Buy a telescope?

Telescopes, also known as star gazers, both open the human eye to the fascinating world of the universe. It is incredible what you can see with a good telescope. No wonder, then, that many are drawn to these wonderful instruments.

Ganymede has an extensive collection of stargazers / telescopes from the most prominent brands. Think of stargazers from:

• Celestron (We are the Dutch importer of this brand)
• William Optics (We are the BeNeLux importer of this brand)
• Orion
• Vixen
• Guan Sheng
• Lumicon
• Baader Planetarium
• 1000 Oaks
• Astrozap
• ADM

In general, the telescopes from our range are directly available from stock. We will do everything we can to deliver your order to your home as soon as possible. We can even personally deliver stargazers to your home.

Telescopes, which is the right telescope for you?

Certainly for the novice astronomer it will not be easy to choose from our wide range. The differences between telescopes can be great. Which one best suits your personal wishes? To help you on your way, here is a brief explanation of the different telescopes that are available. If you have any questions, you can always call us or you can visit our showroom to view the stargazers for themselves and get advice. You’re welcome!

When purchasing stargazers, you should first consider the following:

• Your budget
• Tripod and mount
• Telescope type
• Telescope opening

The guidelines for choosing the right telescope

Stargazers can be quite expensive. Therefore, determine in advance a maximum amount that you want to spend on a telescope. A ready-to-use telescope is recommended for the beginner. You do not need to purchase additional accessories for this, so you can get started with your new hobby right away.

Much more important than is often assumed are the tripod and the mounting of telescopes. After all, the heavier a telescope is, the more solid it must be supported by a stable mount and a stable tripod. Here too there is a choice of several variants. A thick tripod with a sturdy tripod and a heavy mount is ideal. But this is where budget comes into play again: such a solution for stargazers is on the expensive side.

Basically there are three types of telescopes. First of all, there is the Newton system, also called a reflector or mirror telescope. You also have the lens system or refractor. And finally there is the Schmidt-Cassegrain system. Which system you can choose best depends on what you are interested in. A lens system is very suitable if you want to study the moon and the planets. For deep sky objects, a Newton system or even a Schmidt-Cassegrain system is more useful.

The size of the opening of telescopes determines how much you can see. A larger opening catches more light, making the image brighter and allowing you to distinguish more details. A small opening is suitable for viewing the moon and planets; a great one for deep sky objects.

Information about telescopes

Here are a few pros and cons of these systems.

Advantage Newton system:

• Larger opening compared to the lens system.
• No problems with color errors.
• Relatively cheaper because the opening is larger.
• Well suited for deep sky objects such as nebulae.

Disadvantage Newton System:

• Cooling time of the main mirror.
• Collimation of secondary mirror with respect to the main mirror.
• Obstruction in the light road, secondary mirror suspension.
• Less suitable for moon and planets.

Advantage Lenses system:

• Full opening, so no disturbance in the light path.
• Sharp and high-contrast images.
• Little to no cool down time.
• Well suited for moon and planets.

Disadvantage Lenses system:

• Smaller opening compared to the Newton or Schmidt-Cassegrain system.
• Color error in the lens, unless the lens consists of more expensive optics.
• Relatively more expensive due to the smaller openings.
• Less suitable for deep sky objects.

Advantage of the Schmidt-Cassegrain system:

• Relatively compact construction while focal length is long.
• No problems with color errors.
• Many expansion options.
• Smaller versions easy to take with you when traveling.
• Well suited for moon and planets as well as deep sky objects.

Disadvantage of the Schmidt-Cassegrain system:

• Longer cooling time due to closed mirror system.
• Collimation of catch mirror relative to main mirror.
• Obstruction in light away.
• Mirror flop, although that was more of an issue in the old days.

This is only a guide and is by no means a binding summary of the pros and cons. There are also several systems to mention, but from the point of view for beginners, we leave them out of consideration. We try to give you direction with this.

As a beginner, it is important to think about what you want to observe. If you prefer the moon and planets, then the choice of a lens system is the right one. If you prefer deep sky objects, then you prefer a Newton system or even a Schmidt-Cassegrain. There are also gaps in this, but that later.

A number of things are important when purchasing a telescope:

• Budget.
• Tripod and mount.
• Telescope type.
• Telescope aperture.

Budget: Set a budget for yourself but use this as a guide, most beginner telescopes are ready to use. This means that everything is included to start the hobby right away. For example the Celestron AstroMaster or Omni XLT series. Excellent telescopes with which to start the hobby. The Omni XLT is a higher quality overall.

Tripod and Mount: Initially, this is often ignored, while in the further course of the hobby this is one of the most important parts. The larger the opening of a telescope, the heavier the telescope becomes. This means that the tripod and mount must also offer more stability. A too large telescope on a limp tripod and mount is a big annoyance. With every touch the image vibrates and shakes. A thick tripod with sturdy thick tripods and a heavy mount with a smaller telescope is actually the ideal image for the hobbyist. But then the budget comes into play again. Tripod and mount are available in several versions. An azimuth haul, a parallactic. Azimuthal mount does nothing but move left and right and up or down. There are several variants available, the normal manual operation, possibly a computer-controlled one such as the Celestron NexStar SLT, SE or CPC series. There are also the Dobson series telescopes. They are often praised for their value for money. You get a lot of opening, it’s a Newton system telescope, azimuth tripod. However, tracking with such a system is not for beginners. It is excellent for quickly viewing many objects. A parallactic mount also has 2 axes that can be rotated. But a parallactic mount can be adjusted to the latitude of the Earth. For the Netherlands, this ranges from approximately 51 to 53 degrees. 51 degrees for Maastricht and 53 for Groningen. We usually suggest setting it to 52 degrees. You can now follow 1 axis and follow the correct orbit that the moon and planets also follow. In the past, these mounts were equipped with fine movement buttons with which you can keep following the object very nicely. Nowadays these mounts are provided with computer control. The position is determined on the basis of the date, time and coordinates and an alignment on 2 stars ensures that the mount knows where it is. The 40,000+ objects available means that you can see a lot in an evening.

Telescope type: You determine this, by making up for yourself what you want to watch, which mainly interests you. It is also important in what area you live. If you live in or around a big city, there will be a lot of light pollution. As a result, you will hardly be able to perceive many objects. Deep sky objects are usually slightly weaker objects and if there is a lot of light pollution, these are almost impossible objects. Moon and planets are often visible. Then the choice for a lens system can be justified. If you live in the countryside where the light pollution is considerably less, you have many more possibilities to observe. Then the choice on a Newton or Schmidt-Cassegrain may be the right one. Not that a lens viewer does not come into its own, but because the conditions are good, you also want to get more out of a telescope.

Telescope aperture: The larger the opening of a telescope, the more light this telescope receives. Moon and planets are bright objects by themselves and are therefore clearly visible even with a smaller aperture telescope. Again, however, the larger the opening, the brighter the image, and the more detail you can see. If we look at galaxies, a telescope with a larger aperture will provide more resolving power. We then see more stars in the galaxy than with a smaller aperture.

There are also a number of keywords that you will encounter a lot on or when using a telescope.

• Aperture. (D)
• Magnification.
• Focal length.(F)
• Brightness. (f)
• Eyepiece.
• Diagonal.
• Field of view.
• Seeing.

Regarding the aperture we mean the diameter of the lens or main mirror. The larger the opening, the more light enters, the stronger you can enlarge. As a rule of thumb, we stick to 2x the opening is the maximum magnification. For example, if the opening is 102 mm, the maximum magnification is 204x.

Magnification is determined by dividing the focal point of the telescope by the focal point of the eyepiece. For example the focal point of the telescope is 1000 mm and the focal point of the eyepiece is 25 mm, then the magnification is 40x. The magnification also depends on the seeing, if it is poor you can still enlarge very strongly, but you will not get the image or object sharp. Remains blurry.

The focal length of a telescope, is the point where the rays of light converge after being refracted through the lens. This point is called the focal point and the distance between the lens and the focal point is called the focal length which is often shown in mm. You will often encounter the following on a telescope: D = 102 mm F = 1000 mm depending of course on the aperture and focal length.

The brightness is determined by dividing the focal length by the aperture, often indicated as F / 10 or F / 5, this as an example. The lower the number, the brighter or in technical terms, the faster the telescope is.

The eyepiece is a factor in the magnification but also in the quality of the image. It is a bit of dialogue with the telescope’s optics. To explain it easily, I will give the example of a stereo system. You can have a very good amplifier, but if the speakers are nothing you don’t get out of it. And vice versa, the same applies. The speakers are excellent, but the clock radio is the amplifier, it will never be much. In this example, the speakers are the eyepieces. However, purchasing better eyepieces always improves your image. And because the standard eyepiece size is now 31.7 mm (1.25 ”), this is the diameter of the sleeve of the eyepiece which goes in the diagonal, you can always use the eyepiece on another telescope. She used to use 24.5mm (0.96 ”) eyepieces and now the 50.8mm (2”) are on the rise. Most telescope sets come standard with 31.7 mm eyepieces. These are standard eyepieces and in most cases there is still profit to be made here. It is also desirable to have multiple eyepieces so that you can easily search with the lowest magnification because you have a larger field of view. Once you have found the object, you can use a different eyepiece for a higher magnification.

The diagonal is most commonly used with a lens system and Schmidt-Cassegrain system. With these telescopes you look at the back of the telescope and it is desirable that you can look into it from above. The diagonal is 45 degrees and 90 degrees in it. With a Newton system you always look from the side of the telescope and you do not need a diagonal. A telescope set always has a 90 degree diagonal. This puts the image upright, only the left and right are reversed. This has already been adjusted for some telescope sets. However, this happens with a prism and that often results in some loss in your image.

The field of view of a telescope is partly determined by the focal point of a telescope, the longer the focal point, the narrower the field of view. With binoculars, for example, it often reads 123 m / 1000 m. This means that at 1000 meters you have a field of view of 123 meters wide. This is expressed in degrees for binoculars. This is less with stargazing, but because we look over a longer distance we can have a full view of the moon at a reasonable magnification. Here it will be about 1 degree.

Seeing is a notion that as you get further into matter, and speak to other amateurs, is something they always complain about. The seeing, or to throw in a fancy term, Astronomical Vision, is a term used in astronomy for the influence (blur, “twinkling”) of atmospheric disturbances (turbulence) on the vision through telescopes. Visibility is one of the biggest problems in astronomical observations from Earth.

I have tried to tell in my own words about the principles of stargazing, as we at Ganymede teach someone about a telescope. There are many more aspects to take into account or possibilities. There is nothing about astrophotography in it, but this is a subject that a beginner will not go into yet.

It is actually wise to purchase the first telescope from a company or shop where you can see the telescope, and who can actually explain how it works. Get informed and realize what kind of instrument you get. Most telescopes are on a tripod and this is actually larger than can be seen on a photo. Most telescopes are also easy to disassemble and store, often in 3 main parts, tripod, mount and telescope.

There are many models available on the market, of any brand at various toy stores or online bookstores. However, there is a lot, if not a lot of junk in between. Do not be tempted to buy a toy telescope for little money. In that case, buy binoculars so that they can at least explore the sky. With a toy telescope you ruin the interest more than you arouse it. You can see in our store what is cheap, we do not recommend this, but you can also see what you buy something for many nice evenings viewing pleasure.

I hope that with the help of this text you have become a bit wiser in the matter of stargazing, and that you dare to take the step to discover the untold great night sky. We, Jeroen, Peter and Paul, are ready to help you on your way. It takes a lot of patience and perseverance, but you get something special in return.