THE BASICS - What to consider
First things first .
A beginner looking around the market will almost certainly be swayed by glossy adverts on eBay and wonderful looking equipment often displayed in camera stores around Christmas. The temptation to buy a telescope with a promised x700 magnification can be great and when the camera store is doing a very special price its hard not to be tempted. Here's my first bit of advice - DON'T DO IT.
Telescopes are one of the exceptions to the rule that 'you get what you pay for'. Quite often appalling junk is sold with a rather large price tag compared to a quality instrument from a reputable dealer. What looks like a shiny bargain on eBay can very often turn out to be almost unusable, or, if it's a reputable branded item it may have been mishandled by another beginner just like you.
The fact is I have seen too many posts on astronomy bulletin boards where people have paid over the odds, sometimes even more than a new scope for a second-hand item that has problems or have been ripped off buying some no brand scope with terrible optics only to find out they could have bought a quality product from a reputable brand for half the price.
That's not to say every pre-owned scope is a nightmare but use some sound sense and ask the seller questions and assess if they have experience. Most amateur astronomers will look after their equipment and you can find some good bargains but as a general rule it's not advisable for a beginner as they simply lack the knowledge to know what to look for.
Don't imagine that telescopes are like DVD players or other commodity items that will just go when asked with plenty of support and spares. In most cases telescopes of all types require you to devote time and effort to learning how to use them. This is where buying from a reputable dealer will pay dividends in the long run.So - the first rules of buying a scope boil down to;
- Pick a known brand. These include Sky-Watcher, Celestron, Meade, GSO, TAL, and Orion Optics but there are others.
- Buy from a dealer who specialises in astronomy equipment. He will be able to advise you in the purchase and support you afterwards and you may well need that support.
- Finally - avoid eBay and non-specialist shops like the plague you will run a serious risk of ending up with a lemon.
Aperture, Aperture, Aperture
Most astronomers when asked what is the best telescope will promote the view that it's all about aperture (in a nutshell the width of the lens or the main mirror). The larger the aperture the more the telescope (and you) can see. A larger aperture will collect more light and therefore both provide a bigger view and a view which can pick up more detail. I'll talk about magnification later in the article and why you should be dubious about telescopes promising x700 magnification.
Now while the aperture argument is sound enough it does require the application of some common sense. The larger the aperture the larger the telescope becomes, this means the telescope gets longer and heavier. The larger and heavier the telescope becomes the less likely you will be to actually use it and indeed it may be that you have nowhere to store a telescope that could be 6' long and weigh 120lbs. Similarly you may be unable to transport it to a dark sky site if you live in an urban environment with high levels of light pollution.
So you can see aperture is only one part of the equation and I would argue that the real requirement is actually location, location, location. The darker and clearer your skies the more you can see. A very large telescope in a light polluted environment will see less than a smaller telescope that you can take to a dark sky site. You therefore need to balance the aperture against the physical size, storage and transportation issues.
Don't be fooled by collapsible telescopes that will claim you can break the scope down and fit it into the boot of a car. You may well be able to do this but a large Dobsonian style scope may well have a mirror that weighs an awful lot. Some of these can reach over 60lbs which is a lot of weight to carry.
Remember another dictum of astronomy - "the best
telescope is one you will use " - so try not to join 'the biggest one on the block' brigade which can end up with you having an expensive white elephant sat in your garage or spare room that never gets used.
Choosing a telescope
Although the technical aspects of choosing a telescope can be a minefield for beginners it will help you get good advice if you think about the following questions and tell dealers about the answers you arrive at in order to allow them to give you better advice
- Where do you live. If you live on the top floor of a tower block in a city your choice almost certainly needs to take into account portability. If you live in a rural location with a decent sized garden and low light pollution portability may not be an issue.
- Where will you use the scope. Again if you cannot use your telescope from your own location and you buy a monster telescope that's not easily transported it won't be used. So think about possible locations.
- How fit are you. How much kit can you carry/do you want to carry. Any telescope requiring power will require you to carry a power tank (basically a large battery power supply). And all telescopes will involve you carrying other items such as red light torches, extra eyepieces and accessories so bear that in mind.
- Transport. How will you carry the scope. Even if its in a garden shed in your garden if you buy a large telescope you may find its too heavy to lift about OR too difficult to set up. People with bad backs of knees should beware. A lot of this kit is heavy.
- Cost. How much do you want to spend. I would always advise a beginner to not buy more than they can afford to lose. I have seen too many people come into the hobby and buy some kind of monster sized wunderscope only to get bored, find the hobby is too challenging or simply be unable to cope with a giant telescope and end up taking a big loss.
- How much time do you have. This is critical. If you buy a huge complex scope but only have a few hours a week you will get frustrated very quickly when you spend an hour assembling it only to have the clouds arrive or to run out of time. Similarly if you don't have much time to spend you may find that simply finding objects with an all manual telescope and mount takes too long and something that's a bit more automatic may suit you better.
The nice thing about telescopes .
The nice thing about telescopes (at least from a passionate astronomers point of view ) is there are so many of them. So many different types to choose from in fact that it can be very confusing for a beginner. Choice is indeed a curse. In this section I'll talk you through the various types.
Now the first thing to establish is that there are two components to a telescope. The first part is the telescope itself. This is the actual optical part and it's sometimes called an OTA (Optical Tube Assembly). The second part of any telescope is its mounting. Just like telescopes these come in a variety of types with various options. The telescope and the mount can often be mixed and matched so in this section I'll talk only about the OTA ( that's the telescope bit remember). Manufacturers usually package the telescope tube and the mount together along with some eyepieces to use with the telescope but lets look at the various types of telescopes and mounts below.
The types of telescopes discussed in this section are among the most common types available to amateurs. There are many other types available but these tend to be either very expensive or specialised towards specific needs.
APO telescopes are more expensive as their lenses are more complex and more expensive to make. So what's the difference. Achromatic refractors are longer and can exhibit some optical defects such as false colour. This is where the lenses create colour to an object. You can see this in cheap telescopes which produce a definite coloured hue to the image. APO telescopes correct this but at a much higher price. APO types are however highly portable being much shorter than their achromatic cousins. APO telescopes also have a shorter focal ratio which makes them better suited to the needs of astro-imaging.