Have you recently been trying to get the hang of your new pair of binoculars? Maybe you’ve had some for a while and still aren’t sure exactly how they work. Either way, you might be wondering how exactly do these wonderful pieces of technology work? If that’s the case, you’re in the right place. In this article, we’re going to tell you.
Whether you’re a bird watcher, plane spotter, wildlife enthusiast or enjoy using your binoculars for something else—there’s actually quite a lot of engineering that goes into binoculars. They might seem small and reasonably simple, but it’s taken hundreds of years of expertise and optical knowledge to get to this point. Binoculars aren’t cheap for a reason, they’re an incredibly complex piece of kit. But thankfully, manufacturing processes have meant that they’re a lot more affordable than they used to be. But what actually makes them work? Let’s have a look…
How do binoculars work?
Binoculars use optical glass to use a process called refraction to bend light. This refraction is key to telescopes and binoculars.
Binoculars use the same process as a telescope by magnifying light and making an object appear bigger in the eyepieces than it really is. The main difference with a pair of binoculars compared to a telescope is that they’re a pair – so there’s a place for each eye and the image is magnified into one bigger image for you to look at, like when using your eyes to see something normally.
Binoculars are designed to be portable and handheld, so are much lighter and easier to carry than a telescope. That makes them ideal for bird watchers and other hobbyists who need to be able to quickly look at something in the distance. Because they’re smaller and lighter, they therefore can’t see as far away as a telescope. Ranges can vary, but you won’t really be able to study the stars with a pair of binoculars. That being said, you can still see things at quite a distance with a good pair of binoculars, and they’re great for viewing wildlife and other objects like airplanes.
Binoculars used to be housed in copper casing but this was too expensive to manufacture and also too heavy for regular day-to-day users. Nowadays, they are housed in a mix of aluminum and a strengthened rubber material. Most binoculars are also waterproof.
Binoculars work by using two sets of optical glass. One is the objective, and the other which sites as the eyepiece is used to magnify the original image. You can make a crude version of this to experiment with standard magnifying glasses, and wrapping them in a cardboard tube.
Binoculars are basically two telescopes next to each other. However, when something is viewed from a long distance like this, the image often crossover. This is the reason why distant things sometimes look upside down if viewed through a magnifying glass. That means your binoculars therefore need a bit of extra technology to help put the image back together again the right way up. A set of prisms which are like large wedges of glass sit inside the binocular housing and reflect the image between themselves so it is presented back to you the right way up. These prisms are called Porro prisms. Each prism rotates the image by 90 degrees so that it is flipped the required 180. There are two of these prisms on each side, so four in a set of binoculars.
These prisms are why a good pair of binoculars is quite heavy, and also thick in the middle. Smaller and lighter binoculars don’t flip the image with the same high-quality prisms, so don’t present the same quality image, but are easier to carry. You’ll have to decide whether you value image quality or weight and portability more when you decide which binoculars to buy.
When purchasing binoculars, try not to buy ones that are too expensive to use regularly. It’s all very well having a great set of binoculars, but they’re supposed to be used rather than just sit in a cupboard. Make sure you get them out plenty and get used to having them with you. Get used to the straps. Some people like to have the straps over their head or shoulder. You don’t want to drop your binoculars when you’re in a rush to use them, so the straps are a good idea.
Make sure you clean your binoculars regularly. Carry a little cloth and some cleaning solution with you if you want to. Clouded or dirty binoculars could obstruct what you’re trying to see.
Lighter, more portable binoculars are better for general use and to have with you just in case. But if you’re going to be taking a hobby seriously, you should consider a sturdier pair of heavy-duty binoculars. These are designed to be used from a static location, and are better for bird watching and astronomy. You can still go some astronomy with binoculars, but you might also want to consider a telescope for that.
Binoculars that offer more magnification aren’t always better, especially if you can’t keep the image steady or the eyepieces aren’t big enough to see through very easily. You’ll need to make sure you’ve got waterproof binoculars if you’re going to use them when it’s raining.
While you can find plenty of good offers online, it’s always a good idea to try them in a shop beforehand. You need to get a feel for them and make sure they fit you and you can see through them easily. Make a note of the model you like and try and order it online if you can get it cheaper.
Hopefully, you now know enough about binoculars and how they work so you can start having a look at things in more detail! Enjoy your binoculars for bird watching, wildlife spotting and other fun activities.