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Why Are Binoculars’ Lenses Orange?

Last Updated: 15.07.24


Observing wildlife and natural landscapes is significantly enhanced when binoculars are employed. From how they work to the type of lenses used, this article will help you find out more about the anatomy of these pieces of optical equipment and what you can do with them. 

Whether you’re a nature-explorer interested in watching birds up close, observe the various rituals and habits of wildlife, or simply admire nature wherever it unfolds its beauty, today’s optical gear can help you considerably enhance your experience and enjoy speechless views without even moving much. 

Binoculars, spotting scopes, monoculars, and other such optical tools were designed to bring you closer to the items of your interest without getting physically too close to them. While sometimes it is easy to observe nature and animals without using such equipment, there are times when keeping them at a distance is compulsory in order to keep you safe. 

If you’re new to this and you want to learn more about these optical tools, this post might be of help as we have covered some of the most important things regarding the anatomy of binoculars, the way they work, and why their lenses are colored. 

Types of lenses and how they work

Everything you will find in binoculars counts when it comes to what the unit can do and the results you get yet the lenses used are some of the most important parts. Their type and quality will directly affect what you see when using binoculars. 

Coming in all shapes and sizes, binocular lenses are designed to focus light rays from a great distance in order for you to see things that are far away from you clearly. Thus, lenses are the key component of binoculars, telescopes, and other such optical items. 

Now, lenses are not the same although they may look so at first glance, especially if you’re new to these pieces of equipment. While a convex lens will bring distant light rays into a focus and thus make them come together, a concave lens will make light rays diverge, the reason why it is also called a diverging lens. 

Convex or converging lenses are used to make things look bigger and thus employed in items like magnifying glasses while concave or diverging lenses are used in equipment such as movie projectors.


Lenses and binoculars

If your outdoor activities require optical tools that would enable you to see clearly something that is far away from you, then you could go for two convex lenses that are placed one in front of the other. You would need two of them because the first one would catch the light rays from the object that is far away from you making a focused image behind the lens. 

This first lens is also known as the objective since it is the nearest lens to the object that is being observed. A single such lens wouldn’t help you much without a second one, though. The second lens used will basically pick up that image and magnify it. That’s how telescopes work. Binoculars are actually two telescopes placed side by side yet there is a catch. 

If you’ve ever used a magnifying glass, you might have seen things upside down and that’s because light rays from an object that is far away from you cross over when they pass through a converging lens. The second lens won’t help you solve this problem. Here is where binoculars are different. 

They feature the so-called prisms to deal with this issue. Prisms are large wedges of glass employed to rotate the image so you can see things as they are and not upside down. Binoculars use two such prisms. 

The first one will rotate the image of your object of interest by 90 degrees, basically flipping it onto its side, and the second one will do the same again. This way you get to see the object as it is in real life. 

Depending on the model you choose, you will either have roof prisms since these wedges of glass are placed in a back-to-back arrangement or Porro prisms when they are arranged at 90 degrees. This is the reason why some binoculars are heavy. Of course, you could always go for field glasses to get rid of this uncomfortable aspect yet the image quality delivered is poorer.

Field glasses are compact binoculars that turn the image with the use of lenses only. Because there are no prisms employed, they are lighter and more comfortable yet the quality of the image is reduced as well. 

Lens coatings

You might wonder why the quality of the image you get differs from one model of binoculars to another. The answer points to the lens coatings used. Light might be lost when transmitted through a lens since it may reflect off its surface. To enhance light transmission and minimize reflective loss, manufacturers use lens coatings that are nothing else but thin chemical coatings.

Since spotting scopes and binoculars feature a greater number of lenses inside, coatings thus become even more important. When the lens is left uncoated, up to 5 percent of the light transmitted through it can be lost. Therefore, multi-coated lenses will significantly reduce light transmission loss.

Moreover, they improve the quality of the image by optimizing the basic color transmission. High-end optics might feature even up to 80 thin coatings for enhanced results. That’s why you might find binoculars described as featuring multi-coated lenses. 

The market offers different types of coated lenses. You will thus see lenses simply described as coated. This usually means that a thin anti-reflective coating has been used on one surface of the lens or on several surfaces of the lenses featured. 

When it comes to fully-coated lenses, the objective lens system and the ocular lens system have at least one thin anti-reflective coating applied to both their sides. Such a coating is also applied to the long side of the prism. 

As the name suggests, multi-coated lenses feature multiple layers of coatings. These coatings are applied to one or more lens surfaces. In the case of fully multi-coated lenses, you get several layers of coatings on all lens surfaces. Such lenses are usually found on high-end models. 

When looking for new binoculars for your outdoor adventures, you will also find units that are phase-coated. This means that roof-prism binoculars feature a phase-correction coating on one side of the prism employed. 

This coating is a thin layer of dielectric material that is committed to delaying light waves and to allowing for the peaks of light waves to come back in phase. This translates into reduced interferences and enhanced sharpness and brightness. 

Coating colors

You may have seen binoculars that have orange, green, or purple lens colors and maybe wondered what that is so. This is how you actually know if the lenses are coated or not. Simply check the objective lens and the reflections of artificial light in it. If you see one of the colors mentioned above, then you know the lenses are coated. 

In case the light you see is clear, then the lenses feature no coatings. Orange coatings are used to cut down glare and thus improve contrast so you get better image quality even in hazy conditions.

However, you might also find ruby-colored coatings which are used to reduce chromatic aberration and remove red light from the image. Although they manage to do that, the image delivered has a blue-green cast and brightness is also reduced. 

Some coatings are used to eliminate blue from the image and thus enhance contrast but the images delivered may get a yellow tint. Depending on the activities you engage in and that require the use of binoculars, you can choose between these coatings. 

Seeing true colors is vital in certain cases. If you’re a bird-watcher interested in evaluating plumage, you might want to go for neutral lens coatings for better results. 

There is another aspect you might want to consider when looking for binoculars as far as the coatings applied are concerned. In case you intend to use the binoculars even when the weather gets less pleasant, you might want to try a waterproof model that comes with water-repellent coatings. 

Such coatings are applied to the outside of the eyepieces and objective lenses. What these coatings do is to prevent water from sheeting and help it form beads instead. This will make it easier for you to clean the lenses as dirt won’t stick too easily. 



Ioana Moldovan

Ioana’s professional experience in the optics field has helped her understand the value of passing her knowledge forward. Her curious personality helps her gather useful information for her readers and her goal is to make technical information fun and accessible to everyone.

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