How do choose binoculars for astronomical observation?
One of the easiest ways to conduct a spacewalk without leaving Earth is to scan the night sky with binoculars from a comfortable recliner on a clear, night. Any optical aid can give you more or less depth of vision than you can see with your naked eye. But for the best experience, make sure you choose binoculars that are designed for astronomy.
All binoculars, regardless of size or quality, can give you something. It’s just that certain types of binoculars are better suited for astronomical observations.
The various styles of binoculars on the market are often overwhelming. For hundreds of years, different styles of binoculars have generally been based on the same basic type and remain popular on the market, so any improvement in manufacturing techniques has been mined out. However, this also reflects the maturity of the manufacturing technology of binoculars.
So when a new pair of binoculars stand out in one respect, you might want to compare the rest of its features to find out what’s missing. This includes usability, portability, and price. In a sense, choosing the right binocular mirror is equivalent to choosing which standards you can lower your requirements. The following simple instructions may help you.
1. Binoculars and telescopes
The telescope is big. Even small telescopes are larger, heavier, and longer than most binoculars. Therefore, the telescope needs to be mounted on a tripod or rocker case for stability. Tilting a long tube toward the sky can make the wobble problem worse. But binoculars can lock your eye sockets tightly, and you can keep your hands close to your face for more stability. This is where binoculars have an advantage over the best telescopes available.
Telescopes do make things look bigger. But their main job is to focus on light. Paradoxically, the more a telescope magnifies an object, the dimmer it appears. This is a problem when looking at deep-space targets such as comets, galaxies, and widely dispersed star clusters. This is a problem for everything, really, except the moon, which can be too bright.
The telescope revealed a small area. Binoculars have a wider field of view, allowing you to scan objects in the sky. Binoculars can give you a better idea of how objects relate to each other. They give you a better chance of seeing patterns in the universe.
Many telescopes will show you an inverted sky. Some even let it “go backward” — as if seen in a mirror. Binoculars give the world the right perspective.
2. Magnification and caliber
Each binocular telescope has dual performance indicators, such as 6×30 or 8×50. The first number indicates magnification. The second number indicates the caliber (in millimeters) of its objective lens.
Beginners tend to think that larger magnification is better. High-magnification binoculars are not only better at protecting against light pollution, but are also suitable for observing binary stars, star clusters, and objects such as Jupiter’s moon. But high magnification means a narrower field of view. Worse, the high magnification will increase the shaking caused by shaking hands.
The larger the caliber, the brighter the star. The last thing you should do is lower your standards. Many objects are hard to see, not because they are small, but because they are so faint that larger telescopes are needed to pick up enough starlight. An 8×50 binocular has about twice the light-gathering power of the 8×35, making the viewing object about 0.7 magnitudes brighter. But the trouble is that the 8×50 telescope is large and heavy, making it extremely unsuitable for prolonged daytime use.
For hikers and bird-lovers, 8×35 binoculars are a good choice, and you can even choose 7×30 or 6×24. Magnification and light collection capabilities can be sacrificed for the portability of binoculars. In addition, if there is a way to reduce the shaking of the telescope during observation, the observation effect of a 10 x 30S telescoped telescope is as good as that of a 7 x 50S telescope.
3. Which binoculars are right for you?
Now we’ve seen why you might want to choose binoculars over telescopes. It’s time to think about what to look for when choosing the best binoculars to meet your night sky needs. There are some basic things to keep in mind when choosing between binoculars:
(1) Check the specifications
Understanding several types of numbers can help you determine which binoculars are best for your specific purpose. We will give you this information in descending order of importance.
(2) Competition between quality and price
Let’s say you decide to buy an 8×50 double cylinder (this option is more suitable for astronomical observation), you might find three seemingly identical models at vastly different prices: $49, $180, and $1,000. Is the price equivalent to the actual value? It’s a conceptual problem, obviously 20 times more expensive is not the same as 20 times better quality. Please don’t go to the extremes of low and high prices, you can choose the middle class.
Some manufacturers offer binoculars at different quality levels, poor, medium, and excellent performance. Careless and casual users may opt for the cheapest model. Amateurs should at least consider “better” when it comes to demanding astronomical observations. Of course, once you decide on the make and style, you may find a bargain at a thrift store.
Buying used binoculars may seem like a great way to save money, but you should pay attention to the quality.
(3) What does “x” mean?
You’ll see seals on each pair of binoculars: 12×70, 25×100, etc. The two numbers are separated by an “X”. You can think of “x” as “by”.
The first number is a measure of power, which means: How much will these binoculars magnify? The second number is the metric diameter of the large round glass lens on the front.
Thus, “25 x 70” refers to an instrument that can make objects appear 25 times larger with an objective lens with a diameter of 70 mm.
(4) Are they waterproof?
We live on a water planet. Water is an ever-changing state as local temperatures fluctuate, and sometimes it condenses on your binoculars. Sometimes it rains. Sometimes you throw them into the sea.
So depending on when, where, and how you plan to use waterproof binoculars, viewing waterproof binoculars can be a problem.
Many modern binoculars are rubber-clad. Good for water and shock resistance.
But cheaper binoculars can come out of the factory with built-in water problems. Can seal off steam-filled air and wait for binoculars to fog, bead, or rust. Look for products that have been “nitrogen purged” before the manufacturer bottles them.
(5) Do they have a tripod adapter?
You discovered the andromeda galaxy (M31) with your 2-pound 10×60 binoculars. Now, you want to see it, or you want to show it to your partner, too. Wouldn’t it be a good idea to park your binoculars in the sky? To do this, you need to make sure the binoculars have screw mounting points for supporting the system.
The problem with camera tripods is that most of them are hopeless beyond about 30 degrees above the horizon. That could miss up to two-thirds of the night sky. Special binoculars are armed and can be mounted on or fitted with sturdy tripods. The best is the articulated parallelogram, which swings smoothly over a wide range of angles. These have counterweights that allow your optics to “float” in front of your eyes. As you might imagine, they cost as much as the binoculars themselves.
4. Test binoculars
Below are some simple tests that will enable you to assess the quality of both cylinders, new or used.
First, compare the workmanship of the binoculars you are testing with that of other brands. Some of them look better made than others. Hold the two tubes and try to bend them gently. If something wobbles, don’t buy a double barrel. Move the tube at the same time, then move the sides separately. A good pair of cylinders should move smoothly and be subject to uniform and constant resistance. In this way, the two lenses can focus at the same time. For “center focus” binaries, the eyepiece frame should not wobble during focusing.
The light source is used to illuminate the interior of the tube and observe the interior through the objective lens. If you find dust or mold on the surface of your eyepiece, don’t buy them. Observe the reflected light from the upper and lower surfaces of the objective lens. If the lens is coated, the reflected light from these two layers will appear blue, purple, or green instead of white. Turn the binoculars until you find the third layer of reflective light reflecting from within.
The lens should also be coated, and the reflected light should never be white. Then, point the telescope at the nearest bulb, still looking at the objective end, and turn the angle of the telescope until you see a series of reflections coming from the inside. The ratio of colored light to white light indicates the extent to which the lens is coated. The coating of the lens is to increases the transmittance and contrast, which are extremely important for astronomical observations.
“Multi-coating” (MC) is the best coating method. Do not be confused by the so-called “full coating”, which may mean that one surface is “full” coated (FC) and the rest is not coated.
Turn the telescope and repeat the test from the eyepiece. Use it to look at the sky or a bright white wall (keep the eyepiece about an inch away from you). Look closely at the small white circle formed near the eyepiece, which is the outgoing pupil of the telescope.
If it has four blurry edges and is roughly square, the transmittance of such a telescope will be greatly reduced. A good telescope must have a rounded edge to its exit pupil. Again, the edges should be surrounded by darkness, not other reflected light inside the tube.
Finally, lift the binoculars to see the object, adjust the distance between the two tubes to adapt to their pupil 5 giant, and then focus on both sides. If it looks gray and hazy, the binoculars have serious contrast problems. If you are wearing a scatter lens, make sure you can see the entire field of view while wearing glasses.
Assuming you’re not wearing a scatterscope, take your glasses off. The “sides” of the binoculars should point in the same direction. If you see two pictures or get tired of your eyes, don’t buy them! Eye strain can quickly become a real headache!
To test this better, first make sure the distance between the two tubes is exactly 5 square between your pupil and then use it to look at distant objects. Hold the binaries slowly a few centimeters away from your eyes, making sure you can always see the image of the object. If the image does not double, it will meet the requirement.
This test can be difficult because people tend to double their eyes. Thus, even the image of a double-barrel that has been accurately checked for coaxial will become double for the first brief time. Non-coaxial is the worst problem with low-priced binoculars; even a small tap can paralyze a functioning binocular. The more expensive ones should be able to withstand a few minor external events.
The size of the field of view is bigger and better. But the image quality at the edge of the field is often very poor. Look at the sharp, right-angled edges of the object and check the distortion of the straight line at the edge of the field of view. The distortion should be extremely slight. You’d better look at the black and white lines of things, such as the edges of tree trunks or the edges of buildings against a bright sky, and check for blue or red. None of the binaries can eliminate this aberration, but some may be mild.
Hopefully, these tips will help you when you’re choosing the right binoculars for you.
No matter how you look at the night sky: binoculars, telescopes, or even the naked eye, the night sky is a truly wonderful place. All you have to do is hope for a clear night and lookup. Take your binoculars and check them out tonight!