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Choosing the Right Dobsonian Telescope Aperture: A Guide to Common Sizes

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Table of Contents

Introduction #

Dobsonian telescopes are a popular choice among amateur astronomers due to their affordability, ease of use, and large apertures. When it comes to choosing the right Dobsonian aperture, there are several factors to consider. In this post, we’ll discuss common Dobsonian apertures, focusing on 8-12", while also providing information on smaller and larger sizes. We’ll cover the benefits and drawbacks of each size and provide example telescopes for each aperture.

What Does a Larger Aperture Provide? #

A larger aperture allows a telescope to gather more light, resulting in brighter and more detailed images. This makes it easier to observe fainter celestial objects, such as galaxies and nebulae. A larger aperture also improves the telescope’s resolving power, allowing it to distinguish finer details and separate closely spaced objects like double stars.

Additionally, aperture can be crucially important if finding a low Bortle area, or Dark Sky, is particularly difficult. That said, higher aperture is never a replacement for better (darker) skies!

8" Dobsonian Telescopes #

An 8" Dobsonian is an excellent choice for beginners and intermediate observers who want a balance of affordability, portability, and performance. This size is capable of showing detailed views of planets and many deep-sky objects.

Additionally, 8" Dobsonians are often kept long-term by enthusiasts, even after upgrading to larger models or branching into other telescope types (like Refractors). This is due to their optimal performance/portability ratio. Therefore, this can be a great 1st scope if you reasonably see yourself upgrading or adding more scopes to your repertoire in the near future.

Pros #

  • Affordable
  • Good light-gathering capability
  • Suitable for observing planets and deep-sky objects
  • Relatively portable

Cons #

  • May not reveal as much detail as larger apertures
  • Not ideal for astrophotography
Orion SkyQuest XT8 Classic Dobsonian Telescope

10" Dobsonian Telescopes #

A 10" Dobsonian offers a significant step up in performance compared to an 8" model. In fact, a 10" aperture would gather 3x as much light as a 6" scope. The increased light-gathering capability allows for more detailed views of celestial objects and makes it easier to observe fainter deep-sky targets.

Like most middle-grounds, 10" is the sweet spot between cost, portability, and capability for most people.

Pros #

  • Improved light-gathering capability compared to 8" models
  • Better resolution and image brightness
  • Suitable for observing a wider range of deep-sky objects

Cons #

  • More expensive than 8" models
  • Heavier and less portable
Apertura AD10 10" Dobsonian Telescope

12" Dobsonian Telescopes #

A 12" Dobsonian provides impressive light-gathering power and is ideal for observers who want to explore faint deep-sky objects. However, its size and weight can make it more challenging to transport and set up.

Pros #

  • Excellent light-gathering capability
  • High resolution and image brightness
  • Ideal for observing faint deep-sky objects

Cons #

  • Expensive
  • Heavy and less portable
  • May require a stepladder or stool for comfortable viewing
Sky-Watcher 12" Flextube Dobsonian Telescope

Smaller and Larger Apertures #

Smaller Dobsonian apertures, such as 6 inches, are more affordable and portable but may not provide as much detail or brightness in their images. They are still suitable for observing planets and some deep-sky objects, making them a good choice for beginners or those with limited storage and transportation options.

Larger apertures, such as 16 inches or more, offer exceptional light-gathering power and can reveal stunning details in celestial objects. However, they are expensive, heavy, and often require a ladder for comfortable viewing. These telescopes are best suited for experienced observers with dedicated observing sites and the means to transport and store them.

Summary Table #

ApertureProsConsExample Telescope
6"Affordable, portableLimited light-gathering capabilityOrion SkyQuest XT6 Classic Dobsonian
8"Good balance of affordability & performanceMay not reveal as much detail as larger aperturesOrion SkyQuest XT8 Classic Dobsonian
10"Improved light-gathering capabilityMore expensive, heavierApertura AD10 10" Dobsonian
12"Excellent light-gathering capabilityExpensive, heavy, may require ladderSky-Watcher 12" Flextube Dobsonian
16"+Exceptional light-gathering powerExpensive, heavy, ladder neededOrion SkyQuest XX16g GoTo Truss Dobsonian

References #

  1. Selecting the Right Telescope Setup — Sky-Watcher USA
  2. Apertura Telescopes
  3. A Guide to Choosing a Telescope for Beginners - Sky & Telescope
  4. Telescope Specs Explained - Astronomy Source
  5. Best Dobsonian Telescopes - Astronomy Source
  6. Orion Telescopes & Binoculars: Dobsonian Telescopes

Choosing the right Dobsonian aperture size ultimately depends on your observing goals, budget, and portability needs. We hope this guide has provided valuable information to help you make an informed decision. Clear skies and happy observing!