Honest Full Review: Celestron Skymaster 25×100 Binoculars

Celestron Skymaster 25x200 binoculars review

The Celestron Skymaster 25×100 is considered to be one of the largest regular binoculars used in astronomy and stargazing. I own these binoculars and after using them for a while, I’ve decided to write a full and honest review (not paid).

How are the Celestron Skymaster 25×100 binoculars? Heavy, bulky but marvellous in astronomy. With a magnification of 25x, you can see moon and planets relatively good but with the objective lens diameter of 100mm, you can see deep-sky objects brighter than most of the telescopes on the market.

Despite the advantages of having a very large aperture, these binoculars may come with some disadvantages. I recommend you to further read our review to find out more about the binoculars.

If you are interested in buying Celestron Skymaster 25×100 binoculars you can find them by clicking here (Amazon link).

Celestron Skymaster 25×100 binoculars review

Before to start reviewing the binoculars, I want to share with you the advantages and disadvantages of these binoculars as I know and observed after many usages.

Advantages of the Celestron Skymaster 25×100 binoculars

  • An extremely large aperture (objective lens diameter), one of the largest found in binoculars
  • High magnification of 25x
  • Relatively cheap price for what it can offer.
  • Multi-coated optics with BaK4 prisms
  • Amazing for long-distance terrestrial viewing and astronomy
  • Good texture with great gripping (anti-slide)
  • Good image quality and resolution provided

Disadvantages of the Celestron Skymaster 25×100 binoculars

  • Independent focus system
  • Heavy and bulky
  • May not be the top quality optics
  • Exit pupil of only 4mm
  • Long close-focus distance of 147ft or 45 meters

Understanding the 25x magnification

A magnification of 25x is considered to be high in binoculars. Most of the binoculars are having a magnification of 8x to 10x where you can do any observations handheld. But not with these ones.

With this magnification, to be able to carry any types of observations, you need a strong tripod which is able to hold the binoculars without to put pressure on the tripod neck. Although a tripod or a mount would be ideal for this magnification, beware that at 25x, even the slightest movement will shake the image.

But what you can see through a 25x magnification? Well… A lot, to be honest.

25x magnification in astronomy

Photo taken through the Celestron Skymaster 25x100 with iPhone X
Photo taken through the Celestron Skymaster 25×100 with iPhone X – The moon sized approximately what you see through binoculars.

In astronomy, I was able to observe the moon and barely hug it. Observing the moon with both of your eyes at 25x is celestial and this cannot be explained by any words how beautiful it is!.

You can see Jupiter with the 4 main moons and able to spot details, Venus and even the Saturn with its rings when is in the closest position to Earth.

Magnification is not the main focus for deep-sky observations but as the binoculars have an aperture of 100mm, you are able to spot some finer details on the night sky, locate nebulae and galaxies and much more, where, this won’t be possible not even for some cheap to medium-priced telescopes.

25x for everything else

The first photo is an antenna I was able to see it from approximately 5 miles and the second one (I think) is a power station far away on the sea, barely visible with some good naked eye. Both of the photos were taken through the binoculars (foggy weather conditions)

With this magnification, there’s enough you can view during the day as long as you are able to carry the binoculars with you. For birdwatchers, if you pick a spot with the view over an area where birds are often present, this can overcome the need of normal binoculars as with this magnification you can carry on observations the same way as with a spotting scope but with both of your eyes.

You need a tripod even for any terrestrial observations. You can observe any distant scenes or objects, ships on the sea, sports from afar, plane spotting etc. If you like plane spotting, the Celestron Skymaster 25×100 (Amazon link) is amazing, and here I am talking from my own experience of using them.

Understanding the objective lens diameter of 100mm

Observing through celestron skymaster 25x100 binoculars

As mentioned above, the objective lens diameter (diameter of the main lens) of 100mm is one of the largest found in normal binoculars. You may be able to find some astrobinoculars with larger aperture but very rare and very expensive. As a common pair of large binoculars, these along with the 25×100 from Orion are the largest.

You don’t need such a big aperture for daylight observations but you definitely need for stargazing. The amount of light it can capture is more than most of the regular telescopes found on the market (up to 100mm objective lens).

Moreover, keep in mind that you have the similarity of two telescopes attached together (2x100mm) and although light doesn’t stack, for the simple reason that you can stargaze with both of your eyes, you are able to observe better faint objects on the night sky such as nebulas, galaxies, clusters and much more

In terms of planetary observations, the aperture does not matter as much it matters the magnification. But aperture plays an important role, as well as many planets on the night sky, are faint. You are able to see Jupiter with 4 moons and even some details when is the closest, same for Saturn with the rings, Venus and the Mars, as I mentioned above.

But there should be some disadvantages with the aperture, isn’t it? Yes, it is. Although of the large aperture and the ability to gather plenty of light, using the binoculars during the day in sunny or very bright conditions I would try to be a bit careful (e.g. sunny day during a snowy winter) due to the excessive amount of light it can gather.

There’s no danger behind it, as long as you don’t point the binoculars directly towards the sun or the sun’s reflection, but you need to adjust your eyes to very bright environments before using the binoculars during a bright sunny day.

Binoculars weight & size

The Celestron Skymaster 25×100 weights around 4kg (8.8 pounds / 141 ounce) without the carrying case provided. 4kg in binoculars terms means very heavy to carry around and impossible to carry handheld observations.

You need a strong tripod to set up the binoculars on it. Beware that the regular tripods may not be able to hold that much weight, and even if they do, it may be on the weight limits.

Moreover, the binoculars have a metal axis where the release plate of the tripod can be attached. That axis is not adjustable but the mounting system is, therefore, you can bring the binoculars forward and backwards when on the tripod in order to balance it right and release side pressure from the tripod neck

celestron skymaster 25x100 binoculars vs nikon prostaff 7s 10x42

The binoculars size is massive as well. I cannot give you an exact number as I did not measure it but here is a photo of me holding both in comparison the Celestron Skymaster 25×100 and the Nikon Prostaff 7S 10×42 (guess which is bigger)

Due to the size & weight of the binoculars, you probably cannot use it as a normal/regular pair of binoculars for exploring, hikin&camping, nature observations etc. But you can use them in pretty much any type of observations where you need to have a stable spot and not move around too much (such as stargazing).

The exit pupils, body armour and other details

The exit pupil is the diameter of the light beam going out the ocular lens directly in your eyes pupils. The human eye’s pupils are open about 2-3mm in diameter during daytime and up to 7mm during the night in order to see better in lower lights environments.

In the case of the binoculars pupils, this is calculated by dividing the objective lens diameter to the magnification, in this case, 100/25=4mm. An exit pupil of 4mm it’s great for daylight observations but only on average for night observations. Although of the very large aperture on the binoculars, the exit pupils may suffer a bit.

It is not crucial to consider as compared to gathering the night sky light through those massive 100mm objectives, but still, the exit pupils can have a negative impact on some deep-sky observations where the light is very faint and your eye may not be able to accommodate the amount of light coming through a smaller light beam compared to a larger.

To understand it better, imagine high traffic on a motorway (highway) with 4 lanes. Now cut one lane and imagine the same amount of traffic. A 4mm exit pupil during the night is like a motorway (highway) with 3 lanes on rush hour.

But enough with expressions. In reality, the binoculars are absolutely amazing to observe deep-sky objects in astronomy and rarely you would be able to find better in terms of exit pupils without to sacrifice the magnification or the diameter of the objective lens, which is worse to consider.

diopter and focus adjustment of the celestron skymaster 25x100 binoculars

I personally consider the independent focus system to be a disadvantage as with a focus knob is much easier to focus. When you use binoculars with an independent focus system as the Celestron Skymaster 25×100, you will have a hard time to fine-focus on any distant or closer objects. This won’t be a problem at all if you use the binoculars for astronomy only, as only once you need to focus due to the stars and planets being on an ‘infinite distance’.

25×100 vs 20×80 – Which one?

Now let’s reflect on the main usage of the binoculars: stargazing. In stargazing as mentioned several times already, the binoculars are larger than most regular telescopes and with this aperture, you can see more than you can imagine actually.

But the Celestron Skymaster 25×100 are massive, bulky and heavy. For some people may be hard to carry them for any observations, therefore, an alternative such as 20×80 may sound ideal due to the weight and size difference.

A 20×80 is the “younger daddy” in astronomy and it’s amazing as an alternative for two reasons: you need something lighter and portable or you already own a telescope and it’s pointless to have another giant tool in your arsenal.

Anyway, I wrote a full article about the differences between 20×80 and 25×100 covering everything is about to know, if you are interested.


Although it may not be many stargazing’s choices due to the weight and size, the Celestron Skymaster 25×100 (Amazon link) is a unique pair of binoculars to be used in astronomy and I am happy with my purchase. I recommend it to buy from a trusted seller, official website or if you want, you can check our amazon affiliate link for the binoculars here (Amazon link).

For now, I say thank you for checking out our review and I hope to see you around. Take care!

Gabriel Mihalcea

Passionate about binoculars, photography and blogging with years experience behind, I love to split my time and observe the beauty of this world with different eyes.

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