Erfle eyepieces ( 5 to 6 element) have a 60° to 70° field of view and it's like looking through a picture window, which is nice especially at low powers. One of the drawbacks of Erfles is that you lose sharpness at the edges. If you can get by that, then Erfles are OK. Ultrascopic/Ultra-Wide eyepiece (7 to 9 elements) can have up to 85° field of view and they are considered cream of the crop. They are expensive (some up to $500). These eyepieces are desirable especially with good optical scopes looking at deep sky objects. Tele-Vue/Nagler, Panoptic, Pentax are the big 3. These eyepieces are large and heavy and usually cannot be incorporated in adapters for astrophotography, except maybe the afocal method. The shorter focal length eyepieces like a 9mm or less are fantastic for planetary observing. I have heard many say that once you get an Ultra-Wide, it's hard to go back to anything else. How true. It spoils you. There is one more type and it is basically designed for one specific purpose and that is the Lanthanum type eyepieces. These too are expensive and were designed for people who wear glasses. They have a long eye relief which is nice for folks with glasses. There is of course the 2" eyepiece. These EP's come in longer focal lengths such as 50mm, 40mm and perhaps 32mm. They are expensive, but they do show a huge field of view which is handy if you "scoping" the sky for something. Note: The .965" eyepieces are too small to be of any use at higher power such as 15mm or smaller. Always try to get a scope that excepts 1.25". Accessories. What you need and what is nice to have anyway. OK, you have a scope, but all you have is two eyepieces. To me, the bare essentials include at least 2 eyepieces of different focal lengths, one long, one short. A barlow and perhaps a lunar filter. Let's talk barlows. The Barlow lens is a negative lens that increases your eyepiece power by 2 or sometimes 3. In essence, if you own two eyepieces and have a barlow, then you basically have 4 eyepieces. Example: Having a 17mm EP with a barlow will make it a 8.5mm. This is probably the most desirable accessory to have. Not quite a requirement, but close. I usually advise on getting shorty barlows because they work all around for any scope. The longer type barlows are designed for longer focal length scopes; especially refractors. The long barlows are worthless on Newtonian scopes. So think shorty. Lunar filters are a must. The moon in any telescope is far brighter that what you see in the sky. You can get two types of lunar filters. Many places sell different brands of the standard filter and they come in the 3 size variety which is .965", 1.25" and 2". You can also get a adjustable polarized filter. They can be changed to different "tints". They are basically a lunar filter, but they can be dimmer, but they do work especially on the full moon. Planetary filters or color filters are handy if you are into planetary observations. The basic set is usually red, green, yellow and light blue. Each filter enhances certain features on each planet. Example: A red filter will enable you to see the polar ice caps on Mars and a light blue will enhance the bands on Jupiter and Saturn. The list goes on. There are more than four colors and each one has their specific purpose. The violet filter helps in diminishing false color on achromatic refractors. The other filters such as light pollution filters can be helpful, however not as great as they are cracked up to be. Broadband filters filter out medium to light light pollution. They are also helpful in lunar viewing because they block certain wave-lengths and will help enhance certain features on the moon. Kind of handy in a way. Narrowband on the other hand can be more helpful. It filters heavier light pollution and can enhance certain emission type nebulae. The other types Oxy-III, or Beta's aren't really required; though they can help you see certain nebulae, they are primarily reserved for larger aperture scopes (12" or bigger) and use for the serious astrophotographer. Choosing from a Mail Order Store. I will not mention any mail order stores in this section by name (except maybe one). I will however tell about the different kinds. First of all concerning telescope manufacturers, we in the amateur circles if not the majority, consider Meade, Celestron and Orion as the "Big Three". Two of the companies, Meade & Celestron do not have their own particular stores. They just sell wholesale items to other retail stores. Orion contracts telescope manufacturers to make scopes to their specifications and then puts their Logo on them. Orion does indeed have their own store, but they do sell certain items to retail stores. If you decide to order from a mail order store, the main thing you should do is: research. Obviously no two are alike. Certain stores sell brand names at cost whereas other "smaller" stores sell a little cheaper or have "specials". These "specials" are worth looking into because you can get some really decent discounts on equipment that are either used/second-hand, demo's and blemished equipment. I would say 98% of the time there is basically nothing wrong with the equipment themselves when purchased. I myself bought a second-hand ST80 for $149 that sells brand new for $200. It had a few scratches here and there, but other than that it operated just fine. Great deals can be had if you know where to look. Each online store sells particular items for certain products and other have different ones. In Sky & Telescope and Astronomy magazines there are many ads from these stores. Most of them are reputable, some are not. This is where research comes into play. One of the best places to inquire about stores is to go on a forum and ask. Astromart is perhaps the best Astronomy based website concerning equipment on the web. It has a large list of retailers and a decent want ad section. The forum section on Equipment has heavy traffic and going there to inquire on stores is your best bet for finding out the scoop. Compare prices and look into customer service and payment methods. Some stores do not have credit card capabilities or don't have or have a poor customer service. Also there are a few stores that just sell "bulk" and customer service is just not there. Remember, always ask before you "trust" anything. Buying from Want Ads or Private Transactions. This area of telescope buying can be risky. There are many legitimate sellers that have no inclination in "ripping you off". It's the ones that do rip you off that makes it more difficult for the honest ones to make a decent deal. In the electronic age, the use of E-Mail and electronic want ads is becoming very common place, however that just creates possible problems down the road...eventually. There are certain "safeguards" and just plain common sense you need to utilize if you want a safe transaction. There are some "rules" you should always go by if you are to trust anyone with your money for anything you buy from a private seller. 1. If you receive only a Post Office Box address in any transaction, don't send the money. Some may be legitimate, but this is usually the first sign of fraud. Getting the proper address is best. It can be tracked down before and after any transaction. 2. Call the seller. Obtain the phone number from the seller and call. This establishes another form of communication other than E-Mail. This isn't a sure-fire way, but it might help you decide on the integrity of the seller's honesty. By calling and asking questions and setting up some kind of repertoire between both parties might also determine if the seller knows what they're about. It is always good practice to call before buying. 3. Usually sellers never want a personal check which is fine. Money orders and cashier checks are best. They can be traced. Pay Pal™, can be used, however there have been certain problems using a "middle-man". Sometimes you are not protected by using Pay Pal™. It is convenient, but it has been known to be abused in some fashion. There have been cases of people that have used Pay Pal™ and have had problems. Usually the seller and sometimes the buyer have been less than honest and Pay Pal™ hasn't been able to help in tracking down the problem areas. Pay Pal™ does work, but inquire about its' use before doing this. I personally don't use "middle-men". I always contact the buyer or seller and "chat" with them first. Sometimes just talking to them won't be enough. Like I said E-Ads and such can be risky. If and when you decide to purchase something through a private party, look and see if this person has had other dealings before and ask at some of the forums of such person. That is Ok to do. Be very wary...and careful. to be continued........
Choosing
The Right Telescope |