20×80 vs 25×100 Binoculars For Astronomy: What’s Better?

20x80 vs 25x100 binoculars for astronomy

Buying your first binoculars for astronomy may be a difficult decision but you narrowed down your options for two main model sizes: the 20×80 vs 25×100. What is the difference between 20×80 vs 25×100 and which one is better for stargazing?

Which is better for astronomy, 20×80 or 25×100? The 25×100 have better magnification and lens diameter which offers solid low-light performance, whilst, 20×80 have a wider field of view, is more portable and cheaper (about half price). If you plan on buying a telescope, buy the 20×80, if not, 25×100

Quick answer, quick resolve. But before you go, let’s have an in-depth look with all the available options to have a clearer image about what you are going to spend the money.

20×80 vs 25×100 binoculars for night sky observations

There are quite a few manufacturers which they sell both of the options such as Celestron Skymaster, Orion and some other mixed manufacturers who may produce only one model of the two, but in general 20×80 binoculars are easier to be found on the market.

The reason the 20×80 binoculars are easier to be found on the market and on different retails and shops is because of the price (yes, a 20×80 can be even half price of a 25×100), size and for many observers is more than enough to have a 20×80 and need no more.

But with 25×100 comes some more advantages. Now let’s narrow this down to advantages of both model sizes, fore a clear understanding.

The advantages of 25×100 binoculars in astronomy.

  • Larger objective lens diameter for better night sky observations
  • Better magnification than the 20×80 model
  • Great binoculars for the moon, planetary observations and deep-sky objects.
  • You may not need any other binoculars for night sky observations as they are absolutely gorgeous.

The advantages of 20×80 binoculars in astronomy

  • Cheaper than the 25×100 models
  • Larger field of view
  • Smaller in size, more portable
  • Easier to be found on the market and major retailer networks

The Similarities between 25×100 vs 20×80 binoculars.

  • Both versions have the exit pupil of 4mm
  • You will need a tripod for both versions
  • By the same manufacturers, both versions may have the same optics inside.

Both of the versions, 20×80 and 25×100 have their advantages, and still, one to be bought. But which one? Let’s answer a few more questions.

According to many stargazers, 20×80 are way more practical than the 25×100, easier to carry around and to mount, to observe with and have a wider field of view and are the main choice if you relate on further buying a telescope for planetary or deep-sky observations.

Thinking about the weight of a telescope and how you may carry around, to carry also a 25×100 which is nearly double in weight than 20×80, may be an issue for some people, also, if you have to commute by foot to a place where to perform night sky observations, to have a 20×80 it is more practical

But what about 25×100 binoculars? If you want to perceive more details on the night sky and deep-objects observations, moon and planets, a 25×100 is an absolute beast with no doubt that this will be the favourite choice for every passionate about astronomy, if you are not going to buy a telescope and don’t mind the extra weight to carry around.

This indeed, 25×100 are heavy and bulky. It may be impractical to carry a telescope and a 25×100 with you, but, unless you may not need or decide not to carry both a telescope and a 25×100, this would be the perfect power you need for amazing observations to perform.

The extra 5x magnification can be crucial when performing moon and planetary observations and may help you better identify the Jupiter belts or Saturn ring. The ISS (international space station) can be also identified and observed with a 25x magnification.

And the extra 20mm in lens diameter is a crucial step for deep sky observations, as you may need as much light as possible to observe faded stars, clusters, galaxies and different messier objects magnitudes.

25×100 vs 20×80 quality, price, weight and more.


In terms of quality, there are no noticeable differences as observed between the 20 and the 25 version if it’s produced by the same manufacturer. But one thing to keep in mind is that collimation may be a problem overall, in special in night sky observations and with high magnification and aperture binoculars.

As an instance, the 25×100 may be more sensible on observing collimation than 20×80. What is collimation?

Collimation is the alignment of all the optical elements along the binocular optical axis. In results, the image you may observe through binoculars may look doubled, therefore, in astronomy, you may see a star doubled rather than a single star, which has a major impact on the observer’s experience.

There are ways on the internet you can collimate the binoculars by yourself, but in the worst case, I would strongly recommend to return them for another copy.


I did mentioned earlier that the price of a 20×80 is much cheaper than 25×100, as an instance, at the moment I am writing this article, the 20×80 from Celestron Skymaster binoculars costs around $150 and the same Skymaster but 25×100 costs $295. I do have to mention also that there are two versions of Skymaster 20×80, and the second (newer) version costs around $210

In general, if you can afford the 25×100 and you consider as this being your choice, I would say go for it, but other ways, if you consider that you may not afford the 25×100 and you may not really need it or there are more advantages you can benefit from 20×80, then I would say go for this version.

In the end, all products are price-related and every each of us we are trying to create a good balance between quality, price and the need of a specific binoculars version rather than going and buying it blindly.

So, balance it carefully when you consider the price.


I mentioned once or twice above that the 25×100 is very bulky and heavy. It is true. As an instance, the Skymaster 25×100 weight around 4.4 kilograms. This is heavy, without to take into consideration the weight of a tripod also.

The 20×80 version from Skymaster weight about only 2.1 kg (4.6 pounds).

In the end, if you consider a good pair of binoculars for astronomic observations and you are often commuting to a place where you can carry the observations or travelling, I would recommend the 20×80 version in this case for good quality performance and better portability.

But if the weight for you is not a big issue, the 25×100 version can be also taken into consideration.

The ugly truth

The 25×100 is a leap forward from 20×80 or from the 20×50 version (which I do not recommend at all for astronomy), and I want to help you make a decision and not to take one for you, therefore, it is a good practice to balance all the above positive and negative aspect of both versions and consider which one may be the best for you.

Although the objective lens diameter of 100mm is huuuuge on a pair of binoculars, it is the same size or bigger than the majority of novice telescopes, and consider that you have two objectives of 100mm. The kind of observations you can take through those ones are outstanding.

A while back I had a Maksutov Cassegrain telescope 25-75x70mm and often I used it for astronomical observations at 25x where I could get a wider field of view when observing deep-sky objects. A 70mm lens diameter was an amazing pick for me at that time and I could observe so much and that was the telescope I initiated myself in Astronomy before I built my own refractor (half-failed).

This said to reflect the fact that even with a 20x80mm you can do outstanding night sky observations and have a good experience, and if you do not need the 100mm version, you may not have to buy it and you can spend the extra money on a good tripod for your 20x80mm, in special if you may have to travel a lot in order to stargaze.

But now, please do not go and buy the 20x80mm for this sake. If you plan to buy or you have a telescope, you may not need the 100mm version, unless your telescope lens diameter is under 100mm. Then I would recommend going for 25x100mm.

If you do not have or if you are not going to buy any telescopes and want to stargaze only with a pair of binoculars, then a 25x100mm will do wonder and this would be my recommendation.

But in the end it is your final decision. Make sure that you research these before you make your purchashe, and please leave a comment in the section below with your opinion and why you may choose one binoculars over the other. This would be really appreciated.

For now, I have to say goodbye and see you around! If you enjoyed our article 20×80 vs 25×100 binoculars please give us a share!

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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