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Jacob's Photo & Digital
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Birkenhead
Auckland 0626

Feeling starstruck? Want to start gazing at the stars but don't know where to start?

This guide will help you understand telescopes so you can buy the one that suits your needs.

 

To understand what to buy, you need to know a little about them. The main specification being:

Aperture: A Telescope's Most Important Specification

The most important aspect of any telescope is its aperture, the diameter of its main optical component, which can be either a lens or a mirror. A scope's aperture determines both its light-gathering ability (how bright the image appears) and its resolving power (how sharp the image appears). When learning how to choose a telescope, knowing all you can about the aperture is crucial to your ability to see the night sky.

What does this mean? The bigger the aperture the better. With a 6-inch telescope you can discern craters on the moon as small as about a mile across — half the size of those visible in a 3-inch scope (under the same conditions using the same magnification). The advantage of a larger aperture becomes more apparent when looking towards a distant galaxy on a moonless night. Because the surface area of a 6-inch mirror is four times greater than that of a 3-inch mirror, it collects four times as much light, meaning the galaxy would appear four times brighter. (Astronomically speaking, that's 1.5 magnitudes brighter.)

Seen above, Jupiter under ideal viewing conditions (Left: 2" aperture, Right: 4" aperture right).

Magnification

Magnification is determined by your telescope’s focal length and your eyepiece. The bigger, the better HOWEVER You can always upgrade to an eyepiece with higher magnification later. This is why it's not very important and you should be looking at the aperture. We sell lots of different eyepieces to allow you to get more, or less magnification depending on what you want to view.

Looking beyond aperture

Okay, so a telescope's ability to gather light is paramount. Should you, then, look for the largest telescope you can possibly afford? Maybe, but not necessarily. You also need to consider portability and ease of use. After all, what good is a telescope you don't use?

Before you consider specific telescope options, ask yourself where you will want to use your new telescope. If the answer is in the backyard, then a great big telescope might be perfect. But if you want to take your telescope to dark-sky locations for better viewing away from city lights, size and weight become important factors. If you plan on taking your scope on camping trips, it will be sharing space in your car with other gear.

You’ll also want to think about the complexity of your telescope setup. If you want to be able to take a quick peek at the night sky, choose a simple telescope that sets up in just a few minutes. If you choose a bulky, complicated telescope, it will probably spend more time in the garage and you’ll spend less time under the stars.

Optical Styles

This is a complex subject so I'm going to make it short. Choosing an optical design should not influence you more than getting a good aperture. Each design has pros and cons.

Refractor

This is the telescope shape you’re probably most familiar with. The main optical element is a lens on the front which refracts light directly onto a mirror at the back and into the eyepiece.

Pros

  • Simple design, easy to use
  • Works for objects on earth
  • Sealed tube protects optics
  • Sturdy and no maintenance

Cons:

  • Not ideal for faint objects
  • Can be heavy and bulky
  • Less value than reflector

Reflector

As the name suggests, this design has a mirror at the end of its tube which gathers light before sending it through another mirror into the eyepiece.

Pros:

  • Great for viewing faint objects.
  • Very high image quality.
  • More value than refractors.
  • Compact and light weight.

Cons:

  • Open tube can collect dust.
  • Requires some maintenance.
  • Doesn't work for earth objects.

Compound

This type of telescope is also called catadioptric or "Schmidt-Cassegrain" telescope. It features two mirrors (one in the back and one in the front) plus a lens.

Pros:

  • Great for viewing faint objects
  • Works for objects on earth
  • Sealed tube protects optics
  • Great for astrophotography

Cons:

  • Usually more expensive
  • Large, bulky appearance
  • Second mirror reduces brightness

Mounts and how the move

Altazimuth mounts (AZ)

Altazimuth (from altitude + azimuth) is the simplest telescope mount design as it pivots on two axes (see left) relative to the ground. Modern telescopes with altazimuth mounts often have computer control or a manual fine adjustment knob to precisely track objects. It's all about giving you maximum control over how the telescope moves.

Equatorial mounts (EQ)

In simple terms, equatorial mounts are designed to follow the rotating night sky as the Earth turns. While you need to adjust two directions with an altazimuth mount, you align the equatorial mount to the Earth's axis (pole to pole). This way you can slowly turn it and objects in the sky will appear to stand still in your field of view. It's definitely a bit harder to use but for astrophotography this type of telescope mount is the best choice if it's motorised.

Astrophotography

This is a complex subject. All the telescopes we sell can be mounted with a camera however don't expect to be taking jaw dropping results without spending serious amounts of money on a really good tracking mount.

Sky is the limit for astrophotography, you can start by using your smartphone and adapter however to get serious you'll need

A motorised equatorial mount Astrophotography tube (OTA) DSLR, mirrorless or astrophtography CCD Camera (Purpose Built) Telescope Tube Connections for your Camera

This is a basic minimum. From there you can add autoguiders, focal reducers, coma correctors, filters and more. It gets very expensive but is highly rewarding and enjoyable.

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