How To Buy a Telescope: Part 1

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The Story of Little Jimmy

It’s just another trip to S-Mart, the local big box store, as Jimmy and his mother patiently wait for the glass gate to slide open.  A gust of air howls, carrying with it the aroma of floor wax and commerce. At first, Jimmy thought the toy aisle offered nothing new.  That’s when he laid eyes on the StarBlaster 5000…a rectangular box…proudly boasting its abilities:

  • Magnifies 500x
  • Simple and easy to set up
  • Tonight the universe is yours to behold!

 

Little Jimmy can’t help but gawk at the graphics…a purple galaxy…an odd planet adorned with bands of gaseous gold…jagged craters…like open mouths…screaming in eternal terror. Little Jimmy places the Starblaster 5000 underneath his arm and walks past the newly stocked action figures.

After dinner, he into the box, and then throws the instructions over his shoulder.

Ten minutes later—the Starblaster 5000 is at his command! He pockets the provided 25mm eye piece, then hauls the ‘scope outside.

Little Jimmy looks up and admires the gems of the night radiating their brilliance.

Little Jimmy cranks his neck underneath the telescope, but cant see a damn thing! 15 minutes later, he centers the Moon in the Starblaster 5000’s field of view.

Little Jimmy takes a step back admiring his work. Arms crossed behind back, he peeks into the eyepiece. A sweet summer’s breeze rolls by and shakes the Starblaster 5000.

Plastic screws fall to grass. He sighs and the soft breath that escapes out of his mouth causes the Starblaster 5000 to spin.

Little Jimmy throws the telescope inside his closet, while using his free hand to rub the back of his neck.

 

Get On With It

 

Wait. Are you still here? Great!

Unfortunately, the story I described above happens every year during someone’s birthday or holiday. Lured and tricked by fancy marketing, it’s extremely easy to waste your money on a toy—or worse—a lie. There are plenty of telescopes that are on sale right now claiming to do impossible astronomical feats.

Cheap telescopes exaggerate their power capability. A simple mathematical formula is all that is needed to accurately calculate a telescope’s magnification.

Divide the focal length of the telescope (in millimeters) by the eyepiece’s focal length (in millimeters).

For example:

600/25=24x

 

Simple as that. The Starblaster 5000 greatly inflated its power by claiming it can produce 500x. In fact. in order to produce those kinds of magnifications, you would need a telescope with a focal length of 12,500mm (using a 25mm eyepiece).

12,500/25=500x

 

A ‘scope like that will never be discovered down the toy aisle at your local department store. Don’t bother looking.

Also: don’t fall in love with pretty pictures on the box, or images claiming to be taken with the telescope in question. The colors of celestial objects witnessed through an eyepiece come in ghostly wisps of silver. You’ll have to be content with that and bask in the knowledge of what you’re looking at.

Celestial objects are diluted by an unimaginable expanse of black. Any color that remains is unable to trigger the cones in our eyes, which means the color would not be perceptible.

 

So, What Should I get?

 

What telescope is right for you? Is that what you’re asking?

Sorry. I’m unable to tell you. All I can offer is my experience, and hopefully you’re able to use it to make an educated purchase. Not just for a product, but an instrument that will grant you the ability to peer deeper into the dark.

So.

Who are you?

Are you someone who has the funds of some kind of super villain? If that’s the case feel, then free to buy out an entire catalog and try them all. Everybody’s situation is unique, thus the telescope should be tailored to their needs.

Are you a city dweller? Then perhaps a small, lightweight refractor is what you need to haul from place to place.

Do you reside in the woods? Then perhaps you can use a large aperture monster that can be rolled out of a garage.

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Refractor

This is the classic picture everyone has emblazoned in their mind of what a telescope looks like—the refractor. A tube with a lens at the front, which is designed to bend or ‘refract’ the incoming light.

Simple and elegant in its design, that’s why this is the breed of telescope misrepresented in stores that sell it next to cat litter.

The lens of a poorly constructed refractor will exhibit something called ‘chromatic aberration’.

That’s a fancy way of saying if the refractor is aimed at the Moon (or any bright object in the sky), a disgusting purple halo will manifest around the object. However, the more exotic refractors made by companies such as Takahashi or Astro-Physics, are highly corrected to remove many optical symptoms.

The shorter the focal length, the more pronounced the effect will become.

 

image

The other breed of telescope is called a reflector, and it utilizes a mirror instead of a traditional lens. Mirrors don’t produce chromatic aberration and they’re cheaper to make.

Due to the time it takes to align the secondary-mirror (and its bulky construction), reflectors get zero points for mobility.

If you have a few thousand dollars you don’t mind parting with, then perhaps you’d like to order one of these mirrored behemoths.

image

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Catadioptric

The last breed is more like a chimaera—a mix between a refractor and reflector. A lens sits at the front of the tube and a mirror is also placed toward the back of the tube, which is able to ‘fold the light path’ into a tighter package without sacrificing power.

No telescope of comparable size can match a catadioptric in this regard. A 4.5 inch  catadioptric (with a focal length of 1300mm) is about half the size of a 700mm refractor.

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Large refractors can be unwieldy.

Catadioptric telescopes will always be compact by comparison, but they’re heavier.  If you desire power in a compact design, then a catadioptric telescope will serve you well.

The Choice Is Yours


It doesn’t matter what you get if the telescope trembles with every soft breeze or if the plastic breaks in your hands.

The importance of a stable mount cant be stressed enough. No matter which telescope you choose, the first priority is to make sure the mount is viable.

Otherwise you may end up like Little Jimmy, discouraged to only look up when taking out the trash.

Related reading: How To Buy A Telescope -Part 2-

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About FlyTrapMan (200 Articles)
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2 Comments on How To Buy a Telescope: Part 1

  1. Hi,

    So I have a quick question. I am beginning to become very interested in astronomy, and have been looking at buying a decent telescope. I am currently a student in college in NC and would like to buy something that will last a few years or longer. I have found a few models that I like after reading some reviews and such. I saw on http://www.besttelescopehq.com that the Orion SkyQuest XT8 Classic Dobsonian Telescope is a decent telescope and seemed to fit what I was looking for. My question lol. Do you have any experience with this telescope or could you recommend anything similar that I may could consider.

    Thanks!

    Liked by 1 person

    • Thanks for commenting!

      I have no experience using the Orion SkyQuest XT8. I looked over the stats and the telescope seems solid. Keep in mind: reflector telescopes need to be manually collimated. Will this telescope last? Well…I can’t comment on the computer tracking system, however, if you take care of the telescope, then it will last much longer than a few years. Just don’t keep the telescope in a car for long periods of time. Otherwise rust will develop on any exposed metal.

      Do you have a permanent place where the telescope can be stored and used? It will be difficult to carry the telescope around. If you have to travel from place to place in order to use your telescope, then getting something smaller (like a short tube refractor or catadioptric) would benefit you in most situations.

      I’m not sure if you’re concerned about portability, because it will be difficult to carry around a hefty Dobsobian reflector.

      You can also get a high quality cheap binocular if portability is an issue. Personally, I use this one: http://www.telescope.com/Binoculars/Astronomy-Binoculars/Orion-Scenix-10×50-Wide-Angle-Binoculars/pc/-1/c/5/sc/72/p/9333.uts

      If you don’t own a binocular, then I highly suggest purchasing one. It will be very useful once you acquire a telescope.

      Let me know if you have any further questions!

      Like

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