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How to Choose and Buy a Telescope

This page is dedicated to providing you with a Guide on how to choose a telescope , how to buy a telescope and what is important to arrive at a place where you are able to find the best telescope to buy in the maze of choices that you no doubt have seen on-line or in your local shop, with salesman dancing around you using

foreign jargon and facial expressions enough to make Jim Carrey feel like an amateur.

So lets take a quick tour. Choosing a telescope is a walk in the park ! Additionally get a book on Stargazing for beginners

Don’t search for “this is a good scope” or “the best telescope to buy”. It won’t advertise this.

If you see BIG X type displayed or details describing the strength or powerful type scope, be careful.

Never a free lunch. Its sounds like the stuff to look for but there is a down side.

Increasing the image or object you are viewing requires light to be gathered by the scope over a bigger area and this results in a fainter image. Another problem is that a high powered scope can limit how much of the so called larger picture you can see as a result of the eyepiece manufactured or designed for such a scope.

So often it’s the case that a “lesser” type scope gives you a better experience.

Refractors

     Let’s describe a refractor: It uses 2 lenses. The piece you look through on the one end is the eyepiece and the first lens. On the other side of the scope is the larger one and is referred to as the objective lens. This objective lens is responsible for gathering the light of a distant object and bending it into a single point of focus. Its then that the eyepiece lens takes this point of focused light and enlarges it for the retina to observe. The eyepiece can be compared to looking at a small object through a magnifying glass. That simple. Got it?

Beginner mistakes!

A simple mistake newbies to scope viewing make, is to believe that a telescope magnifies objects which is wrong, well not entirely. The primary and main function of a telescope is to gather much more light than the observer’s eye alone could gather. So the more light the objective lens in the refractor scope can gather, the more detail can be seen by the observer. This detail magnified by the eyepiece for the observer to see.

Reflector

Let’s describe a reflector: Here the telescope uses two mirrors instead of two lenses. Light from an object enters the telescope pipe or tube and is reflected off a curved mirror at the end or opposite side of the tube. A second, small, flat mirror in the middle of the tube reflects this image to the eyepiece.

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There are many ways the primary lens can focus the light and how it is done determines the type of reflecting scopes.

Advantage of a reflector

It pick up chromatic aberration (a rainbow effect seen around some objects viewed with a refractor telescope). Mirrors used to pick up light don’t have this problem.

Disadvantage of a reflector or mirrors type telescope

Some light is always lost in the reflection when mirrors are used. To gauge this better, a good telescope can gather around 90% of the incoming light. Further the mirror might not be a perfect curve, so an image will not be focused or reflected to a perfect point resulting in that a point could be seen as either a line or a cross. Lastly a mirror needs to be realigned every so often and also cleaned.

Aperture

Aperture size is THE BIG CONSIDERATION!! The strength, power, or “BIG TELESCOPE” you are looking for, will be determined by this factor. The aperture of a scope refers to the diameter of both the refractor and reflector telescope lenses and in particular the objective lenses in both of them. So in summary it’s all about the light your telescope can gather. You determine this strength, ability of the telescope by the aperture size of the telescope. The telescope’s ability to gather light is directly proportional to its aperture. At this stage you’re thinking, well I’ll just go out and buy the “largest” one I can find.

Let me make an analogy.

If you go camping and need a tent, and you buy one with all the bells and whistles, it will be a large tent, full with verandas, multiple rooms and separate compartments, even a kitchen section, yes a TV section too and remember the washing compartment too and oh yes, don’t forget all the add-ons like chairs, umbrellas, ground sheets, extra element protection sheets etc., the equipment and all the accessories that can go with camping out…

BUT ………….the truth is that when you got it all, how often will you go camping?

To load all the paraphernalia is cumbersome and you will need more than just your car.

The effort to do the packing is hell and the bottom line is you will do this a lot less often, than if you fitted yourself out with the basics knowing what you intend to do and will need on such an occasion.

Be careful of Large telescopes

Large telescopes could mean you don’t GET OUT and do what you intended initially when you bought your telescope. Make sense? Hence the idea maybe to have more viewing time whilst enjoying a glass of wine.

Typically, 2.4 inch or 60mm and 3.1 inch or 80mm refractors and 4.5 inch and 6 inch reflectors are popular choices for the most amateur telescopeurs ..lol.

Focal Ratio

What’s this? No its not the difference between your eyesight when you were 10 and your great gran at 105. When you divide the aperture size into its focal length you get the focal ratio. The focal length is measured from the main lens (or mirror) to where the light converges to focus. As an example, a scope with an aperture of 4.5 inches and focal length of 45 inches, will have a focal ratio of f10.

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While a higher focal ratio does not always mean a higher quality image, it often means as good an image for similar cost, however, a higher focal ratio with the same size aperture means a longer scope, which can translate into transport problems. Too big a telescope to transport in your car, yes the tent story remember.

Telescope Mount

Very important to steady your telescope.

Was this a part of your consideration yet? Probably not. Most people didn’t even know about this.

This is an object used to keep your scope steady. Ever looked through a rifle telescope?

If you don’t lay it down on a fixed surface to steady it, it’s very hard to look at the object in the viewer, as the object your’e viewing will slip in and out of sight.

Ever tried to look through a pair of binoculars whilst driving in a car? Not fun at all.

To hold the scope steady is important if not critical. A near impossible feat to observe a distant object through a telescope if your telescope isn’t completely still. The problem is amplified exponentially, when looking to the skies, as a result of the greater distances involved.

Mounts

There are basically 2 types of mounts, altazimuth & equatorial.

Altazimuth is similar to a camera tripod. It allows the telescope to move up and down (altitude) and back and forth (azimuth).

Equatorial is designed to track the movement of the object you are viewing in the sky. Top class equatorials have a motor drive to track the rotation of the earth, keeping the object in your field of view. Equatorial mounts can also be equipped with a small computer, which will aim the scope automatically.

This feature has revolutionized the time spent viewing and having effective time behind the telescope. This has pretty much done what digital photography has done for your amateur photographer.

Where people took a few images on holiday in the past, they now can take hundreds of pictures without cost and later discard what they don’t want.

Eyepiece

What’s important here?

It’s the most important accessory for your telescope.

Howcome?

Cheaper telescopes are fitted with basic or low quality eyepieces. So a simple upgrade to a better eyepiece is the simplest way to improve your telescope’s performance. Your new scope should have at least 1 eyepiece, and often 2 or 3. An eyepiece will be rated in millimetres, smaller numbers indicating higher magnification. A 25 mm eyepiece is common and appropriate for most beginners.

Remember that higher and lower strength eyepieces each have their place in observing. Having a high end eyepiece isn’t a one fits all uses. but don’t worry too much right now about this.

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Keep it in mind and its an accessory you can add as you get into this hobby.

A higher magnification eyepiece provides more detail, but could be harder to keep an object in view and then when using a motorized stand or mount it will solve this. Higher mag eyepiece also requires the telescope to gather more light to provide a clearer image.

Remember the number on the eyepiece is the focal length of that eyepiece. It doesn’t indicate strength or power of the eye piece.

The same eyepiece can be used on many telescopes and the magnification in every case dependent on the focal length of that telescope.

How much will my telescope cost?

Pay peanuts, get monkeys. The golden rule applies here too with a telescope.

You get what you pay for. Where you buy from however can save you the money you are looking for. Don’t let the cost deter you from buying the better scope within parameters of your budget.

This site is mostly about being able to provide better prices, through on-line options with different manufacturers, as overheads and everyday business costs are reduced because of the nature of on-line business. Lower overheads, lower prices.

The logic here is to buy the best you have in your budget. Buy wisely understanding what exactly you desire, realising that your goal in terms of what you are buying will change in future, well chances are very good if this hobby gets into your blood. Anticipate this without going overboard. Most first time buyers don’t need an expensive telescope.

TIPS:

Ask a friend to use their telescope. Join or visit an astronomy club in your area. Feel out numerous telescopes and ask questions to many experienced telescope owners. Beware of advice from those who think they know it all with a few months experience.

Make a short list of what you would like to look at. Write it down. Deep space , moon viewing or cluster gazing will require different aspects you will need to include in your purchase to make it a reality come true. There is a telescope accessories section in the menu that shows a large range of add ons or additional equipment and how it relates to your telescopes for beginners enquiry.

In Closing

I hope this has been helpful. I will be expanding on simplicity in the future to make this a fun experience without the “labour pains” .

Happy choosing, buying , viewing and discovering. Go to the selection of telescopes sale to see a wide selection of telescopes and related items.

Make my day and post some pics in the Public Images section and add your comments.

I hope you are clearer now on how to buy a telescope and you can take the next step.

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