Celestron C9 25 Vs C11

Looking for a new telescope can be challenging because there are so many good options out there such as Celestron C9 25 Vs C11. Both of these models are very much similar to each other as they are also coming from the same line. They are ideal for those who plan to hunt spots with their telescope but, before you make a decision, let’s see what these two siblings can offer here so then we can choose the best option wiser.

In this article, we are going to give you information about:

  • What to Pay Attention to in a Telescope
  • What are Celestron C9 25 and C11
  • What Celestron C9 25 and C11 Look Like
  • How are the Specification of Celestron C9 25 and C11
  • How are the Performance of Celestron C9 25 and C11
  • How are the Mounting of Celestron C9 25 and C11
  • Celestron C9 25 Vs C11

Telescope Important Factors

Facing two or more options can be confusing because all look attractive and sometimes we are not sure yet about which will fit in our application the most including when looking for a telescope. We all know there are plenty of good options out there which seem to be too similar to each other but are actually different. It is time saving to go for any model made for our goal but it is better to know at least a little bit about the unit before purchasing.


We are sure you have heard this so many times but in a telescope the most important part will be their aperture or the diameter of the light capturing lens/mirror. The reason why it is crucial is because the essence of a telescope is to gather as much light as possible in order to let you see the object it is aiming at. The key element is how wide the area used to gather light and it also means brighter, clearer image; doubling the aperture means quadrupling its light-gathering ability.

Focal Length

This is another necessary part to consider when looking for a telescope and it does affect the image we see through the eyepiece prominently. Simply said, focal length is an effective distance from the lens or mirror to the focal point where your eyepiece or camera is placed. If you are using a refractor or reflector, the focal length is the actual distance from the lens or mirror to focal point. On the other hand, a catadioptric design is a bit different.

In the most popular catadioptric design like an SCT Celestron 60AZ Vs 70AZthe optical path is actually folded as it is bouncing off two mirrors. If you have an SCT, the distance from mirror to the focal plane is almost twice the length of the tube yet, since we have to count the curvature as well, your effective focal length will be about five times longer than the tube.

Focal Ratio

This is related to the focal length as it is simply a ratio between an aperture with the focal length so an 200mm or 8-inch model with an 1000mm focal length will have a f/5 as the ratio. It is not actually affecting the image in terms of observation unless it is extremely low which is not normally seen in commercial models but with all things being equal, larger focal ratio means the telescope has fewer inherent aberrations yet, in practice the difference is often not noticeable.

 Celestron C9 25 Celestron C11
Product Dimensions17.4 x 16.3 x 28.7 inches30.5 x 20 x 19 inches
Shipping Weight28.6 pounds20 pounds
Best offerCheck priceCheck price

What makes some people often consider this factor is because it will affect your photography. In general a longer focal ratio is called as slow while the shorter models are fast and this relates to how fast the image can be captured by your camera. It can be a huge difference that decides how long a picture can be taken so faster models can capture pictures that slow models need hours to in just mere minutes.

About  Celestron C9 25 and C11

The choice is all yours since we may want to focus on different factors based on which seems to fit in your type of application so overall there is no one telescope that can be the best choice for everyone. If you are here however, the catadioptric design may benefit you the most be it on the effective focal length to cost or due to its convenience for traveling. They are also very popular so chances are every brand offers a line or more for their SCT or Maksutov.

Personally we like to stay with popular names as they are a guarantee to quality and when talking about telescopes, it is difficult not to also talk about Celestron. We are sure most people are familiar with this brand already because they are one of the main players in the market. We love their telescopes because not only they do reliably but also for the numerous collections from good cheap models for Christmas presents to those made for enthusiasts that cost quite a lot.

For those looking to find a good and reliable telescope with decent aperture, Celestron C9 25 and C11 are going to be two of the most ideal options to consider. Both of them are optical tube assembly and as you can expect, are also using Schmidt Cassegrain for the design. As close brothers they will be almost identical to each other but being different models also means there must be something that sets them apart from each other which may or may not affect your decision.

Besides being equally SCT, have a decent aperture, and compatible with the same mounting, they are mainly different on the aperture as the name suggests. The latter will require you to pay more but this is also because it offers more in the unit and yes, it has a bigger aperture in comparison to C9 25.

Celestron C9 25 and C11 Design

One of the best things of SCT is their length because we can make them more compact and this is what makes Celestron C9 25 and C11 very attractive for those looking at telescopes that can be stored or carried around with less fuss. The difference is quite noticeable between the two as it is at 22 and 24-inch respectively. But, it seems that the rest of built qualities are the same so these models are made with aluminum for the tube while StarBright XLT is used for the optical coating.

These are optical tube assemblies so you won’t get any mounting or tripod in the box and for the saddle itself they are also compatible with the same mount. Celestron usually put one or two eyepieces with each one of their telescopes depending on the model but for these two we only get one eyepiece to start with which is also different in size. In addition, while they do have a finder scope installed, these are two different sizes as well.

Celestron C9 25 and C11 Specification

Moving further, let’s see what both of these Schmidt-Cassegrain OTAs can offer as they also carry some basic differences and starting with the aperture, as it has been mentioned above the C9 25 is smaller in comparison or at 234.5mm (9.25-inch) while the latter is 279.4mm (11-inch). They also have different focal lengths of 2350mm (93-inch) compared to 2800mm (110-inch). What stays the same is their focal ratio because both Celestron C9 25 and C11 are equally an f/10 model.

For the eyepieces, they are packed with a standard optic of 25mm or 94x magnification and 40mm or 70x magnification eyepiece respectively. They also have the same 1.25-inch Star Diagonal but the finderscope is different as C11 comes with a larger and probably better scope with 9×50 type compared to 6×30 in C9 25 so, we hope to get a more accurate aiming as well.

Celestron C9 25 and C11 Performance

Moving to the performance side, both of these optics are actually very much the same to each other. Under the same conditions they can produce the same image quality and are very bright as well as overkill for a close object like the moon. Comparing the Jupiter image from both telescopes they are very close in terms of clarity depending on how clear your sky is. The prominent difference is probably the diameter of an object, especially closer ones as they appear too close with C11.

If you plan on taking pictures of the moon for example, we can utilize a focal reducer to get a better or more surface of the object. For fainter objects, the C11 may make your image look brighter but the longer focal length is not as ideal as the C9 25 to get a wider field of view. As with the finder scope, they are not the best but still useful and aiming with 9×50 is indeed faster.

Celestron C9 25 and C11 Mounting

The last part we want to mention is their mounting and as you may already know, both Celestron C9 25 and C11 are using the same saddle which is the D style mount or CGE mount that you can get from Celestron as well. If you already have the compatible mount such as CGE Pro which is also computerized, we can skip the shopping process or if needed we can also use adapter to bridge between two different saddles.

Celestron C9 25 Vs C11

Both of these siblings are amazing options, not only because their compact design lets them be travel friendly but also because of the good built quality and optics. They are capable of delivering bright images mostly for further objects as they do have longer focal length and the fairly slow focal ratio made them more ideal for lunar, planetary or binary stars. In comparison you will get the same image quality with the C11 being closer to an object.

- 9.25" Schmidt-Cassegrain, 2350mm focal length (f/11) Aluminum Optical Tube.
- Starbright XLT Multi-Coatings.
- 6x30 finderscope.
- 25mm eyepiece (94x).
- Large 11" aperture and long focal length of 2800 mm
- StarBright XLT optical coatings
- Aluminum optical tube
- 25 mm eyepiece


All in all there is no bad option between the two as you can find them equally amazing in application be it for observation or photography but considering the price gap, personally we are opting toward the C9 25 as it can do amazing while also saving you some to get another accessories may needed.


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