Every stargazer and astronomy lover needs a pair of binoculars. It’s the easiest way to reach the stars, planets, and other celestial bodies without ever leaving Earth. Just grab them and go outside to scan the clear, dark night sky – you’ll bring the Universe incredibly closer to home.
Like the stars, however, the number of options available in the market is countless. If you don’t get the right type adequate for this hobby, expect that everything won’t be as fun and exciting.
With that, we’ve rounded all the essential things that you need to know on how to pick the most suitable pair of binoculars for stargazing and other astronomy-related activities. In the end, you’d be ready to buy the binos that will start your own adventures exploring the night sky and relish the limitless viewing opportunities in the cosmos.
Why Utilize Binoculars for Stargazing and Astronomy?
Before anything else, you might probably be wondering why use binoculars telescopes for stargazing and astronomy instead of telescopes that are normally tasked for the job. Truth to be told, even the most superior types of binoculars won’t match the viewing capabilities of the larger telescopes. Yet, there are many things that binoculars can provide, making them a perfect alternative or a complement to their primary viewing equipment.
First, binoculars are considerably cheaper than telescopes. While you can purchase a cheap telescope, anticipate that it will only be a source of frustration, given that equipment in the lower price range won’t provide decent clarity and focus.
Unlike telescopes, binoculars allow you to use both eyes, similar to how we view and how our mind is conditioned to see things. Try to squeeze one of your eyes shut and you’ll see how it can be uncomfortable and straining it can be. Stereoscopic (two-eye) vision offers a more detailed, clearer view as the brain has more information to process.
Moreover, the view provided by binoculars is also upright instead of the inverted images from telescopes. With that, the latter provides better context and a greater field of vision, making it easier to move around and match what you’re seeing in the night sky.
Meanwhile, portability and convenience are the most significant advantages of binoculars over telescopes. If you use a telescope, you need to find a clear spot and spend time setting the equipment up. For binoculars, you can simply carry them in your backpack or pocket, or fling them around your neck with a strap. Then, you can grab them whenever you want to get a quick look at the night sky.
With all those perks combined, a pair of binoculars are more likely to give the utmost gratification to stargazers and amateur astronomers.
What can you see with binoculars?
Observing the heavens with binoculars is a great way to appreciate the beauty of the Universe. A good pair in hand on a clear night sky will allow you to see the Moon, planets, binary stars, open star clusters, globular star clusters, comets, asteroids, the Milky Way, and other galaxies.
For instance, you can observe the phases of Venus, identify the Hyades, Beehive, and Pleiades star clusters, see the four largest moons of Jupiter, and look at the brighter nebulas like the Lagoon Nebula and the Orion Nebula. As such, binoculars are truly an excellent option for viewing the entire visible Universe.
Factors to Consider when Buying Binoculars for Stargazing and Astronomy
While the experience that awaits you and the things you’d be able to see in the cosmos are thrilling, buying the best type of binoculars fit for the task can be a daunting task. Fortunately, you can make things a whole lot easier by taking these several factors into account before finalizing your decision and the purchase:
1. Magnifying Power
One of the first things that you need to look at when buying any type of binoculars is the magnifying. After all, you’d be using the tool for its magnification.
The magnifying power is denoted by the first number ending in “x” in the specifications. For example, in a 10×42 binocular, the magnifying power is 10, which means it will make the object appear ten times closer than the view of the naked eye.
The larger the number, the higher the magnification. However, note that you shouldn’t always aim for higher magnifying power. What you should be getting depends on what you want to observe in the night sky.
For instance, if you wish to look at the moon and different star clusters up close, a pair of binoculars with a magnifying power of 10 will do just fine. You can go lower if you prefer to have a wide field of view and a space-walking experience.
On the other hand, you can go higher to pick up finer, more detailed, structures within the star clusters and galaxies. If you’re truly passionate about astronomy, you can opt for binoculars with 20x magnifying power to see the Orion nebula or the rings of Jupiter.
You can even purchase stronger binoculars to view celestial objects that are farther away. Just note that high-powered binoculars tend to be more shaky or sensitive with even little movements, so a tripod may be necessary to get a stable, clear view.
2. Objective Lens Diameter
The number that comes after “x” in the binocular’s specifications pertains to the diameter of the objective lens. For example, in a 10×42 binocular, the number 42 indicates that the objective lens diameter is 42mm.
It’s a crucial feature as it determines how much light the binoculars are able to collect. The larger the number, the larger the diameter and the clearer, brighter, and sharper the image will be. It’s very essential in stargazing and astronomy, given that you’ll be viewing fainter, distant objects in the night sky. More light means seeing greater detail on your target.
If you’re just beginning in stargazing and astronomy, it’s ideal to get a pair of binoculars with a 35mm diameter. As you spend more time with the hobby, you can get binos with a 50mm diameter with a more powerful light-gathering ability for astronomical use.
As you get serious, you can even try 10×80 binoculars that will allow you to see fainter stars. Don’t do it right away, though. The objective lens diameter is relative to the size and weight of the binoculars. The larger the diameter, the bigger and the bulkier a pair of binos will be, making them harder to carry and keep steady. In this case, a tripod can be handy.
3. Field of View
The next thing that you need to consider is the field of view, which pertains to the width of the image that you can see when looking at the binoculars. It is typically expressed in terms of feet or meters over a specific distance, such as 300 ft. per 1,000 yards, or in terms of angles, such as 4.4°, 6°, and 7.5°.
In general, the wider the field view, the better for stargazing and astronomy, especially when you’re viewing the vast Milky Way and the constellations. Be wary that magnification is relative to the FOV. The higher the magnification, the narrower the FOV. High-powered binoculars show only a smaller part of the sky above, but images are more intricate. That’s perfect if you want to view specific night sky targets instead.
4. Prism Type
Binoculars are compact because they utilize prisms. These are glass components that allow the manipulation of light. Thus, increasing the light between the lenses and the eyepiece, and improving magnification without the need to change the optical tube’s size. There are two types of prism styles: the roof prism and the Porro prism.
The modern roof prism binoculars are smaller, lightweight binoculars. If you see straight tube binoculars, it uses roof prisms, where the path of the light from the lenses to the eyepiece is linear. While they appear streamlined and easier to carry around, their internal machinations and optical design are actually more complicated, making them harder and more costly to manufacture.
On the other hand, the traditional Porro prism binoculars use a system first developed by Italian Ignazio Porro in the 19th century. Instead of being linear, the Porro prism binoculars have a path of light shaped like the letter “Z”, giving the binoculars a zigzag or offset form. With that, these types of binoculars tend to be heavier than their roof prism counterparts. Plus, they’re also quite fragile.
Nevertheless, you’ll see most of the binoculars marketed for astronomy and stargazing are using the cheaper Porro prisms. That is because their mechanism allows less light loss, producing a more visible, brighter image, even under the same magnifying power and objective size.
Yet, it doesn’t mean that all roof prism models are inferior to Porro prism models. You’d be surprised that some of the premier binoculars in the world are roof prism models.
5. Exit Pupil
While it’s relatively a less heard factor, the exit pupil and its size are an important consideration when shopping for binoculars. The exit pupil is the round disk where the images form. It should range between 5mm to 9mm, similar to the diameter of the human pupil when exposed to low-light conditions. The larger the size of the exit pupil, the larger and clearer the images are. If the size is smaller, then expect to see a darker image.
To calculate a binocular’s exit pupil size, divide the objective lens size by the magnifying power. For example, a pair of 10×50 binoculars have an exit pupil of 5mm (objective lens size of 50mm divided by the 10x magnification). A 5mm exit pupil is already a good number. However, if you wish to get a better look at the moon, planets, and other celestial bodies, a pair of binoculars with a 7.1mm exit pupil is your best bet.
Take note that experts say that the binocular’s exit pupil must be larger than or at least as large as your own pupil. For instance, if your pupil can only open at 5 mm and you use a pair of binos with a 7.1mm, nearly 2 mm is wasted.
In general, 7mm is the average dilated pupil diameter for individuals aged 30 years or under. As we age, the pupil’s capability to dilate decreases. So, for those aged 50 and up, the average dilated pupil diameter falls down to 5-6mm. With that, a pair of 7×50 binoculars are good for the former, while 7×42 or 10×50 is better for the latter.
Next on the list is the focus. It is divided into two general methods – the central focusing (CF) and individual (IF) – with each of which having its own perks and drawbacks.
Central focusing (CF) binoculars feature a focus wheel that simultaneously adjusts the focus on the left and right eyes. On the other hand, individual focus (IF) binoculars adjust the focus for each individual eye.
If you’re enjoying the hobby of stargazing and the love for astronomy with your family and friends, your best choice is to get a CF binocular. They are much easier to adjust and enable quick focusing, allowing you to share your binoculars with everyone else.
However, if you wish to attain a sharper viewing experience, go for an IF binocular as you can set it based on your eyesight or view two different distances at once. Just expect they can be difficult to learn and may take time to adjust, which is why they are reserved for more experienced hobbyists.
7. Eye Relief
Another essential factor is binocular eye relief. Eye relief is the distance between your eyes and the surface of the final lenses of the binocular piece at which you can still see the entire FOV. It can range from a few millimeters to a few centimeters.
For the best viewing experience, it is recommended to have an eye relief of about 10-12 millimeters. If your eyes are too further away, you won’t see the entire image. Too close and the image will be less clear. If you’re an eyeglass wearer, give some leeway and choose a pair of binoculars with a minimum of about 16 mm eye relief or more, depending on the thickness of your glasses.
Eye relief is also vital for comfort, especially when observing the night sky for extended periods. It’s always better to aim for longer eye relief. If it’s too short, you’ll easily strain your eyes when looking through the binoculars. While most binoculars available in the market today have sufficient eye relief, it doesn’t hurt to devote extra effort to check before buying.
Binocular lenses have anti-reflective (AR) coatings applied to them to reduce glare, as well as to improve contrast and boost image sharpness. Without AR coatings, light transmission in the equipment can fall under a dismal 70%, but with AR coatings, the figure can jump up to 95%. You can see different types of AR coatings with manufacturers generally categorizing them as coated, multi-coated, fully-coated, and fully multi-coated.
Coated means that there’s only a single layer of coating on at least one lens in the equipment. Multi-coated suggests that there are multiple layers of coating applied but not all the lenses. Fully coated means that there is at least a single layer of coating on all lens surfaces, while fully multi-coated implies that there all lens surfaces have multiple layers of coating, which is usually found on high-end optical equipment.
According to experienced hobbyists, a good way to check if the binoculars have AR coating is by looking at the light reflected by the lenses. If the surface is white, it means that there is no AR coating. If the image is ruby-red, it means that a highly-reflective coating is applied, which restricts brightness. Avoid them and instead, opt for ones that have dark lenses with some reflected color as that is what indicates good AR coating.
9. Waterproofing and Fogproofing
You should also ensure that the pair of binoculars you’re getting has waterproofing or fogproofing capabilities to keep all the lenses and prisms away from moisture. Though you won’t be stargazing or viewing celestial objects during a rainstorm, you’ll still do the activity outdoors. It is always better to have a piece of equipment that has enough protection from dew, condensation, or unexpected rain showers, which are all inevitable parts of night sky viewing.
Some models have no rating at all, which means they are less durable as the internal components are vulnerable to moisture. Others are rated as waterproof which suggests that there is some degree of waterproofing, usually by employing a gasket or “O-ring” that prevents water and other debris from reaching the objective. Meanwhile, waterproof-rated models can stay underwater for varying lengths of time and depth. On the other hand, fogproof binoculars utilize fogproofing elements, such as nitrogen or argon, that help keep the insides of the binos free from moisture and fogging. In nature, fogproof binoculars are already waterproof.
10. Price and Budget
Of course, the price of the binoculars will never be out of the picture. Given that in the realm of optics, be it monoculars, night vision goggles, or telescopes, you will always find products with a wide range of costs. The question is, from which price range should you buy?
Expect that there’s a huge difference in the quality and performance between a pair of binoculars costing $30 and another one costing $300. However, you’d be surprised how the difference between a $200 and $2,000 model will not be quickly noticeable for most viewers.
If you’re just beginning with the hobby, it’s best to opt for mid-priced models, which can already provide you with much satisfaction. Just avoid the cheaper one as the initial experience may not be as fun, prompting you not to look back at the night sky again.
Remember that setting a budget can greatly help, too. Once you know how much you can afford or how much you’re willing to spend, you can narrow down your choices and make the selection process far easier.
What types of binoculars are best for stargazing and astronomy?
Now, what type of binoculars should you buy for stargazing and astronomy? The truth is, there is no specific type as the decision boils down to your preference, needs, budget, and other aspects. You’ll be playing a game of balance, weighing all the factors above to ultimately get the perfect binocular for you. Never rush and think of each consideration carefully and you’re soon set to start your journey of being friends with the stars and other heavenly bodies.
The intergalactic space is endless, and the viewing opportunities are also infinite. Just make use of all the information above to get a suitable binoculars. Then, step outside, sweep past through stars, nebulas, galaxies, and planets, and relish all the other fascinating sights that the Universe has to offer.