How To Choose The Best Telescope For You

Which Telescope Should I Buy?

Choosing the right telescope can be difficult for a beginner (and even an expert!). With various designs, accessories, and specs it can be hard to keep track of everything. That’s why here at Astraeus Optics we want to make it simple for you and inform you in the best way possible.

Our goal is to help guide you down the right path to the exact telescope that matches your needs. Whether you are interested in astrophotography, admiring planetary bodies in our own solar system, or peering deep into the universe and into scattered nebulae, you need the right telescope and accessories to do so. Here we will give you a simple overview of the most common telescopes designs that are made as well as their pros and cons to get you started. Then we'll finish off with two key characteristics of any telescope and what you should consider before taking one home for yourself!

Refractor (Dioptric) Telescopes

Refractor telescopes, also known as dioptric or lens telescopes, utilize lenses to gather and focus light, enabling astronomers and enthusiasts to observe distant celestial objects. The basic principle behind a refractor telescope involves the refraction of light as it passes through different glass elements, which bend the light rays and converge them at a single focal point.


  • Excellent Image Quality
  • Low Maintenance
  • Versatility
  • Color Correction


  • Cost
  • Size and Weight
  • Chromatic Aberration (not an issue for apochromatic (APO) refractors)
  • Limited Aperture Size

    In conclusion, refractor telescopes use lenses to gather and focus light, providing excellent image quality and versatility. However, they can be costly, and larger apertures can result in increased weight and chromatic aberration. Despite these drawbacks, refractor telescopes remain a popular choice for both amateur and professional astronomers, especially for observers who prioritize image quality and ease of maintenance.

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    Reflector (Catoptric)Telescopes

    Reflector telescopes, also known as reflecting telescopes, are optical telescopes that use mirrors to gather and focus light, enabling astronomers to observe distant objects in the universe. The basic principle behind the reflector telescope involves the use of a primary mirror to gather light and a secondary mirror to direct the light towards the eyepiece or camera, where the image is magnified and observed.


  • Large Aperture
  • Cost-Effective
  • Minimal Chromatic Aberration
  • Collapsible Designs


  • Maintenance
  • Obstruction in Optical Path
  • Bulkier Design

    Despite these drawbacks, reflector telescopes remain a popular choice among astronomers due to their cost-effectiveness, larger aperture capabilities, and ability to provide excellent views of celestial objects. Advancements in technology have also led to innovative solutions that mitigate some of the cons associated with reflector telescopes.

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    Catadioptric (Compound) Telescopes

    Catadioptric telescopes, also known as compound telescopes, are optical devices that use a combination of lenses and mirrors to gather and focus light, allowing astronomers and enthusiasts to observe distant celestial objects. These telescopes are popular for their compact design and versatility, offering both reflector and refractor features.


  • Compact and Portable
  • Versatility
  • Reduced Chromatic Aberration
  • Longer Focal Length


  • Cost
  • Weight
  • Cooling Time
  • Requires Collimation

    Catadioptric telescopes offer a balanced combination of features from refracting and reflecting telescopes, providing excellent image quality, compactness, and versatility. However, they may come with higher costs, weight considerations, and potential collimation challenges.

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    Aperture Size

    Telescope Aperture Explained: Does Size Really Matter?

    • f/2 - f/5
      • Low Power
      • Wide Field
      • Deep space astrophotography
    • f/6 - f/10
      • Most Versatile
      • Farily Good For Most Uses
    • f/11 - f/15
      • High Power
      • Narrow Field
      • Planetary Observing
      • Lunar Observing
      • Binary Stars

    This describes the "speed" of a telescope's optics, which is determined by dividing the aperture by the focal length. A smaller f/number corresponds to lower magnification, a wider field of view, and a brighter image when using any eyepiece or camera.

    Fast focal ratios, typically between f/4 and f/5, are ideal for low-power wide-field observations and deep space photography. On the other hand, slower focal ratios ranging from f/11 to f/15 are more suitable for high-power lunar, planetary, binary star observations, and high-power photography. Focal ratios in the medium range, around f/6 to f/10, perform well for various purposes.

    Comparatively, an f/5 system can capture images of faint extended deep space objects like nebulae in only one-fourth the time it takes for an f/10 system, albeit resulting in an image that's half the size. However, it's important to note that point sources like stars are influenced by the aperture rather than the focal ratio. Therefore, a larger aperture enables you to observe or photograph fainter stars regardless of the focal ratio.


    There are many things to consider when choosing which telescope to purchase. We understand that it can be daunting, especially as the quality (and price) of the telescope goes up. Rest assured that no matter which telescope you decide to take home, you will be glad with your decision the moment you look through the eyepiece and unravel the beautiful world above us. If things didn't meet your expectations you can leverage our unique 30-day no cost returns and send it back to us for free if your item is qualified for a return.


    Happy Observing!




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