A Quick look at scopes for beginners

Before I get into the specific performance and prices of telescopes I want to give you a quick rule of thumb about three different types. If you are very much a beginner and are just looking for a telescope to get started with you probably should consider getting a refractor in the 60mm to 70 mm range. This is the perfect entry-level scope. If you are pretty sure you are going to spend a fair amount of time with telescopes and you want to get an entry level priced one that has superior performance you should consider getting a dobsonian in the eight to ten inch range. If you know a bit about astronomy, or already have a scope, and are pretty sure it will be a life-long pursuit I recommend you consider getting a Schmidt-Cassegrain scope which is a high quality compound style instrument (It is a compound of both reflector and refractor).

Style of Astronomy you want to pursue

Reflectors and refractors have very different performance under the night sky and this performance could be a factor in what type of instrument you buy. Generally, if you are going to do observing of the moon and the planets and you want the absolute best performance you should consider getting a refractor. This type of scope has the absolute best performance in this area. If you want to do a lot of deep space exploration by finding and viewing galaxies, nebulae, and other deep space objects you should go with a reflector telescope. This is because the most important thing about deep space objects is light gathering ability, and on a dollar per dollar basis a reflector gives you a substantial advantage over the refractor. You can get an eight-inch reflector for a few hundred dollars but an eight-inch refractor would cost you several thousand dollars.

Lifestyle and ease of Use

There are some other considerations that should go into your choice of scope. Are you a backpacker or camper? Do you travel a lot? If this is the case then the weight, portability, and ease of use are important considerations. Two good fits for this lifestyle would be an inexpensive four-inch reflector telescope or if you are able to spend more a Schmidt-Cassegrain in the six to eight-inch range. Both types of scopes are very portable (suitcase sized) and well suited for travel.

Should you buy a used telescope?

This is more a matter of personal preference and I can’t tell you whether a new one or a used one is right for you. But I can say that for the most part, if a scope is well cared-for it can remain practically perfect for decades. I can recommend that you don’t buy a used one if you can’t get a good hands-on look at it first. If you don’t know much about scopes you should try to find someone that does who can go with you to assess the condition and value of the one you are considering. If you are a savvy shopper, as is with most anything, you can find a fantastic value and get an instrument for less than half its retail value.

The Telescope Buyers Dilemma

One question that gets asked a lot is “What if I get a low end scope now and find out I love the hobby?” Then I have to go out and spend more on a bigger and better instrument. The money on the first telescope is pretty much wasted right? There is a small amount of truth to this but you have to consider that with your first telescope you are going to be getting a small one and just be dabbling into the hobby. If at some point in the future you spend more money and get a larger telescope you will find that your first telescope is very useful. Some nights you won’t be dragging a hundred pounds of telescope out the door and spending a half-hour to set it up. You will just want to do some light observing and the first scope will be perfect. That first, and smaller instrument, will also be a perfect gift for a child or younger sibling. I pretty handily solved this dilemma when I mounted my first refractor right onto the tube of my second, much larger, reflector telescope. It served well as a spotter scope. As a bare minimum, if you take care of your first scope you will be able to re-sell it and recoup some of your costs. But because the different sizes and types of scopes all have benefits they always useful and people who are bitten by the bug of astronomy rarely sell their telescopes. They are usually sold by people who have lost interest in the hobby.

The hobby of amateur astronomy is a wonderful hobby that can give you a lifetime of rewarding observation and photo taking. And finding the right instrument can be a bit of a challenge but with a little thought to price, lifestyle and future observing aspirations you can find one that is perfect for you.

Should you Buy a Reflector or a Refractor Telescope? – Guidelines and Advice is a post from: Meade Telescopes

The Simplest telescope you can make

There are a lot of different types you can make and the absolute simplest one you can make is composed of just two lenses. One large lens called an objective and a second smaller lens called an eyepiece. You hold one lens near your eye and another lens at arms length. You adjust the difference between the two by moving your arm in toward you.  A point will be reached where everything comes into focus.  It is as simple as that. You have a telescope.  Now you can make it much better by creating a tube around it. Get two cardboard tubes with one that can slide in and out of the other. You mount one lens on the end of one tube and the other lens on the end of the other tube.  Insert one tube into the other and then slide them in and out to find the focus.  

You can get very inexpensive lenses from a variety of surplus and online stores and they generally will only cost a couple of dollars each. I recommend you get for your primary lens a convex lens at least 50 millimeters in diameter and a focal length of between 200 and 300 millimeters. For the secondary lens I recommend you get a convex lens that is between 10 and 25 millimeters wide with a focal length of less than 75 millimeters.

There are several things you can do to make this telescope even better. First off you could make a tube out of something more durable than cardboard tubes.  Secondly,  this type of telescope will invert images so everything appears upside down which is ok for viewing the sky but is very awkward for viewing things on the earth. You can solve this by using a concave lens for the eyepiece rather than a convex lens.

You can purchase the lenses individually from online surplus stores and there are several kits readily available that give you all the necessary materials to make this kind of telescope. They also come in bulk units for classroom and group use. A kit like this typically gives you all the materials needed to make ten or more telescopes.

Getting A little more involved with your telescope making

If you want a bit more of a challenge you should consider making some type of reflector telescope. Instead of a large objective lens as the light gatherer this type uses a mirror.  A reflector can be very economical by giving you great price versus performance. Mirrors cost substantially less than lenses so for the same amount of money spent you can get a much larger and much more powerful telescope.

If you have a bit of woodworking or metal working skill and you want to tackle a project that is well within the means of a hobbyist you might want to consider making a Dobsonian telescope.  A Dobsonian telescope uses a parabolic mirror to collect the light and most Dobsonian builders buy the mirror then build the mount for the mirror to go in. The basic concept of this type of telescope is that it is easy to build and easy to use. It is pretty much just a rotating base with a telescope tube mounted on it. And this type of instrument has gotten very popular because it really is easy to use and easy to build. And one of the biggest benefits is that because it is so inexpensive to build more money can be spent on larger mirrors which can make them quite remarkable in terms of their ability to see things in the night sky.  If you are considering making this type of scope you probably should begin with one that has a mirror between six and eight inches in diameter.

Whether you build a refractor or a reflector telescope making is a very rewarding pursuit and is something you can enjoy for a lifetime. And once you start you might find that you have caught the fever and will be always looking toward building bigger and better ones.  For some people making them is half the fun.

How to Make a Telescope: Tips and Guidelines for Beginners is a post from: Meade Telescopes

A reflector telescope is one that uses a mirror rather than lenses to bend light and magnify images. Reflector telescopes, because they are easier to make and can be made in sizes much larger than refractors, are an invention that changed astronomy and our understanding of the universe.  The largest refractor telescope in the world is forty inches in diameter and reflector telescopes dwarf this in comparison. There are currently several reflector type scopes that are over four hundred inches in diameter.

Why a reflector is better than a refractor

If you are familiar with a prism or a rainbow you can understand why reflectors are superior to refractors. When light passes through glass the different bands (or colors) pass through at different angles and this causes aberrations or problems in the images. This is called chromatic aberration and it gives us distorted views of what we see through a lens.  In the time of Newton glass making and lens making was very primitive and the problems of chromatic aberration were not yet overcome. Today we can make lenses that have almost no chromatic aberration but we can’t make them very large. When a lens gets to be really large it gets very heavy and its own weight will distort the lens and ruin the image.

Newton’s telescope solved these problems. A mirror doesn’t pass light through it. It simply bounces all the light off the surface. There is no chromatic aberration at all. And because you only need to bounce light off the surface you can place the whole mirror on a supporting structure or base which takes a lot of the weight off the mirror. This way you can build much larger mirrors without any distortion.

It is commonly thought that Newton invented the first reflector telescope but it isn’t true. Credit for making the first reflector goes to and Italian Monk, Physicist, and Astronomer named Niccolo Zucchi. He published a book on Optics in the 1650’s and it is this book that inspired Sir Isaac Newton to build his own telescope. Zucchi created his first reflector around 1616 while Newton completed his first (and famous) telescope in 1670.  But while Zucchi did make some new discoveries with his telescope it didn’t work well and was difficult to make and to use.  It was Newton’s telescope that worked really well and that brought the art and science of reflectors into the world of science.

The real genius of Newton’s Telescope

All of that stuff is remarkable but there is something much more important in Newton’s Astronomy and in his telescope.  He didn’t after all, discover moons around Jupiter like Galileo did, or plot the return of a comet like Halley did. But what he did do was tie in Mathematics, Astronomy, and our understanding of the universe using his telescope and his theory of universal gravitation.  He proved mathematically that gravitation was a two way operation and that while the earth pulled on a falling apple so the apple too pulled on the earth.  This was clearly seen, calculated, and confirmed in the motions of heavenly bodies which was refined and made possible by the new science of reflector telescopes which we can credit to Newton.

 Sir Isaac and his telescope carried on with the work of Copernicus and Galileo by furthering our understanding of the universe we live in and helping us to realize there are laws that govern the whole of the universe.  And this rule holds true for falling apples and for planets revolving around stars.

The actual telescope that Newton built still survives today and is in the care of the Royal Society of London. They keep it on display in London and sometimes it travels the world as part of an exhibit.

How Newton’s Telescope Changed the World is a post from: Meade Telescopes

The eyepiece in the telescope is generally a small lens. Some telescope however, may not use lenses for the eyepiece at all. The eyepiece, in any case, is the most important element of a telescope. It is the element which lets you see correctly whatever it is that you want to focus on. These eyepieces are adjustable and are of a low power. Adjusting the eyepiece allows you to change the magnification factor. What kind of lens you use for the eyepiece is a personal choice. In today’s age, several different kinds of eyepieces are available in the market. Because of this motley available, choosing the correct eyepiece fro your requirement may be a difficult task. As a result, you should concentrate on defining the criteria you think are important for your choice. The depth of field, optical quality, sharpness, clarity, brightness, market price, barrel size and how it affects your eyesight are some of the major points of concern. However these criteria always remain individual prerogatives.

Lens designs used in older telescopes go by the name of Huygens and Ramsden. Professional astronomers are advised to not use these lenses anymore as they are not of superior quality, even though they are comparatively less expensive than other market lenses. These lenses also do not provide correction for chromatic aberration or the light circles that form around brighter objects when they are viewed.

Professional astronomers use orthoscopic lenses that are designed specifically for professional stargazing. Even amateurs will find these lenses good for their telescopes. The orthoscopic telescopes use four lenses in the eyepiece, and have a 45 degree field of vision (FOV). Since the eyepiece is the element most important to the quality of a telescope, this design is a winner. The lenses do not strain the user’s eyes, and can be used even for viewing closer objects like planets.

For a person with a moderate budget, a Barlow lens is a viable option. The design provides average quality but is a good bargain. It does not burn a hole in one’s pocket, and yet is not of inferior quality because of its cost. The range at which this lens is available starts at a low $30 and goes up to $70. The magnification factor is generally not enough for professional use, however for amateurs it should be enough. For hobbyists, it is an ideal lens.

When you’re looking for lenses for a telescope, it is important that you determine criteria that most comprehensively fulfill your needs from the lens. Adjustable lenses is a good option as it means you can view objects which are not too far, as well as distant stars with it, and thus obtain the best deal your money can buy you.

How Do Telescopes Work – Telescope Lenses is a post from: Meade Telescopes

Credit for the first reflector goes to an Italian professor named Niccolo Zucchi. He made his first scope in 1616 but the design of his scopes was not very practical. James Gregory was a Scottish Mathematician and Astronomer of the 17th Century and he is credited with having designed the first practical reflector telescope. In 1663 he published this design in his book titled Optica Promota. But he didn’t build the first working model until ten years later with the help of scientist Robert Hooke. It was in this ten year period that Sir Isaac Newton built his famous Newtonian telescope (1670). So the Gregorian telescope predates the Newtonian in design but Newton’s was the first to be built.

How the Gregorian Telescope works

To understand how the Gregorian reflector works we will first take a look at the Newtonian telescope. In the Newtonian a parabolic mirror placed at the bottom of a tube and it focuses light back up the tube to a flat mirror that directs it out the side of the tube to an eyepiece.  The eyepiece is on the side of the tube. In a Gregorian design the parabolic mirror is at the bottom of the tube and it focuses light back up the tube but the second mirror is an ellipsoid and it redirects the light back down the tube to the eyepiece through a hole in the center of the large primary mirror. This type of telescope has the eyepiece at the bottom.

The benefits and shortcomings

Newton’s telescope has one parabolic mirror and one flat mirror while Gregory’s has a parabolic as its primary mirror and an ellipsoid as its secondary. Additionally, Gregory’s primary mirror needed a hole cut in the center of it. These things mean it is a much more optically complex instrument and much more difficult to make. Newton’s design is much easier to make.  This is probably why it took Gregory ten years to make his first working model.

The Gregorian does have some benefits over the Newtonian style scope. The ellipsoid secondary mirror is placed at a point after the focus of the light. This configuration, in conjunction with an eyepiece, provides an erect or right side up image while the Newtonian telescope gives an upside down image. This is a big benefit if you are using the telescope for terrestrial viewing.  And because of this inversion of image after the secondary mirror it allows a baffle to be placed inside the tube. This baffle prevents unwanted light and heat from reaching the primary mirror. This is a very useful tool when a telescope is meant to be used for solar observations where heat is a big concern. For this reason the Gregorian design is sometimes still used for telescopes that will be used for solar observations.

The Gregorian design for a telescope is not used very often in modern times. It has been changed and much improved by the Cassegrain telescope. But the Gregorian does find limited use occasionally as a finder scope that accompanies a larger scope. This is because of the nature of it displaying properly oriented erect images.  And because of its ability to have a baffle inside it is also sometimes used for telescopes built for solar observations.

Gregory’s telescope design is not much used in modern times but it was the forerunner and inspiration for many of today’s telescope designs.

 

The Gregorian Telescope – the First Practical Reflector is a post from: Meade Telescopes

First and foremost, there are three basic types of telescopes: reflector, refractor, and combo catadioptric.

· The reflecting telescope (or Newtonian) basically uses a concave design and mirror lens to reflect light off an object in the distance, to perceive it more closely. These types offer great light-gathering technologies, are typically stationary, and are the least expensive of the three. They are the best beginner telescopes for those interested in casually exploring the night sky at a value price.

· The refractor telescope works by using a number of lenses to refract or bend the light that is being transmitted by a distant object, to gain a more focused magnification from the eyepiece. Refracting telescopes are comparatively much more expensive; but also offer sharper, high-contrast, accurate views of the stars, planets, and moon above. It is also worthy to note that another bonus of the refractor is that it performs with aplomb in all atmospheric conditions, unlike the former.

· Lastly, is the catadioptric (example: matsutov-cassegrain) telescope. This type compasses both the bent lens system of the refractor telescope, as well as the mirror technology of the reflector telescope. Middle ground of all three, the catadipotric boasts high-quality precision, resolute optical technologies, convenient portability, and promises a more digestible price range than the refractor models.

Once decided upon what type of telescope you'd like to invest in; the next step is figuring out what technical specifications to look for, as far as magnification, aperture width, focal length, resolution, etc.

· Magnification is the first number listed in the formula usually expressed for a telescope, example: 100X5. The magnification in a 100X5 would be 100, and means that this telescope will give you 100 times the magnification you would perceive an object with than the naked eye. It is necessary to recognize that more is not always better, because the more the object is magnified, the less light is allowed to view it with.

· Aperture is the second number denoted by the formula (In this case: the 5, of the example 100X5), and is simply the diameter of the objective lens. The aperture measurement tells us how much light will be allowed in offering clarity to the object you are looking at. The larger the diameter, the more light allowed; and so it is necessary to adequately balance magnification (power) with appropriate aperture.

· Focal length (represented in millimeters) is the length that light has to travel within your telescope to reflect and perceive the object. The higher the focal length measurement: the higher the magnification, the larger the image, and the smaller the field of view.

· Resolution is the telescope's capability to render the object's image in detail. The higher the resolution, the sharper the details you will be able to perceive. This is directly in relation to the aperture width, as discussed earlier: the larger the aperture, the better the resolution.

Once you recognize the different types of telescopes, and the relationship of the basic specifications as listed above; you can begin to maneuver your way around selecting one for yourself. How casual your intended use, what objects you'd like to view, and how much you'd want to invest; all play a big part in determining the best telescope for your uses; but now armed with the basics of buying a telescope, you're sure to find the perfect new optical device with ease.

Buying A Telescope: Tips For First Timers is a post from: Meade Telescopes

Well, you have it. Here is the article, that can help you get into astronomy. First it is important to consider a few points, when wondering how to buy a telescope. The first and obvious step, is buying a telescope. However, there are some other parts, which go to make your hobby in astronomy, so much more fun.

You need 3 things to get the most out of astronomy, and 1 other item, which I recommend:

1. A telescope (this telescope buying guide, should help with that!)

2. A star atlas

3. A good practical book on astronomy and telescopes

* Optional

4. A notebook

Let us look into these necessary items to get the most out of astronomy. Remember, you can easily get into astronomy, by studying and learning the constellations. Some people in our human history, devoted there lives to constellations, some even to just 1 or 2!

* 1. How To Buy A Telescope?

Your first step before buying a telescope, is to consider what you want it for. Remember, telescopes are scientific instruments. This is an investment, and generally more you pay, more better telescope you get, which can literally last a life time.

If you have been wondering how to buy telescopes, you have come to the right place! Buying a telescope requires buying from either 1 of 3 places. From a specialized telescope shop, though these are not always easily found. The next is through mail order and the third, which is the easiest, is online.

There are 2 main types of telescope, one is reflector telescopes (catoptric), and refracting telescopes (dioptric). One has a big mirror, and the other is longer, and slimmer. They both pretty much do the same objectives. However, many people prefer the reflector for deep space viewing.

* 2 & 3 - A Good Star Atlas And Practical Astronomy And Telescopes Book

Getting the most out of the science of astronomy, is not about buying the biggest telescope or the high price you paid. Instead it is about knowing what is where, and where to look.

Galileo's telescope was so inferior to today's telescopes readily available, that he said that Saturn has ears! However, he still invested a lifetime into the study of these objects.

The key to knowing where to look, is with a good star atlas, and a practical astronomy book, designed for small telescope use. A book called - Turn Left At Orion, seems to be the most popular, and easy to follow.

* 4. A Notebook

Viewing Saturn, Jupiter, and the Moon, can be fun home scientific tasks, but what happens next? We get bored! The truth is, to get the most out of astronomy, is to treat it as a science. Even if you are the worst painter, you still can record a detailed picture of the Moon's craters over days, and see the differences. This will go a long way in the future, and will allow you to look back, and see what many people will never see, and all because you invested into the science of astronomy.

Telescope Buying Guide – How To Buy A Telescope? is a post from: Meade Telescopes

Selecting the proper type

The refractor type telescopes best suit for watching moon and major planets. Refractor telescopes are long & thin, and known for their sharp, detailed and contrasty images. They collect light through multi-element lenses. If you are just a starter then a small, quality achromatic refractor of 60 to 90 mm aperture would be a good one. The best thing about a refractor telescope is that they are inexpensive, portable and almost maintenance free. A refractor telescope is also useful when you will be mostly observing from city or the surrounding areas where the night skies are lightly polluted.

Reflector telescopes are also known as Newtonian telescopes. They are good for planetary as well as deep-sky viewing. However Newtonian telescopes are more fragile and need more maintenance than others. These telescopes collect light with a curved, concave mirror and with the help of their large apertures, they show fine, highly-resolved images. The reflector scopes are not suitable for terrestrial viewing because they produce an upside-down image.

Catadioptrics use both lenses and mirrors to collect and focus the incoming light. They are also called compound telescopes. Catadioptrics scopes are considered the most versatile telescopes and gives great all-around performance. They use a large aperture in very compact tubes. They show magnificent images of the moon, planets and faint deep-sky objects, when viewed in dark skies away from urban areas. These scopes are best suited for astrophotography. Compared to other two, these scopes have a wide range of accessories available. They can be entirely computer controlled.

Factors affecting the performance of a telescope

Aperture: Telescopes collect light from distant objects and focus it to produce images. The light collecting capacity of a telescope is the most important feature. It is the aperture of scope (diameter of mirror or lens) that is responsible for gathering light. Larger the aperture, the more light gathered, the more you'll see.

Telescope Mounts: There are three basic mounts for telescopes altazimuth, Dobsonian, or equatorial. Altazimuth is the simplest type of mount, providing up-down, left-right motions. It is mainly recommended for terrestrial viewing and casual stargazing. The Dobsonian mount was basically designed for easy maneuvering of large reflectors of more than six inches. It is a boxy altaz-type mount sitting close to the ground. Equatorial mounts are designed for the purpose of astronomical viewing. These mounts are more expensive and complicated than the altazimuth mounts. With the help of these type of mounts users can track or follow the motion of celestial objects through the sky with a single manual hand control.

Magnification: Magnification should never top the priority for buying a telescope. The quality if image degrades with magnification. Practically 300X is maximum magnification for good quality images. Telescope's magnification is also known as its power and it is adjusted by changing eyepieces. Ideally there should have been three eyepieces for the magnification of a scope: one low, one medium and one high. Lower powers of 30 - 50X are recommended for observing galaxies, star clusters and nebulae as they are spread over a wide area of sky. For observing the rings of Saturn, Jupiter, studying craters and valleys of the Moon's surface medium power of 80 - 100X are advised. Higher powers of 150 - 200X allow the astronomers to observe mountain peaks and fine lunar detail, the surface features of Mars.

I am a laboratory analyst by profession working in this industry from last 10 years. I have been running a site http://www.laboratoryequipmentworld.com on laboratory equipments. It includes the largest range of laboratory apparatus and other updated info on market, trade fairs, news, etc.

A Telescope Buying Guide for Beginners is a post from: Meade Telescopes

Types of telescopes:

There are three basic types of telescopes -- Refractors, Newtonian reflectors, and Catadioptrics.

Newtonian Reflector Telescopes:

Newtonians usually use a concave parabolic primary mirror to collect and focus incoming light onto a flat secondary mirror that in turn reflects the image out of an opening at the side of the main tube and into the eyepiece.

Refractor Telescopes:

Refracting telescopes have an objective lens at the front of the tube. The light exits out through the back of the tube to the eyepiece. Since many observations are made high in the sky, a right-angle diagonal is used to avoid neck strain. This also provides an upright image making them suitable for terrestrial observations. A refractor has several advantages over other designs. The tubes are enclosed so that dust and moisture do not enter the tube, they have fixed optics that do not normally require collimation, and they do not have a central obstruction which reduces the light entering the tube. A refractor typically will give higher quality images of planets than other telescopes of similar aperture.

Catadioptric Telescopes:

Telescopes using a combination of both mirrors and lenses are called catadioptrics. There are many different designs. Examples of these are the Schmidt-Cass grain and the Maksutov-Cassegrain. Usually a full aperture lens is used to correct aberrations in a compound reflecting telescope. The corrector lens also increases the performance of the instrument as air currents are eliminated. The main advantage of the design is that, because the light path is folded back on itself, it provides a very portable, short physical length telescope with a long focal length.

Benefit:

1. The aperture of a telescope is several times larger than the aperture of human eye so that the objects that can not be normally seen by unaided eye can be seen. Light- gathering power of a telescope is proportional to the area of its aperture and hence depends on the square of the radius of the mirror. Therefore a 20 cm diameter telescope collects four times more photons than a 10 cm diameter telescope.

2. A telescope can be equipped to record light over a long period of time, by using photographic film or electronic detectors such as photometers or CCD detectors while the eye has no capability to store light. A long-exposure photograph taken through a telescope reveals objects too faint to be seen with the eye, even by looking through the same telescope.

3. A third major advantage of large telescopes is that they have superior resolution, the ability to discern fine detail. Small resolution is good. The resolution is directly proportional to the wavelength being observed and inversely proportional to the diameter of the telescope.

What Are Telescopes and Its Benefit? is a post from: Meade Telescopes

The largest Refractor telescope

Refractor telescopes are renowned for their absolute sharpness of image because they are composed of very large lenses of compounds of glass which gives them crystal clear images. But they are extraordinarily difficult to make in a large size. Their own weight distorts their shape and makes them unusable above a certain size.

The largest refractor in the world is the Yerkes telescope which has a primary lens that is 40 inches in diameter.  It was completed in 1897 and was built by the famous master optician Alvan Clark. It represents the pinnacle of refractor telescope making and no larger one has since been built in the hundred years since. Reflectors are much more feasible for larger sizes and there are many of this type that are extraordinarily large. It is with reflectors that we achieve very large instruments.  

Reflector telescopes come in two different types. The first type is the single mirror type where a single piece of glass is cast and polished to make the primary mirror. The second type is the segmented mirror where a series of hexagonal mirrors are assembled together into a single large mirror. This type of mirror looks much like the honeycomb from a beehive and this new technology is allowing telescope makers to make instruments larger than ever imagined.

The largest single piece of glass telescope in the world is the Large Binocular Telescope (LBT) in Arizona. It is a telescope composed of two separate mirrors that are side by side and work in tandem. The light from both of them are blended into one single image. Each mirror is 8.4 meters (330 inches) in width and when used together they create the equivalent of a mirror that is 11.8 meters (464 inches) across which is currently the largest light collecting size on Earth. It is located in Mount Graham International Observatory in Arizona.

Segmented mirrors pose technology challenges that have been overcome in the past decade and now these multiple mirror scopes are being built in extremely large sizes that cannot be rivaled by single piece mirrors. Of the segmented telescopes where a series of honeycomb shapes are assembled together into a single telescope there are three different observatories with these largest of mirrors.

The South African Large Telescope (SALT) is the largest primary mirror scope in the world and it has a segmented mirror that is 11 meters (433 inches) across.

The Gran Telescopio Canarias or GTC is located on the island of LaPalma Spain and it has a segmented primary mirror that is 10.4 meters in diameter (409 inches) which makes it the single largest mirror in the world.

The Keck Telescopes are a pair of telescopes located at the Keck Observatory in Hawaii. Each mirror is ten meters (400 inches) in diameter.

Bigger Telescopes to come

There are even larger telescopes currently in the proposal, development, or construction stage.  Technology improvements over the past decade have made a new scale of telescope possible and this new scale is referred to as ELT or Extremely Large Telescopes and it is the next generation to come.  ELT’s are telescopes that are more than twenty meters in diameter which is double the size of existing telescopes.  And this doubling of size gives significantly more than double the light gathering power. Most of these scopes will be of the segmented mirror type but one notable exception is the Giant Magellan telescope which will be composed of seven spherical mirrors constructed together so they act as a single mirror.  This project is scheduled for completion in 2016. It will be located in Las Companas Observatory, Chile.

The Thirty Meter Telescope (TMT), which is currently in development, will be thirty meters across and composed of segmented mirrors.  It is expected to be a telescope of unmatched performance and is predicted to be able to image planets circling other stars.  The current time line for this project is for it to be completed somewhere around 2017 – 2018.

What about the Famous Hubble Telescope?

The primary mirror in the Hubble is 2.4 meters across (94.5 inches) which makes it rather small compared to some of the giants listed in this article. So then why is it the most spectacular telescope ever created? The big advantage the Hubble has over all the other telescopes is that it doesn’t have to peer through the soup of Earth’s atmosphere.  And this advantage is staggering.  That is why the Hubble has brought us some of the most extraordinary images ever recorded.

What comes after the Hubble?

NASA is currently working on its next generation space telescope. It is called the James Webb Space Telescope (JWST). The primary mirror will be 6.5 meters (21.3 feet) in diameter.  Launch is planned for 2013.

Since the invention of the first telescope 400 years ago man has been building ever larger telescopes. The telescopes to come will bring us images of planets around other stars and who knows, they may bring us images of the very birth of the universe we live in.

A Look at the Biggest Telescopes in the World is a post from: Meade Telescopes

astronomical telescope advice plz!?

I got a star 70060 starter astronomical telescope from telescopeplanet.co.uk for christmas and i need some advice on how to get the best results from it, it's a
60mm Refractor Telescope with
3 Eyepieces (SR4mm, H12.5mm, H20mm, 1.5X erecting eyepiece & 3x barlow Lens)

Your scope will ideally support a maximum magnification of around 120x; that would depend on the quality of the optic and the prevailing conditions.

We should begin by losing your barlow lens and your erecting eyepiece. They are useless and the quality on these (provided with cheap starter scopes) is usually so low that they would be useless on any scope, of any size.

Then you should adjust your finder scope so that it is aligned with your main scope. Just aim the main scope at some conspicuous target (like a sign or tower in the distance, and adjust the finder until it points at exactly the same spot. You have a very poor excuse for a finder; but, if you align it correctly you should be able to get some help from it. The finder serves as a wide angle targeting device; the idea is to get it close enough so that you can see the object in the main tube.

Once you get that done, insert your diagonal into the focuser, and then your 20mm eyepiece. This should yield around 35x which is plenty to make out the brighter planets. Also, be aware that objects which are higher up in the sky will look much clearer then those near the horizon; you have to cut through more atmosphere when looking at the lower angle.

Today, both Jupiter and Mercury were very low on the Western Horizon at dusk; the season for Jupiter has passed and we will not be seeing much of it again until again until late spring. Mercury is Always an elusive target; it is never more then 15 degrees or so from the Sun. So, unless you have installed a full aperture solar filter, you are limited to catching periodic glimpses of Mercury at dusk or dawn.

Venus was that very bright star like object that you saw near the Moon, it will be back again tommorow, so you will have another chance to look at it. At 35x you should be able to make out what looks like a tiny version of our Moon during first quarter. If you look closely, both mercury and Venus go through phases.

Saturn comes up from the due east at around midnight. The ring alignment right now is at a right angle to us so they are edge-on to us. At 35x you should be able to see a small sphere with a line through it; if not, switch to the 12.5mm eyepiece and try it again at 56x. If the conditions are right you will see Satirn's giant moon Titan as a small point of light out beyond the end of the rings.

As you wait for Saturn to climb to a good position, you can turn your scope toward Orion. The Nebula is bright enough to be seen as a dim grey cloud with a 60mm; you should also be able to make out Trapesium, the four bright stars that sit as a tight little square right in the middle of the nebula.

Clear Skies!

For More Astronomical Refractor Info Click On The Links Below

	Celestron 21061 AstroMaster 70 AZ Refractor Telescope
	TE3) Celestron astromaster 70AZ scope

	BARSKA 40070 Starwatcher Compact Refractor Telescope with Table Top Tripod And Carrying Case
	The Barska 40070 Starwatcher Compact Refractor Telescope with Table Top Tripod and Carrying Case is an ideal telescope for the aspiring amateur astronomer. Ideal for students or those interested in learning more about the night sky, the 70mm objective lens can zoom up to 300x power...

	Celestron 21024 FirstScope Telescope
	FirstScope Telescope Official Product of the 2009 International Year of Astronomy. Ideal astronomical entry level telescope. The FirstScope Telescope pays tribute to Galileo Galilei and may of history's most notable astronomers and scientists...

	GSI Super Quality Land And Sky 50mm Refractor Telescope With TP-8 Aluminum Tripod - 72x Power Magnification - Optical Glass Lens and Metal Body - Includes 2 Eyepieces, For Terrestrial And Astronomical Use
	This Great New Telescope From GSI Will Meet And Exceed Your Expectations! Easy, User-friendly Setup, And Unbelievable Views Through The Ultra Clear Lens, You Will Discover The World Like Never Before. Extremely Affordable, It Is A Great Alternative To Other Pricier Models Out There!

	CELESTRON Powerseeker 50 Refractor Telescope
	The Celestron® PowerSeeker 50 telescope is a great way to open up the wonders of the universe to the aspiring astronomer. It's portable yet powerful with ample optical performance to excite any newcomer to the world of amateur astronomy.

	Celestron 21068 SkyScout Scope 90mm Telescope with Sky Scout Mounting Braket
	90mm (3.5”) diameter refractor, 660mm focal length (f/7), altazimuth mount with pan handle and built-in clutch, 6x30 finderscope, 40mm eyepiece (16.5x) - 1.25”, 10mm eyepiece (66x) - 1.25”, adjustable SkyScout mounting bracket, erect image fully coated optics, adjustable height stainless steel leg tripod with accessory tray, “The Sky Level 1” CD-ROM

	Celestron 21045 114mm Equatorial PowerSeeker Telescope
	I love bargains, so I was eager to try out Celestron's new Powerseeker 114 Newtonian reflector telescope. With its 4.5-inch mirror, Celestron's Powerseeker 114 gathers three times more starlight than popular 60mm refractors...

	Celestron 21036 PowerSeeker 70AZ Telescope (Black)
	Celestron's value priced PowerSeeker 70AZ is an affordable entry level telescope with some nice extras like a correct image prism and "The Sky" astronomy software included. The package also includes an Alt-Azimuth mount with adjustable aluminum tripod, high and low power eyepieces, a 3X barlow lens, and a 5 power cross hair finder scope...

	Celestron 21041 60mm PowerSeeker Telescope
	Celestron's value priced PowerSeeker 60 is an affordable entry level telescope with some nice extras like a correct image prism and "The Sky" astronomy software included. The package also includes an Alt-Azimuth mount with adjustable aluminum tripod, high and low power eyepieces, a 3X barlow lens, and a 5 power cross hair finder scope...

	GSI Super Quality Land And Sky 60mm Refractor Telescope With Aluminum Tripod - High Power Magnification - Optical Glass Lens, Metal Body, ND Moon Filter - Includes 3 Eyepieces, For Terrestrial And Astronomical Use
	This Great New Telescope From GSI Will Meet And Exceed Your Expectations! Easy, User-friendly Setup, And Unbelievable Views Through The Ultra Clear Lens, You Will Discover The World Like Never Before. Extremely Affordable, It Is A Great Alternative To Other Pricier Models Out There!

The development of building a telescope was greatly aided by the construction of the achromatic lens.

The Achromatic Refractor

In 1733, the achromatic lens was invented by Chester Moore Hall, an English barrister. This was accomplished by combining a convex crown and a concave flint lens in such a way that their focal lengths were inversely proportional to their dispersions.

Although a number of telescopes were made according to Hall's instructions, the benefits of the achromatic lens do not appear to have been made available to the public until John Dollond invented it independently in 1758, and patented it. Dollond's efforts led to a demand for clearer glasses of more varied densities and of less equal dispersions, needed to improve achromatism, and chemists pursued experiments in learning how to control the refractive indices of melts, and in the pouring of large disks of limpid, homogeneous glass.

Altogether, excellent progress began to be made, and by 1800 achromatic objectives 6" in diameter were being turned out. Some of the best glass had been manufactured by Guinand, a Swiss who worked with Fraunhofer from 1805 to 1814. Fraunhofer produced a number of splendid achromats up to 9" in diameter.

Dollond was making refractors (spyglasses) with single-lens objectives as early as 1742, his price for a 2-foot telescope then being 7s 6d. In comparison, in 1762 he sold a 2-foot telescope with a two-lens objective (achromat) for 2 guineas. The lens diameters in each case were just under 2".

In 1783, with a view to combining the benefits of the wide field of Huygens' eyepiece with a means of making micrometric measurements of an image in the focal plane, Jesse Ramsden, an English optician, designed the compound eyepiece. Building a telescope was becoming more like the process undertaken today.It can be seen that a measuring device, such as adjustable parallel wires, set in the focal plane would be magnified along with the image. Measurement of an image in the focal plane was by no means a new idea; probably this had been first accomplished by Gascoigne, an Englishman, about 1638.

With the advent of the achromatic lens, the erecting or terrestrial eyepiece assumed considerable importance. This type of eyepiece was first suggested and used by Kepler, and improved in design about 1645 by Antonios Maria v. Schyrle, a Capuchin monk better known as Rheita. It is mentioned here because it spelled the rise of the refractor and the decline of the Gregorian for terrestrial use

In the early part of the 19th century, small achromatic refractors were being manufactured by several concerns. For those not having the means to buy achromats, telescopes with single-lens objectives continued to be made. Enterprising opticians were also offering lens sets that could be assembled into simple refractors.

The Modern Era

The method of chemically depositing silver on glass discovered about 1840 by Justus von Liebig, of Nuremberg, was successfully applied to a small glass telescope mirror in 1856 by Karl Steinheil, a German physicist, and independently in the following year by Jean Foucault, the famous French physicist.

Various processes of plating glass with metal for the making of mirrors had been known and practiced for centuries, but for one reason or another, the coatings were unsuited for front-surface reflection.

Then, in 1858, Foucault announced the development of his amazingly delicate and simple test for a concave reflecting surface, using an illuminated pinhole and a straightedge placed in the vicinity of the center of curvature of the mirror. The pinhole and straightedge were the outgrowth of earlier experiments in which simultaneous microscopic comparison was made of a pin point, likewise placed at the center of curvature of a mirror, and its reflected image, which was caused to fall alongside.

The last speculum of note to be constructed was one four feet in diameter, made by Grubb in 1870 for the Melbourne Observatory. Silver-on-glass mirrors replaced the more expensive and difficult-to-work speculum. It tarnished, but not nearly so quickly as speculum, and it could be removed by chemical means and a new coating applied without upsetting the figure of the glass surface.

Building a telescope was becoming closer to being constructed in the style we know it today.

You'll Soon Be Gazing At The Stars Through Your Very Own Telescopes

Visit: http://www.maketelescopes.net

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Many thanks for reading our Astronomical Refractor article

Astronomical Refractor is a post from: Meade Telescopes

For More Reflector Telescope Tripod Info Click On The Links Below

	SkyScanner 100mm Reflector Telescope and Tripod Bundle
	If there isn't a table at your favorite observing spot, we now provide our Orion SkyScanner 100mm TableTop Reflector Telescope bundled with a sturdy field tripod so you can scan the skies anywhere! The included field tripod is adjustable with a height range of 20" to 34...

	Orion StarBlast 4.5 EQ Reflector - Telescope - f/4.0 - reflector
	Considering how many adults have told us they love our StarBlast "mini Dob," we weren't surprised that some of them suggested we offer the StarBlast optical tube on a full-size telescope mount. Sounded like a good idea to us...

	FunScope Reflector Telescope and Tripod Bundle
	We now provide the popular FunScope Reflector bundled with a sturdy field tripod so you can have fun enjoying the night sky anywhere, even if there isn't a table nearby to set the telescope on! The included field tripod is adjustable with a height range of 20" to 34...

	Celestron 21024 FirstScope Telescope
	FirstScope Telescope Official Product of the 2009 International Year of Astronomy. Ideal astronomical entry level telescope. The FirstScope Telescope pays tribute to Galileo Galilei and may of history's most notable astronomers and scientists...

	Rokinon 1000 x 114mm Reflector Telescope with Tripod (Blue)
	1141EQ1 Features: -Reflector telescope.-Boasts paraboloidal mirrors to ensure sharp images, free of spherical aberration effects.-Focal length combine to produce crystal clear images even at high power magnifications...

	Celestron 31045 AstroMaster 130 EQ Reflector Telescope
	If you're looking for a dual-purpose telescope appropriate for both terrestrial and celestial viewing, then the AstroMaster Series is for you. Each AstroMaster model is capable of giving correct views of land and sky...

	Orion SpaceProbe 3 Altazimuth Reflector Telescope
	Orion's surprising little Spaceprobe 3 has been picked by independent reviewers as one of the best telescopes in its price class. Unlike similar telescopes seen in discount stores, Orion has refined the Spaceprobe 3 by paying attention to the little details, and that make this telescope a great value...

FunScope 76mm Tabletop Reflector Telescope

Fun indeed! You'll enjoy hours of stellar exploration with this amazing little telescope. Designed specifically with first-time telescope buyers in mind, the FunScope is a great way to test the waters of stargazing - affordably! But what can you see with it? The FunScope features a 76mm polished spherical mirror, allowing you to capture 60 percent; more light than a typical 60mm beginner's telescope...

	Emerson Refractor Telescope with Tripod
	Get a closer look with the Emerson Refractor Telescope and Tripod. It makes a great companion at sporting events, under the night sky, or on a bird watching trek.

	BARSKA 40070 Starwatcher Compact Refractor Telescope with Table Top Tripod And Carrying Case
	The Barska 40070 Starwatcher Compact Refractor Telescope with Table Top Tripod and Carrying Case is an ideal telescope for the aspiring amateur astronomer. Ideal for students or those interested in learning more about the night sky, the 70mm objective lens can zoom up to 300x power...

A telescope is such a great tool to witness the marvels of heavenly creation. But do you know about the various factors that add value to a telescope before you buy it. If not, take some time to read through some of the points that count in the purchase of a telescope. Initially, you can seek the help and advice of an astronomical club, organization or society in your local area and they can enlighten you on the buying as well as the working of a telescope. But, before buying a telescope, you must be careful about the tens of thousands of telescopes being flooded in the market. They may comprise lenses that are figured improperly, eyepieces that are cheap and unusable sold in the guise of magnification ranging from 400x, 640x up to 1200x, which actually they fail to provide.

One of the primary attributes of a telescope is the magnification as discussed previously. Therefore, compare similar telescope by mode of aperture - the size of objective lens or a mirror. The magnificent Galaxy in Andromeda considered one of the most splendid sights in the sky is eight times the size of full moon, but much more dimmer. So a magnification of 20-40x is all that you need to view it. You can of course look for larger telescopes, but you should be careful as there is a higher price tag every time that come along with it you go for a larger one. A small telescope with exceptional optics can help you see more than a bigger scope having mediocre optics. For example, 3.5" Questar will be better off to watch the Galaxy in Andromeda than a 21" telescope.

If you want to choose between a big scope that fits into your city garden polluted by light, and a small scope that you will be able to carry out to remote and dark areas, then it is better to go for a small scope that is easily transportable. Again experts in using telescopes would suggest you to purchase a smaller scope because the smaller your scope, the more often you can make use of.

Look out for a good mount as it as important as the telescope itself because cheap mountings can wobble your focus a lot and make your focusing absolutely impossible. With the help of steady, rock -solid mounting your focusing will be much more precise. Add to that a stable tripod that will make your viewing a pleasure. Just follow these simple tips before you go on to buy a telescope and if required you can also consult with an expert astronomer who can provide you comprehensive knowledge on scopes.

Before buying telescopes, spend some time on Telescope Review websites to read reviews of latest, best selling telescopes and you can compare the features and specifications that suits you, then you can go for popular brands like Celestron Telescopes, Taso, Meade, Seben and other popular brands for best product.

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Many thanks for reading our Reflector Telescope Tripod article

Reflector Telescope Tripod is a post from: Meade Telescopes

I have a Meade 10" reflector telescope, and the primary mirror seems to be loose. It wobles. How do I fix it?

Meade makes two kinds of reflectors--Newtonians and Schmidt Cassegrain. You didn't say which.
The Newtonian has adjustment bolts in the back for collimation. You will have to go on line or read instructions from Meade as to tightening and adjusting these properly to get best optical alignment.
There are mirror clips to gently (GENTLY!!!) retain the mirror in the holder cell. These can be checked for securing of the mirror without distorting it due to excess pressure.
On the Schmidt Cassegrain, this is known as "mirror flop". There are several cures for this, so details can be gotten from on line sources, astronomy club members, or Meade itself (not advised).

For More Reflector Telescope Info Click On The Links Below

	Orion SkyScanner 100mm TableTop Reflector Telescope
	Although perfect for beginning stargazers, this telescope is not a toy! The Orion SkyScanner 100mm TableTop Reflector is just the right size - large enough to see night sky objects yet compact enough to sit on a desk...

	Orion StarBlast 4.5 EQ Reflector - Telescope - f/4.0 - reflector
	Considering how many adults have told us they love our StarBlast "mini Dob," we weren't surprised that some of them suggested we offer the StarBlast optical tube on a full-size telescope mount. Sounded like a good idea to us...

	Orion SpaceProbe 3 Altazimuth Reflector Telescope
	Orion's surprising little Spaceprobe 3 has been picked by independent reviewers as one of the best telescopes in its price class. Unlike similar telescopes seen in discount stores, Orion has refined the Spaceprobe 3 by paying attention to the little details, and that make this telescope a great value...

	SkyScanner 100mm Reflector Telescope and Tripod Bundle
	If there isn't a table at your favorite observing spot, we now provide our Orion SkyScanner 100mm TableTop Reflector Telescope bundled with a sturdy field tripod so you can scan the skies anywhere! The included field tripod is adjustable with a height range of 20" to 34...

	Celestron 31045 AstroMaster 130 EQ Reflector Telescope
	If you're looking for a dual-purpose telescope appropriate for both terrestrial and celestial viewing, then the AstroMaster Series is for you. Each AstroMaster model is capable of giving correct views of land and sky...

FunScope 76mm Tabletop Reflector Telescope

Fun indeed! You'll enjoy hours of stellar exploration with this amazing little telescope. Designed specifically with first-time telescope buyers in mind, the FunScope is a great way to test the waters of stargazing - affordably! But what can you see with it? The FunScope features a 76mm polished spherical mirror, allowing you to capture 60 percent; more light than a typical 60mm beginner's telescope...

	Celestron 31042 AstroMaster 114 EQ Reflector Telescope
	B000MLL6R8 Celestron’s AstroMaster 114 EQ reflector telescope offers more than three times the light gathering power of 60mm beginner scopes in a system that is compact yet powerful. The package includes a new version of Celestron’s CG-2 equatorial mount with a rugged steel tripod...

	Orion Soft Case for StarBlast 6 & 6i Reflector Telescopes
	A convenient way to carry and store the Orion StarBlast 6 and StarBlast 6i IntelliScope!

	Celestron 21024 FirstScope Telescope
	FirstScope Telescope Official Product of the 2009 International Year of Astronomy. Ideal astronomical entry level telescope. The FirstScope Telescope pays tribute to Galileo Galilei and may of history's most notable astronomers and scientists...

	Vivitar Viv-Tel-76700 75x/350x Reflector Telescope
	Vivitar's TEL-76700 is Vivitar's first astronomical telescope to feature Reflector based architecture and technology. This model is built of the finest grade materials, using Vivitar's own coating, lenses, and mirrors...

A telescope can be a wonderful tool for those who have always been fascinated by the night sky. With the right model you may be able to see the planets, stars, and the moon with greater clarity than you had ever imagined before. But, how will you know which model is right for you? You can choose from a reflective or a refractive model and you must also think about the power and magnification of the telescope that will be most useful along with the portability, the mount and the cost.

1. What is the difference between a reflective and a refractive scope? A reflective scope uses mirrors to focus the image and the light while a refractive scope uses curved glass lenses to focus the light and the image. Generally the reflector telescope is better for deep sky viewing and the refractor is better for lunar and planetary viewing. You can also find a compound telescope which uses both glass and mirrors which is better for general viewing.

2. If you think that the greater the power and magnification on a scope, the better it is, you would be mistaken. Generally, the best and clearest images are seen on lower magnification. If you want greater magnification you can always purchase different lenses to supplement your original lens. The main consideration should be the aperture. The aperture is how much light the telescope will let in and be able to focus and this should be one of your main considerations.

3. For those who want to take their telescope with them when they go out into the woods hiking or camping, portability should be an important consideration-especially if you will also be taking a mount and a tripod. If you will simply be setting it up at home, these will not be such important factors.

4. You can choose from one of a few different types of mounts for your telescope-here are two of the most popular: An altazimuth mount allows the scope to move horizontally and vertically and is perfect for beginners. The equatorial mount is favored by professional astronomers and allows the scope to move perpendicularly along the line of the equator to follow the movement of stars and other objects across the sky.

5. Your budget should be one of the most important considerations when choosing a telescope. They range in price anywhere from under fifty dollars to thousands. As a beginner, you will probably want to stay at the lower end of the price spectrum, but consider getting a scope that will allow you to add pieces as you get more experienced and your interest grows.

You can find a lot of information to help you to choose your first telescope online. Information about how scopes work, what all of the scientific jargon means, and also the best places to purchase a scope. Before you make this purchase, educate yourself so that you can feel confident and comfortable that you have made a good choice and you will be able to “focus” your energy on the night sky.

Eriani writes articles about Home and Family. To find more information about telescopes, visit telescopecom.com.

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Many thanks for reading our Reflector Telescope article

Reflector Telescope is a post from: Meade Telescopes