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Celestron Inspire 100az Review [100mm Short Refractor Telescope]

If you are considering the Celestron Inspire 100az then this review and guide will help you decide whether or not it is going to be best for you.

Here, we will take a look at the specification, what you can expect to observe and some of the main pros and cons behind this refracting telescope from the prestigious Celestron brand.

Bottom Line 

The Inspire 100az is a short Refractor telescope that combines premium Celestron technology with ease of use, portability and great optics. And it does this at an affordable and respectable price point of under $200/£200. With the largest aperture from the Inspire product range (100mm/3.94″), and with a short tube that gives you a wider field of view – this is an excellent telescope ideal for observing planets, the moon, star clusters and brighter deep sky objects like the Orion Nebula and Andromeda Galaxy. Moreover, the Erect Image Star Diagonal (one of the many accessories included) enables you to use the optical tube during the day as a Spotting Scope for terrestrial observations. When you consider its applications, uses and accessories, you’re not going to find many better entry-level telescopes than this.


✔️ Ideal for both terrestrial and celestial viewing. The optical tube can be used as a Spotting Scope for additional day-time use.

✔️ Perfect for beginners and intermediates alike,

✔️ Easy and quick to assemble and dissemble without the need for any tools,

✔️ Lightweight frame makes it easy to carry and take with you on the go,

✔️ Customizable Height through simple Tripod Leg changes.

✔️ Fully coated glass optics for crisp, clear views,

✔️ Alt-Az control enables accurate pointing with relative ease.

✔️ Comes with two eyepieces (20mm and 10mm), a 90° erect image diagonal, an integrated smartphone adapter, a finderscope, a red LED flashlight and Starry Night Software.

✔️ Great specification for a fantastic and reasonable price.

❌ Mount does not have slow motion controls meaning objects can drift out of the scope quickly, and you may need to realign more often to keep objects centred.

❌ Diagonal primarily designed for terrestrial use; you will likely need to upgrade to one more aligned for astronomical observations.

View Customer Reviews and Price on Amazon


Celestron Inspire 100az Review

(Click picture to see more images on Amazon)


Optical Design: Refractor

Aperture: 100mm (3.93″)

Focal Length: 660mm

Focal Ratio: f/6.5

Focal Length of Eyepiece 1: 20mm (1.25″)

Magnification of Eyepiece 1: 33x

Focal Length of Eyepiece 2: 10mm (1.25″)

Magnification of Eyepiece 2: 66x

Highest Useful Magnification: 241x

Lowest Useful Magnification: 15x

Light Gathering Power: 212x the unaided eye

Mount Type: Alt-Azimuth

Weight: 20 Pounds

What Is a Refracting Telescope?

You may be wondering what actually is a Refractor? In short, it is all to do with how the telescope works. Basically, its a type of telescope that uses various components and mechanisms to refract light, compared to reflecting it in (like Reflecting Telescopes do)

A Refracting telescope uses a central Lens that forms the image for you to see (the lens is the objective in a refactor compared to a mirror in a reflector).

Refractors have been in use for centuries, the original design came from Galileo Galilei in the 1600s.

Since then, this popular optical design has evolved whereby there are a number of different refracting telescope types available (Galilean, Keplerian, Achromatic and Apochromatic). They all commonly serve the same purpose; providing a lot of power, at a cheaper price and are much smaller compared to other telescope variants on the market (e.g. Dobsonian).

Features of Great Refractor Telescopes

If you are considering the Celestron Inspire 100az, then its good to know the features that make a great Refractor. Here are the main three:


Aperture is without doubt the most fundamental of the specification to consider. Not just for a Refractor but for any telescope for that matter. Aperture is defined in mm; which simply refers to the  the diameter of the light collecting region of the telescope. The larger this diameter the better as it means it can collect more light and present brighter and sharper images (which in turn allows for more magnification)

In the case of the Inspire 100az, as a Refractor it utilizes lenses. The lens size can be seen in the name for the telescope “100” referring to 100mm Aperture (or 3.94″).

Focal Length

The next element of the specification to be most concerned with is the Focal Length. This ultimately dictates how big the telescope is, the amount of chromatic aberration that you will have and the field of view the scope provides. The focal length is essentially the distance between the lens and the point where the light rays converge.


The relative size and weight of all the components affect its overall portability. The mount will of course add to this. If a telescope has a shorter Focal Length it is typically more portable, but will require better quality eyepieces to ensure great views.

Pros and Cons of a Refractor:

Refractors provide a simple design which makes them a lot easier to use. They are therefore ideal for beginners but because of this you’ll likely find they are slightly more expensive than a Reflector that has the same optical spec. Here is a short pros and cons overview of a refractor in general:


✔️ Simple design without the need for ongoing maintenance,

✔️ Do not require Collimation or Optical Alignment,

✔️ Great contrast in comparison to Reflectors


❌ Tend to be more expensive than Reflector equivalents,

Celestron Inspire 100az Telescope Performance

The Celestron Inspire 100az combines premium components, quality material and great fully multi-coated optics for a reasonable price. It comes with 100mm Aperture (3.94″), a 660mm Focal Length and a f/6.5 Focal Ratio. This is great specification for a beginner or even an intermediate who is looking for a portable and easy to use telescope. When focused, the 100az will deliver high quality images of the Moon, the Planets of the Solar system and some DSO’s (Deep sky Objects) including the Andromeda Galaxy.

Terrestrially, the telescope doubles up to be used as a Spotting Scope which will enable you to use it to enjoy when Bird-Watching, Hiking, or simple land-observations. Just use the provided Star Diagonal and you can easily erect your images.

One of the standout features of this telescope is its ease of use; you can assemble it in a matter of minutes and do not require any difficult tools to do so. In addition, the tripod legs are fully adjustable so you can alter the high of the telescope or even place it on a raised surface. This makes it great for impromptu observation sessions which come by more than you expect!

Beyond this, the Alt-Azimuth telescope is easy to use and to navigate the sky with. All you need to do is move the clutch in an up/down, left/right motion to track your object in the eyepiece.

Here are some other features that users report to be thoroughly impressed with:

Variable and High Magnification

The Inspire 100az comes with two eyepieces; a 10mm and a 20mm. This is excellent and provides you with a variable magnification range depending on your preferences. At the lower end you can expect a 33x magnification and at the higher end it scales to 241x.

StaryNight Software

Purchasing this telescope on Amazon allows you access to Celestron’s Starry Night Software. When you purchase, you’ll receive a download code that enables you to install the software on your PC.

This will help you/ your children learn about the night sky, celestial objects, and how to plan your next observing session.

Smartphone Adapter

The Smartphone Adapter is another highly impressive feature of the 100az. It enables you to connect your smartphone to your telescope (as long as it is wielding a an eyepiece with an outside diameter of 45mm or smaller – like those included).

The extra magnification of your eyepiece will help you to take great photos of whatever it is you are observing, whether that is the the Moon and the Planets or anything on the ground if you are using it for terrestrial purposes (e.g. Wildlife). To fit the adapter, all you need to do is fit it on top of one of the eyepieces (instructions on how to do this are included in the box) and attaching the bungee cords. Your smartphone will then be held firmly in position.

For the most part you can add your smartphone with its case on, but if you have an extra large case you may need to take it off for it to fit the adapter.

Additional Accessories

Celestron provide a comprehensive set of accessories to use with this scope. The following come included in the box:

  • Focuser/ Manual, with a marked micrometer for specific focus-points
  • Inspire Alt-Azimuth Mount with manual control
  • Inspire Tripod with adjustable 1.25 Inch Steel legs, attached fold-up accessory tray, and removable red LED flashlight.
  • 1.25 Inch Diagonal/ Erect Image/ 90 degree
  • 1.25 Inch Eyepiece #1/ 10 mm Kellner, 66x mag.
  • 1.25 Inch Eyepiece #2/ 20 mm Kellner
  • Finderscope/ StarPointer Pro, attached,
  • SkyPortal – downloadable app
  • 2 Year Warranty

That’s a lot of added extras. I particularly like the Finderscope and StarPointer Pro which make observing so much easier and successful. You’ll be able to precisely locate and fix on your target – something that is difficult to do without this component.


This is one of the best entry-level telescopes on the market. If I was new to astronomy, this would be one of those telescopes that I would most likely get.  With its relative power, ease of use, portability, sleek design and the range of accessories make this a brilliant first telescope.

Pricing and Where to Buy

The Celestron Inpsire 100az telescope is available on Amazon. Click here to check the current price of the product on its Amazon listing.

3 thoughts on “Celestron Inspire 100az Review [100mm Short Refractor Telescope]”

  1. Thinking of buying it for daughters xmas, she is wanting a telescope so she can view the craters and mountains on the moon as well as viewing other planets clearly. will this telescope allow her to do that?

    • Hello David. I think the Inspire 100az would be an excellent first telescope for your daughter. It will allow her to see the moon craters and other planets clearly (including Jupiter’s Moons).
      If you head over to the telescopes page on Amazon you can see quite a few images of what you can expect with it in the customer reviews. Youll see some of the moon craters and what they will look like there. Best of luck!

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