Jacobs Digital

09 480 5903

www.jacobsdigital.co.nz

9 Mokoia Road

Birkenhead, Auckland 0626

OPEN: 9am to 5pm

Monday to Saturday

Choosing your first Telescope - Guide

Posted by Alex Holloway on

It's good that you are reading this guide! Astronomy is fascinating and interesting and everyone should be able to experience the wonder of our solar system, no matter the budget. As you might have guessed by looking around, buying a telescope is very different from buying a Television or a mobile phone. It can be very confusing and in-fact very easy to get confused when looking for a scope. 

I'm going to make this easy for you. The things you need when shopping for a Telescope are:

  • High quality optics

  • A Strong, smooth and stable mount

Sometimes you would also want a scope that's large but don't forget about portability and convenience. You don't want something so heavy you can't move it or set it up easily.  Finding out if the scope has good optics and a good mount can be hard when shopping online. That's why you can always ring and talk to us if you need help in finding a certain piece of information. 

All astronomical telescopes, large or small, are designed to do two things: to brighten and magnify your views of celestial objects. Refractors, reflectors, and compound (catadioptric) telescopes do this in different ways, each with its benefits and drawbacks. We don't be going into them here as for the first time buyer are not that important. 

Aperture

The design of a telescope is not the thing you need to be looking out for though. The biggest and by far the most important factor of a telescope is the aperture - the diameter of its main, light-gathering lens or mirror. (This lens or mirror is called the telescope's objective.) The bigger the aperture, the sharper and brighter the view will be. This of course increases the actual size of the scope so don't go aperture crazy :)

Aperture has nothing to do with magnification directly, that's to do with the eyepieces. Indirectly the telescopes objective determines the "safe" magnification of the scope before the image turns into a dim mess. The telescopes you would be buying as your first scope will come with eyepieces and maybe a Barlow (doubles magnification) so it's not going to be a defining factor when buying your first scope. 

Depending on how good the optics are on the scope and how clear the sky is you can expect to get around x20 to x50 per 2.5cm's (1inch) of Aperture. Most of the time you won't be using the scope anywhere near it's maximum but rather it's lowest as that gives you the sharpest image possible. Don't fall for super high magnification on the box, it's not really going to enable to you see any further without a massive aperture backing it up. 

Focal length

When shopping for Telescopes, you will see focal length listed under it's specifications. Focal length effects field of view. If you want a really high zoom scope, pick a scope with a high Focal length though it will narrow your field of view, picking a scope with a low aperture increases your field of view but you can't use that scope at high power magnification.

The important other half, the mount.

Like I mentioned earlier in the blog, the mount is very important, if not more important then the tube. You want something stable and smooth to track objects and prevent shaking to get the best and most enjoyable viewing experience possible. 

Mounts typically come in two variations: 

Altazimuth & Equatorial - What is the difference?

Above: An example of a Equatorial

An equatorial mount allows the telescope to move in the directions of celestial north-south and east-west. This can be a big help. If you align one axis of an equatorial mount on Polaris (note: Polaris alignment does NOT apply in New Zealand), you can track celestial targets as the Earth turns by moving the telescope around just this one axis. Many equatorial mounts come with an electric motor to do this for you. Motor tracking is especially useful for high-magnification viewing and for showing celestial objects to groups of people. It's also a prerequisite for most through-the-telescope photography.

Above: An example of an Alt-Altazimuth mount
Altazimuth mounts are generally lighter than equatorials, in part because they don't require counterweights to balance the telescope. (I hasten to note, however, that the equatorial "fork" mounts sold with many compound telescopes are relatively lightweight, too; the photo above shows one example.) Dobsonian mounts, in particular, can be very stable and low-cost. They don't however lend themselves to motor operations and you will have to move the scope in 2 directions to track objects. It's much simpler then it sounds, it is effectively just moving the handle. 

Phew, we got there. That is everything you need to know about buying your first scope. Check out our Beginner or Advanced telescope sections to find the entry level scope for you. 

 


Share this post



← Older Post Newer Post →