The Pleiades
Perhaps years. .. or even decades.... have gone by since the last time you looked at the night sky in a serious way. Oh, I imagine that if you were once interested in astronomy (and I assume you were, since you selected this page), you never took your eye off the night sky completely. It no doubt exercised its perpetual tug on your soul. There were probably many a night when you would glance upward at the diamonds hovering above, and think warmly about the times you sat perched beneath the stars, exploring the heavens with your telescope or binoculars.
Many of us first discovered astronomy during our youth. You probably have fond memories of your first telescope, whether received as a gift or hard earned from the fruits of your first job. Some of your most memorable astronomical images will always be the ones you experienced during the early days: your first look at Saturn, the Moon, and the Orion Nebula, to name a few.
Of the many people who discover astronomy at an early age, not all hang onto the hobby as a life-long pusuit. Many move on to other interests, or simply run out of time and interest in the midst of keeping up with the daily rat race of life. I would venture to say that most do not stay with it. But some... perhaps yourself included ... find that the fires were never completely doused. There having always been a few lingering embers, and now a little puff of wind from some corner of your life has stoked them up a bit.
Others among you may have first become involved in the hobby as adults. There's no telling what inspired you; could have been a television program such as "Cosmos", any number of NASA undertakings, or simply sitting under the stars one night and realizing that it might be worth taking a better look at what lies beyond our own planetary border. You took some action in support of that interest and started to experience the hobby at some level, perhaps buying a telescope along the way. But events in your life conspired to take you away from the hobby. Since there are so many scenarios that could produce that result, I hesitate to speculate about them. But another reason might be that you simply lost interest, or were disappointed by what the hobby, and most likely, that first telescope, had to offer. But here you are, apparently ready to give it another stab. My hope is that this page will help start you back on a successful road to experiencing the universe that surrounds you!
1. You can identify perhaps a dozen or more constellations with relative ease.
2. You know what the nine planets are, and have a basic understanding of how the planets orbit the sun.
3. You know what the Milky Way is.
4. You have used or owned a telescope before (not necessarily with great success, mind you)
If I am wrong in these assumptions, then it might be best for you to first visit a couple of my other pages first: The New Scope Owner, and the page geared for Binocular users both contain basic information that will serve you well as you get ready to dive deeper into the hobby. There is no sense in my repeating the information here.
If you have already purchased a new telescope in support of your reentry to the hobby, you still might want to visit The New Scope Owner. If you had not reached at least an intermediate level of experience during your first love affair with the hobby, you will likely pick up some useful information, regardless of the type of scope you have purchased. Stay with me on this page, however, because I hope to give you a few more advanced pointers to help you get the most out of your scope.
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The Pleiades |
Much depends on whether or not you have purchased a new telescope or not.
Part of the telescope selection process should include making decisions up front about your observing interests. Amateur astronomy has become, more than ever, a potpourri of specialties. The scope you select may well depend on whether or not you select one of these specialty areas as your primary interest:
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Saturn |
Other planets can be observed, of course. Venus and Mercury both put on fascinating demonstrations of their orbits about the Sun, in the form of waxing and waning phases. On rare occasions, these inner planets can be observed passing in front of the sun (called a transit). Uranus and Neptune are observable as relatively small disks, while Pluto is, telescopically, a faint stellar target that must be hunted down with due diligence and enough aperture. Some subtle features can be detected on all of the above, save Pluto, but it takes a very experienced eye and a fine instrument. In any event, these details pale significantly compared to those observed on Mars, Jupiter, and Saturn.
The planets are bright, so you don't need a lot of aperture for the sake of making them brighter. Increased aperture will improve resolution, however. Resolution, along with excellent contrast, are the hallmarks of an excellent planetary scope.
Scopes to consider:
The greater the aperture, the greater the resolution (i.e., you should see greater detail than with a scope of smaller aperture). There is one big limiting factor, however: the atmosphere. Your scope will only be able to effectively resolve up to the limits the turbulent atmosphere above you permits (not to mention the atmosphere a bit closer to the scope, as effected by things such as heat coming off of rooftops, and currents within the optical tube itself). Sometimes, the atmosphere will permit resolution no greater than can be achieved with a 3" scope. Other times, you will be able to realize the full potential of your scope's aperture.
Conventional wisdom says that "average" skies routinely allow the use of 6 inches of aperture. Theoretically, this equals resolution of .76 arc seconds (according to Dawes's Limits of Resolution). For this reason, a 6 inch scope is often recommended as the minimum size for a planetary scope. Now, that is not to say that smaller apertures cannot serve you well. Remember that contrast is another important element for delivering an excellent planetary image. Making out subtle details in the cloud tops of Jupiter, for example, is sometimes more a function of having great contrast, as opposed to resolution.
A well made refractor telescope rules the roost when it comes to contrast. This is by and large due to the absence of a secondary mirror, which obstructs the light path (such as in Newtonian reflectors and Schmidt Cassegrain telescopes).
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SCT Optics |
But if you live in an area of the country that has better than average skies (in terms of steadiness, not darkness), you will certainly want to take advantage of the resolution permitted by the atmosphere. And that means more aperture. Excellent conditions might allow resolution up to .33 arc seconds, or better. A 14 inch scope has resolution of .33 arc seconds, and a 17.5 inch, .26 arc seconds. Resolution beyond that would be exceedingly rare for virtually all amateur astronomers.
So, for the planetary observer, one has to start looking at a number of factors when narrowing down the list of scopes that might suit his or her needs. Some of the other considerations:
Portability
Will the scope be permanently housed in an observatory structure (lucky you!), or will you have to move it outside for each and every use? Will you be able to use it at home, or will you have to transport it to a remote observing location ?
Purchasing a scope that is too cumbersome to move and set up is tantamount to folly. A scope that is not convenient to use, will typically not be used; at least not as often as one had contemplated before the purchase. It is much better to observe more frequently with a scope of more modest aperture, rather than observe on rare occasions with a massive instrument. Place a great deal of weight (no pun intended) on the portability and ease of use factor. And be realistic about it!
To take a page from my own book on this aspect:
I observe almost exclusively from my home in Jacksonville. For years, I used a Celestron 8" Schmidt Cassegrain Telescope (SCT). While not exactly lightweight, I could pick the entire scope up and carry it out into the yard without too much trouble. A couple of more trips in and out of the house for accessories, and I was good to go.
A bit over three years ago, I decided to move up in aperture (at the time, primarily to get greater light gathering for deep sky objects). Satisfied with the years of performance I had gotten out of the C8, I opted for Celestron's CG-11, an 11" Schmidt Cassegrain on a heavy duty, high quality German Equatorial Mount (GEM). I had not anticipated the impact the size of this scope would have on my observing practices! During the first few months I owned it (having sold the C8), I found my observing time slipping significantly. Even to transport the scope just a matter of 20 feet or so into the drive way became a fairly major project. On nights when I might previously go out for a 15 or 30 minute tour of the planets or Moon, I was now sitting inside, reflecting on whether or not it would be worth the effort to set the scope up. I was finding reasons not to observe, versus the other way around.
Realizing that I had put myself into quite a pickle, I designed a mobile platform that I would use to quickly and easily roll my scope from the garage (where I keep it fully assembled). My observing time? It increased astronomically. In fact, with the new found convenience , I embarked upon what has become a fairly routine planetary observing program.
So don't underestimate the importance of the ease-of-use issue. It might well be the most important factor to consider.
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CG-11 on mobile platform |
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Astro Physics Refractor on G-11 Mount |
The Mount
If you really get into planetary observing, you will want to spend long periods (anywhere from 30 minutes on up to three or four hours) perched over your eyepiece, waiting for the best moments of seeing (i.e., steady atmosphere), thus allowing you to capture the most detail that conditions and your scope will permit. A scope that has to be moved continuously by hand only serves as a distraction from observing. For planetary work, you are also often working closer to the maximum magnification that your scope and the atmosphere will tolerate successfully. This makes tracking by hand an even more daunting task (though not impossible, as many Dobsonian owners will testify). Still, if you advance to the point where you want to make observing notes or drawings, you will really appreciate the value of a clock driven scope. Also, fine focusing is a must when trying to milk detail from the planets, and that is acheived much more easily when you don't have to also focus on keeping the planet centered in the field of view.
All other considerations aside, most of us only have so much to spend. For some, it is hundreds. For others, thousands. There is not a lot to add to this. You know how much you have to spend, based on your circumstances. The primary thing to keep in mind is that you don't forget to set aside part of your budget for additional accessories. I cover some of the most common items on my other pages.
So what should the planetary observer be looking for?
In short: A clock driven equatorial scope of at least 5 "or 6" of aperture, which can be easily used on a routine basis, and that is within your budget.
For those on a budget of $1,000 or less, a 6" equatorial Newtonian (preferably f/8 or longer) is often an excellent choice. Some manufacturers: Sovietski, Meade, Apogee, and Orion. Also within your price range will be Celestron's G5, a 5" Schmidt Cassegrain.
There are 90mm and 4" refractors available for under $1,000, but I would not recommend them for a planetary program, unless you are going to be the most casual of observers. Refractors in this class are all of the achromatic design, and suffer from chromatic abberation (i.e., an inability to bring all colors of the spectrum to the same point of focus; this typically leaves a voilet "ring" around bright objects). Though I am sometimes very surprised by the details I can observe through my son's 90mm refractor, it is never the less a bit too small of an aperture to make readily observable the kind of details you would be looking for. A routine planetary program might become rather boring after a relatively short amount of time.
If you have between $1,000 and $2,000 to spend, many more choices unfold. You can consider larger aperture Newtonians, and a variety of Schmidt Cassegrains up to 10" in aperture. There are also Maksutov-Cassegrains and Maksutov Newtonians offered by Orion Telescope that are worth a look. For the most part, refractors are still out of your price range.
Once above the $2,000 barrier, you are typically loooking at very large Newtonains (or extremely well made, such as thoughs offered by Parks.... probably the premier manufacturer of equatorially mounted Newtonians). Keep in mind the portability concerns. The higher quality, high end Schmidt Cassegrains also come into the picture. Meade's LX200 series has all the technological bells and whistles... which are all of absolutely no use for visual observation of the planets (and if you are a planetary observer, stay away from the f6.3 version of their SCT). Their 12" SCT only comes available in the LX200 package, however, for a whopping $4500. Celestron offers a 9.25 " and 11" SCT in the $2000 plus category. Both are offered in fork mounted versions (the Ultima line) and GEM versions. The two versions of the 9.25" are approximately the same price (go with the fork version... the tripod on the GEM version is suspect). The GEM version of the 11" is perhaps the best combination of mount and telescope in the world of SCT's. Previously known as the CG-11, Celestron has replaced the original mount (a superb design made by Losmandy) with their own in house unit. You can check it out at their web site. Though I have not seen the new unit first hand yet, it looks like the tripod might be one step below that of the Losmandy. If you desire the Losmandy version, don't fret: Losmandy still makes them, and they will sell you the system with a 11" Celestron optical tube assembly (note: highly highly recommend this, versus Celestron's in-house mount). Another source is Company Seven, who will sell you the same pairing. Keep in mind that the price of a CG-11 runs about $3,800 to $4,000. But if you want the best pairing of rock solid mount and a large aperture SCT, it is your best choice on the market (with the possible exception of the Takahashi line of SCT's, which run quite a bit more, inch for inch of aperture).
The infamous Questar line of scopes comes into the picture in the $2000 and up category as well. I haven't discussed the 3.5" (or Meades 3.5" , the ETX), simply because the aperture falls below what I think you should pursue. The 7" version is an excellent instrument, but extremely expensive. Meade males a 7" Mak as well, but I have not heard too many good things about that particular scope.
The upscale refractors now come into play, and are worthy of your consideration if you are indeed going to become a dedicated planetary observer. Manufacturers included Astro-Physics, Takahashi, Meade, and Vixen. Prices are in a league of their own, when compared to Newts and SCT's. Rather than run them down here, you would be best served to visit two retailers who offer a thorough description of features and prices: the aforementioned Company Seven, and Astronomics.
Cost .... What is your budget?
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The Orion Nebula |
If the planets aren't what you are after, the next most popular pursuit is that of Deep Sky Objects (DSO's). I would venture to guess that this is where most amateurs maintain their interest.
Observing DSO's becomes more and more problematic with the passing years. When it comes to DSO observing, aperture rules. The more the better, keeping in mind the portability issues. Given a choice, every DSO observer would want a large aperure instrument to keep in their backyard.
Most backayards, however, are haunted by instrusive light pollution. As populations grow, and city boundaries and suburbs expand, more and more night time lighting spills into the atmosphere, which causes the backround of the night sky to lighten. The skyglow, as it is known, drowns out the fainter stars. This is obvious to the naked eye, if you compare the view from your suburban or city site to that of a pristine, dark sky far removed from a concentration of lights.
What affects the naked eye view also affects the telescopic view. There is little comparison between the view of a DSO from a light polluted site versus a truly dark site. In fact, once you experience the view from a dark site, you may be hesitant to even take your scope out at home. Instead, you will reserve your DSO observing for those occasions when you can pack up and travel to your location of choice.
These factors have made the portability issue a bigger and bigger concern for amateurs. But advances and trends in telescope design have still made it possible to bring larger apertures to bear, and still maintain portability. Years ago, an eight inch aperture scope was considered to be large. These days, an 8" scope is looked upon as being closer to the minimum for hunting DSO's.
When you are a planetary observer, your portability issues are probably along the lines of how easy it is to move the scope from indoors to outdoors. For the DSO observer, the concern is typically more about transporting the scope dozens of miles to a dark sky site.
The size of your car, truck, or van obviously dictates the limits of your scope selection. No matter what scope you are considering, check out the dimensions of the scope, ensuring that it will fit in your trunk or other storage areas. And don't just look at the size of the optical tube; the mount, depending on the style, can be the bulkiest part to store away.
Portability
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Equatorial Mounted Newtonian |
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The Double Cluster ... A good target for a small refractor |
Don't have time for studying the sky at night? Are you interested in learning more about what makes all of those millions of stars tick? Then why not study the one closest to us: our own Sun.
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The Sun |
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The Lunar Crater Copernicus |
The factors to be considered during the selection of a telescope for a lunar observing program are virtually identical to the criteria for a planetary scope. The Moon can be a bit more forgiving in some respects, however (depending upon the type of lunar observing you will be engaged in).
In fact, I hesitate to suggest an "ideal" lunar telescope. The key is to get out there with any telescope when the Moon is present! No matter the scope, there are amazing details to be gleaned from the lunar surface. Just get out there and do it!
My expertise in both of these areas falls a bit short compared to my experience in the other areas I have already covered. So I will offer only the most general of descriptions and advice.
Serious variable star observing is truly for the most dedicated of amateurs who wish to participate in the official scientific study of stars in our own galaxy. One very positive aspect is that you do not need an ultra expensive telescope to engage in this activity. Apertures as small as 60mm can be used effectively. Quality is a consideration, however, both in terms of the primary optics and eyepieces employed.
Understanding how to estimate the brightness of an object is germane to this pursuit. On my web page devoted to Binocular users, I give a more thorough explanation of the magnitude scale used to rate the brightness of celestial objects.
Double stars can be quite pleasing to observe. The contrast in brightness and color of some doubles can make for a very pleasing sight (especially as one's imagination begins to saor, thinking about what such a close pair must look like in the sky of a planet in orbit about one of them).
Many amateurs pursue double stars for a much different reason, however: as a test for the optics of their telescope.
The ability to "split" a close pair of stars is a function of the telescope's aperture, quality, magnification employed, and seeing conditions (not to mention the ability of the observer). Theoretically, a scope of "x" inches should be able to "resolve" a double star of "y" seperation. Amateurs often test their scopes on double stars that are near (or beyond) the theoretical limit of their telescopes aperture. Splitting a pair is not always just a matter of the distance between them, however. If one is very bright, and the other dim, it can be a more difficult task (stars of relatively equal brightness are easier to split).
Splitting double stars all stems back to the discussions regarding resolution. Actually, resolution is defined by the the ability to seperate two point sources of light (i.e., the airy discs of stars), so testing resolution by using double stars is one of the best ways to test the resolving ability of your scope.
Conditions have to be right for you to pursue the splitting of stars at the edge of your scope's ability. Primarily, the atmosphere must be steady, or else the stars will blur together, their airy discs and diffraction rings intermingling. On nights of unsteady seeing, it is fruitless to test your scope.
If you have a Newtonian or Schmidt Cassegrain telescope, collimation of the optics is critical (as it is for any observing). A detailed discussion of collimation is beyond the scope of this page; I will be adding a resource dedicated to it in the future.
As you may have deduced, their is no particular "best scope" for the pursuit of double stars. Each scope has it's own limits for what systems can be "split". The fun and interest in this part of the hobby rests in putting your scope to the test. Of course, if your goal is to split the closest of doubles, then it takes large aperture, finally crafted optics.
Comets
Searching for comets is one of the most romanticized aspects of amateur astronomer. Every astronomer would love to have one named for them, but few would be willing to spend the hundred and thousands of hours it takes at the telescope to search the heavens in the role of discoverer. Large binoculars and modest telescopic apertures can be used with effect. Discipline and methodical searching practices are more the key to success. Of course, large apertures are of benefit, since it enables fainter objects to be discovered. But a wide field of view is of great value as well, since it can hasten the search.
Searching for and discovering comets is one thing. Seeking out known comets and enjoying the sight of them is another. For large (i.e., close to earth) and bright coments, binoculars are the tool of choice. A nearby comet extends across many degrees of sky, and cannot fit into the field of view of a telescope. A telescope might be used for examing the inner portion of the comet, or for examing fine detail in the tail. But by and large, the best views are going to be with binos (or for that matter, if the comet is a truly great one, simply looking at it with the naked eye under a dark sky will be a treat all by itself).
The study of meteors and atmospheric phenomena are basically naked eye and photographic pursuits. Given that this page is dedicated to the amateur armed with a telescope, I'll pass on further discussion of these areas (though meteor obsevring is quite an experience).
If that is the case, then deciding on the right telescope can be a tough chore. As you can see by now, some scopes are better suited for some tasks than others. That said, there is no "perfect" all around telescope.
I think it can be argued, however, that the one that comes closest is the 8 inch SCT. The portability offered by a "folded" optical system cures one of the primary nemesis of the amateur astronomer: convenience. Simply stated, the best telescope is the one that gets used the most often! The compound telescope is best suited in that regard, offering larger apertures for deep sky observing and planetary/lunar resolution, clock driven mounts, and long focal lengths for planetary and lunar observing (but that still provide fairly wide fields for most deep sky objects). Because of their popularity, there are also more accessories for these scopes than any other scopes on the market. They also are one of the few scopes that can be used for astrophotography, for the most part, right out of the box.
These scopes are not inexpensive, however, ranging from $1,200 to $3,000.
If your budget doesn't allow that type of expenditure, don't worry. There are lots of economical choices out there. For example, an 8" Dobsonian will keep you busy for a lifetime, giving you just as good a view as an 8" SCT, but at a fraction of the cost (but you lose some of the versatility of the SCT).
As you prepare to get back into the hobby, I offer you this:
Go slow, and don't bite off more than you can chew!
It can be very tempting to jump into this with a major investment, thinking that money will pave the way for a rewarding experience. Such is not the case. It is more important that you take the time to study. Learn the sky. Learn about the basics of optics (i.e., what makes your telescope tick). Learn to observe, rather than glancing through the telescope. Learn about the objects you are observing. Develop an understanding of the scale of our solar system, our galaxy, and of the universe itself; not just in terms of distance, but in terms of time, as well.
At the end of the road, the most valuable thing that can emerge from this hobby is that you will have a fresh understanding of the universe that surrounds you. You might gain a different perspective on your place within it, and realize that you are fortunate indeed to be among the minority of people on the face of this planet who reached out beyond the limits of our home planet and explored the heavens above. There has never been a better time in the history of mankind to participate in this pursuit. Our knowledge of the universe is growing every day. And the equipment available to today's amateur astonomer has never been better or more advanced. We are indeed fortunate to have at our disposal, even as amateurs, instruments that transcend what was available to professional astronomers in the not too distant past.
Now, if we could just get people to turn off their darn porch lights.
Have fun!
Asteriods
Meteors
Artificial Satellites
Atmospheric Phenomena
My own experience in these areas is limited, so I will be brief:
Having laid out the primary specialties within the hobby, it is more likely than not that you have not yet decided whether or not you will pursue a single niche. In fact, if you are like most amateurs entering back into the hobby after a long absence, you probably want to sample a bit of everything.