Buying Guide - How To Choose A Telescope
Just like any other product, you get what you pay for when you are buying a telescope. Don’t let mediocre brands or cheap deals at stores trick you into buying a telescope that gives a low-quality viewing experience.
Ideally, you should buy a powerful telescope that doesn’t dent your bank account but provides a spectacular view of the stars and galaxies spread across the sky. Follow our buying guide to buy the best telescope within your budget.
Magnification or the power of a telescope refers to its ability to enlarge a subject. You get this value when you divide the telescope’s focal length by the eyepiece’s focal length. Generally, a telescope's maximum magnification can be 50 times its aperture, in inches.
Although high magnification can enlarge an object, the high power of your telescope doesn’t guarantee a better viewing experience. Many telescopes with lower magnification offer better and brighter views of nebulae or clusters than high-powered models. Moreover, you will need to search for the right eyepiece that works best with a high-powered telescope.
The aperture is the diameter of either the refractor’s objective lens or the reflector’s objective mirror. The size of the aperture plays a crucial role in selecting the right telescope because its size is directly proportional to the instrument’s ability to gather light. The lighter your telescope can gather, the better image you will see.
The minimum aperture of a useful telescope is at least 130mm for a reflector or 90mm for a refractor with a 1,000mm focal length for each. Such a combination is likely to provide significant light grasp and magnification to get all details of celestial objects.
You should feature at least one eyepiece. However, some sets feature two or three. If it is your first time buying a telescope, a 25-millimeter eyepiece is typical. Like magnification power, a high-power eyepiece does not guarantee the best viewing experience. For instance, you may see a small cluster clearly, but if you use it for viewing a nebula, the eyepiece will only show a part of the object. High- and low-power eyepieces of different field of views are excellent for viewing, and you will need to decide what works best for your needs!
Types of Telescopes
There are two lenses in a refractor telescope, the larger of which is the ‘objective’ on one end. The eyepiece or the ocular through which the observer looks through is at the other end.
Impressive sharpness and contrast
Maybe suitable for Terrestrial viewing as it does not invert the object
Offers protection against dust and humidity
Chromatic aberrations, except on Apochromatic (APO) refractors
Relatively expensive for the aperture size
A reflector telescope uses a concave mirror to gather light at its bottom. This mirror is the ‘primary,’ which focuses the light in various ways, depending on the reflecting scope. Reflectors are most commonly available as Newtonian or Dobsonians.
No chromatic aberrations
Affordable for the aperture size, especially for Dobsonians
Not suitable for terrestrial viewing as the final image is inverted
More vulnerable to humidity and dust
May subject to Coma Aberration (Coma)
While both types of telescopes have pros and cons, refractors offer brighter and better views but are more expensive.
Catadioptrics (Maksutov-Cassegrain & Schmidt-Cassegrain) telescopes
Maksutov-Cassegrain telescopes use a catadioptric design, which means they use both mirrors and lenses. Due to this, they typically are able to fit the same focal length in a more shorter, and compact design.
No thermal degradation and no chromatic aberration
Typically more compact compared to the an equivalent refractors or reflectors
Can be expensive at larger aperture
- Not as good contrast compared to refractors
Telescopes under $100 may be tempting for first-time buyers. However, these models tend to be a waste of your money. High-quality telescopes can range from $200-300 on the starter range to up to $20,000 for the higher ends, depending on their features and capabilities. Make sure you are getting the best deals when buying your first telescope!
Telescopes can weigh between 15 lbs. to over 300 lbs. You will have to break most models into three subsections for transportation: the base or the tripod, the telescope mount, and the optical tube assembly. Consider the size and weight of the telescope that you are willing to carry. Depending on the whether you are using the telescope for visual observation or imaging, you will also need to estimate the total weight. Some arrangements also require counterweights that may add to the total weight of the setup.