Buying telescopes can feel like a big step, especially if you’re not sure what all those terms mean. So, to help you understand what to look for in a quality telescope, read below for all of the details.
We carry a small range (4-6 models) here at Coast Photo, it is always best to get in touch and we can let you know if the model you are keen on is in stock! And if not, – we can arrange this pretty quickly provided the suppliers have stock available.
Feel free to reach out and we will give you a hand. 🙂
We live in a rather crazy and fast paced world. And it can be difficult to take some time to unwind and do something contemplative, It just goes almost without saying that the universe is a mysterious and remarkable place. But there is much more to it, there is also a feeling that comes along with viewing – it is a feeling of awe and wonder.
There is something very significant about seeing the universe.
You cannot help but think about the nature and mystery of life when looking up at the night sky. There is something about astronomy that evokes a philosophical train of thought.
You may have felt this before when looking up at the stars. 🙂
Telescopes work by gathering light — some do this using mirrors (reflecting telescopes), and others use lenses (refracting telescopes). The light that is gathered by the telescope forms an image which is then magnified using an eyepiece that you look through.
The more light a telescope can gather, the brighter the image formed and the more detail you will see. The power of a telescope is determined by how much light it can collect — not by how much it can magnify!
Most of our telescopes will have a low magnification eyepiece to allow you to search for an object maybe an animal or a boat on the ocean, once you have found the object you then have a second eyepiece to increase the magnification to get closer and see more detail if you would like to.
For Astronomy most of these dual purpose telescopes will give you great views of the Moon and the major Planets.
GoTo telescopes can access and track thousands of stars or objects with just a simple touch of a button.
The beauty of having a GoTo (Computerized Navigation) Telescope, is that you will spend less time hunting for objects and more time viewing!
These features have made these scopes are very desirable with many people, & especially astro-photographers.
is that you can keep studying the object in your eyepiece and not worry if others bump into it, or the telescopes is accidentally moved.
These take a lot of the work out of your observing sessions by finding and tracking celestial objects of all kinds.
A telescopes aperture is the diameter of the main lens or mirror (slightly less than the outer diameter of the main tube). Its purpose is to collect light and is the most important technical consideration.
The greater the aperture, the more light collected, and this combined with the eye piece used determines the magnification and clarity of the object you are viewing.
Light gathering power is proportional to the area of the lens or mirror, which depends on the square of the radius, so it increases rapidly with increased aperture. For example, a 200 mm telescope does not gather twice as much light as a 100 mm telescope — it gathers about four times as much.
Aperture is very important for visual observation (i.e. using your eye and an eyepiece) because it determines what you can see.
The telescopes magnification is important but not as important as aperture.
How to calculate magnification: You can calculate magnification on your own by dividing the focal length of the telescope by the focal length of the eye piece. Both numbers should be readily available from the manufacturer.
A telescopes magnification can be changed by the eye piece used. Maximum useful magnification is approx. 2 times the aperture in mm, for example a 102 mm aperture telescope can usefully magnify up to 204 times.
Using an eyepiece which gives a magnification beyond that limit is normally of little use. The amount of light that a telescope can gather depends on size of the aperture and the more light that can be gathered, the better the resolution.
Highest Useful Magnification: The maximum practical magnification is known to be calculated as 60x per inch of aperture. (Or 2.4 of aperture in millimeters.) That’s basically dictated by the properties of light.
Trying to use an eye piece to magnify more than this will result in a narrow field of view and unclear image. Less magnification is often preferred as you get a wider field of view and increased clarity.
An idea of magnification to the actual distance:
As an example: Consider Jupiter to be at an average distance of 630,000,000 km from Earth, Magnification by 60 makes it look 60 times closer.
So, with the use of that 60x magnification: It looks as if you are 10,500,000km away from Jupiter (not closer) ; Opposed to the current distance of 630,000,000 km.
What will I see?
Astronomically, you can see the Moon, the Sun if correctly filtered, all of the planets except perhaps Pluto, some surface details on Mars, Jupiter and Saturn, multiple stars, globular and open clusters, bright nebulae, galaxies and nearby galaxy clusters.
Will I see objects like I would see in a photograph?
Yes and no. Bright objects like the Moon, some planets and some star clusters will show colours and features just like photographs, but faint objects are more difficult.
The eye is not sensitive enough to detect colour at low light levels so even bright nebulae appear as shades of gray in small telescopes.
Colour films and digital images can be exposed long enough to collect light across the visible spectrum so photographs show colours than you don’t see visually.
Will the image be the right way up, or upside down?
Depending on the type of telescope, the image you see may be either upside-down, backwards, rotated, or normally oriented.
For most astronomical observing, it makes little difference if an object is seen upside-down or at an otherwise odd angle (after all, there’s no “right side up” in space!).
However, for terrestrial viewing you certainly don’t want to see everything upside-down. And when stargazing, it’s hard to compare what you’re seeing to your star chart if the image is inverted or flopped.
Different telescopes produce different image orientations:
One of the most common types of telescopes, is a Refractor. At the front of the telescope, a lens known as an “aperture” directs light through the scope to a mirror into the eyepiece. Because this style of telescope doesn’t invert the image before it reaches the eye, users can view objects both in the sky and on Earth.
This is the oldest type of telescope and it is what we think of when we think “telescope”. It has a long tube with a big lens on one end and an eyepiece on the other. If you want good value and a good viewing experience you may want to consider getting this type of telescope.
Refractor telescopes can also be stunningly effective for serious astronomical viewing and you can spend quite a lot of money to get an observatory quality telescope with all the accessories and super steady mounts. This kind of telescope is for very serious amateurs or for astronomy groups, clubs, even schools and universities (or serious amateurs) This kind of larger refractor can yield stunning results when it comes to viewing and when it comes to astro photography.
However, to view very faint objects in the sky, a reflector is best suited.
Reflector telescopes don’t use a lens; instead, their two mirrors gather and direct the light from the night sky. This process inverts the image, which makes viewing objects on Earth difficult. However, this method helps focus and provide additional clarity to objects that would appear faint in a refractor telescope.
No lens means that dust and dirt may get into the internal components. Users should plan to clean the telescope regularly and store it in an appropriate location.
Because you can get large apertures out of the mirrors and the lengthened focal length due to the light being reflected from the primary to secondary mirrors and then to the eyepiece, reflectors are ideal for seeing the deep-sky objects that refractors often miss, such as galaxies and nebulae.
A Reflector (or Newtonian) is hard to beat for astronomy viewing and is perfect if you don’t need to view land based subjects, if you don’t require much portability and do not plan on doing much photography.
The Dobsonian or Dob telescopes are optically similar to reflector telescopes and offer the most cost effective way to start and develop your astronomy hobby. Where the Dobsonian is different is in the mounting system that allows you to find and track objects.
A Dobsonian base is elegantly simple, there are no knobs, levers, switches, gears, handles, dials, or anything complicated required to operate the telescope. Everything is moved by hand and in an altitude-azimuth (up-down/left-right) configuration making it simple and intuitive to use.
These are popular among amateur astronomers due to it’s extra large aperture and low price. Perfect for budding astronomers as they’re powerful, easy to use, and very affordable providing the biggest aperture at a good price.
They have larger apertures, which mean that they provide excellent viewing of faint deep sky objects including remote galaxies, nebulae, and star clusters. They’re also low in optical irregularities and deliver bright images. They’re also much simpler to set up, transport, and operate.
Dobsonian telescopes are less suitable for astrophotography. Unlike refracting telescopes, these are generally not suited for terrestrial viewing, and because the tube is open to air, it requires a bit more care and maintenance.
Cassegrain telescopes are catadioptric systems, meaning that they use a combination of lenses and specifically shaped mirrors to form an image. Their designs take advantage of a folded optical path that reduces the size of the telescope, making them easier to produce and transport. The combination of lenses and mirrors also mean that the telescopes have an overall greater degree of error correction with a wider abberation-free field of view.
The two most popular Cassegrain designs are the Maksutov Cassegrain and Schmidt-Cassegrain telescopes. Without going into too much detail, the Maksutov Cassegrain telescope uses a corrector lens and spherical mirrors to correct off-axis aberrations and chromatic aberration. On the other hand, the Schmidt-Cassegrain telescope uses a spherical primary mirror and a Schmidt corrector plate to correct for spherical aberrations.
Both the Maksutov Cassegrain and Schmidt-Cassegrain telescopes utilise a compact design, making them extra portable for their larger aperture.
They are suitable for lunar, planetary, and deep space observation, and are especially excellent for astrophotography as they have the best near focus capability among all the types of telescopes. Cassegrain telescopes are also durable due to their closed tube design and suited for land-viewing, making them one of the best quality and versatile telescopes available in the market.
For the observer who wants a little of everything, from deep-sky to planetary viewing and imaging / photography, plus portability, a Cassegrain is an excellent choice. It is the one telescope that can be used for almost any application and as such is one one of the most popular telescopes on the market today.
The mounting system refers to the way the telescope tracks moving objects. An ‘Alt-Azimuth’ or ‘AZ Mount’ is the best choice for a general purpose telescope as it moves the telescope in a simple left-right and up-down motion.
Barlow Lenses of 2x or 3x are popular because they allow you to double or triple the magnification of each of your eyepieces without affecting the eye relief or your ability to focus and resolve the images that might occur if you used a shorter focal length eyepiece to achieve a similar magnification.
If you have a single high-quality eyepiece, picking up a quality Barlow lens will be less expensive, while giving you two magnifications from one eyepiece.