Astronomy

Astronomy a Shoppers Guide to Telescopes for Beginners



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Knowing which telescope is best suited for a beginner can be quite a dilemma. The vast array of answers to the various questions one will have, can often be convoluted. This is due to a host of beginners seeking information in the wrong areas such as social discussions forums. While most people do mean well, many steer novice astronomers in the wrong direction. First and foremost, you need to know your true requirements and fit the budget with your needs as well as your budget. Not really knowing how if astronomy is really your thing until you start, one would be foolish to outlay too much money at first.

Most often, newcomers to astronomy are steered towards an 8-inch Dobsonian scope. For adults this is a good choice. But one can get just as good results from a smaller instrument such as a 4.5-inch Newtonian. And a 90mm refractor will be well appreciated by beginners too. One needs to realize that bigger is not always better. Many professional astronomers will tell you that smaller telescopes have a plethora of benefits which many people are totally unaware of. Portability is one of the benefits of smaller telescopes and can give you an amazing view of the world above.

They can be placed in the boot of your car, backpack and so forth. You need to weigh up where and how you intend to use the telescope and realistically how far your budget will stretch. What technical requirements do you desire? Are you after specific things such as sophistication, weight, control etc? Common sense will tell you that your budget will basically dictate just how sophisticated your telescope will be. Your telescope will be gathering light and magnify the heavenly views. Therefore the functions of all telescopes is basically the same.

Designs vary yes, but the principal function is still there. Mounts vary as well and one can purchase a simple of sophisticated model. Stability is what you should be looking for more than design. Start out with the basics and you can expand on your telescope system over a period of time. You could start out with a 200mm Newtonian like the author did and once you decide to step into the world of astrophotography you could then think about something such as the highly popular SW600. These are fitted with a basic motor drive option. If you are wishing to get into astronomy right now instead of saving for a more sophisticated telescope an SW680 is a great option.

Down the track you could think about purchasing a EQ5 mount, tube rings, mounting plate and motor drive kit. But first weigh up what you really want from your telescope prior to rushing out the door. How will it be used? Will it be used on the ground, mounted on a table outdoors etc? For basic stargazing a Spotting Scope would be ideal for a beginner. If you are hoping to view more distant objects you will need a little more aperture and strength. More so in low light, dusk and twilight hours. If you wish to view the moon or planets, the 90mm refractor is perfect for doing so.

If you just want something for viewing the sky at night. The Dobsonian will give you a basic up-down-left to right movement. Want more than that? Well that’s when a more complex mount is needed. Opt for a basic equatorial or a sophisticated GOTO system. These are very easy to use. If you are purchasing for a young child, the Dobsonian is the top choice. These are well suited for children 8 and over. Basic up and down, left and right targeting is so easy with an affordable SW580. Because the earth consistently spins, an equatorially mounted telescope is great as well.

This is ideal for those wishing to educate themselves in various ways. The equatorially mounted telescopes move in arcs. Because earth is spherical this type of telescope is educational while providing amazing views. You will be able to keep objects in focus so much easier. Now how far do you wish to see? This is where the magnifying strength comes into the equation. A smaller telescope will give a dimmer less clear view than a larger instrument due to the fact that it will have less photons (light).  You may wish to invest in a refracting telescope. These give the user sharp images, portability and all-purpose flexibility and that’s definitely a plus.

For those new to astronomy, refraction is basically the bending of light. This is the result of the light’s passage from what is called a medium ( such as air) to another medium which in the case of a telescope is the glass. Refracting telescopes are equipped with specially made lens which have a curved surface. When the light passes from the air to the glass and then back to the air, its path is bent towards the optical axis of the telescope’s lens. When this is type of telescope if of good quality, the light is brought into focus well. Good quality apochromatic or achromatic refractors give you an advantage over a host of other telescope designs.

Why? Because the refractors have a completely clear aperture. With no central obstructions whatsoever, light is scattered to all areas. The consequences of this is that the contrasts are much better. Refractors are deemed the premier instruments when speaking of astronomy. Besides, they’re easier to maintain and don’t need recoating. The optical tube assembly does not require collimation and that’s another plus. The lens is fixed to the inside of the tube and does not usually become misaligned. On the other hand, you may be interested in the reflector type of telescope. But these do have their disadvantages.

The secondary mirror causes what is called ‘central obstruction’. What this does is cause a scattering of light and loss of contrast to the viewed image. Manufacturers have produced what they call a planetary Newtonian. These have smaller central obstructions. But they are all said to suffer from ‘coma’ which is a defect which has the stars at the edge of your field of view looking like comets. The smaller the focal ratio is the larger the coma is. Mirrors may also need maintenance down the track as well. Reflectors are very sensitive to being transported, jostled and so forth.

Prior to purchasing a telescope, do your research. Read up about the manufacturers and read reviews about all types of telescopes. Become familiar with all terms used to evaluate telescopes. Read astronomy magazines and know your needs. Ignore the touts about magnification. All you have to do to alter the magnification of a telescope is to change the eye-piece. To calculate a telescope’s maximum magnification ability is to multiply the size of the lens or mirror in inches by 50. Therefore if you have a 4 inch telescope, it can be used with eyepieces which provide approximately 200x.

Try the telescope before you buy. The easiest way to do this is to get in contact with an astronomy club and ask when they are having an open day or public observing session. Ask questions and learn first hand about the most favoured telescopes. Visit a local planetarium if there are no clubs near you. Look for a reputable telescope dealer who has been in business for a god number of years. A reputable dealer will ask you questions about your needs, budget, level of expertise and so forth. Skip the department store and catalogue showrooms as they will attempt to sell you more than you truly need.

As you can see, your options are many depending on your needs. Don’t rush in, weigh up all the pros and cons first. Stick to your budget and put a little money aside each week to add to your system once you feel more confident. Don’t purchase telescopes from sales as they are usually just junk. Do brand comparisons and then make your selection.

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