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Concave vs. Convex Lens: What’s the Difference?

Phoebe Jade

Written By:

Phoebe Jade

Updated: 19 May 2024 •  
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Ever heard of convex or concave lenses and wondered what their difference is? These lenses help adjust how we see things, similar to the concept behind telescopes or cameras.
 
In this article, we’ll dive into the fascinating world of lenses and explore how they shape our understanding of optics.
 

What’s the difference between concave and convex lenses?

illustration of concave vs convex lens

Lenses are often round, with one or both sides curved like a bubble or a cave. Source: Britannica

 
Lenses are often circular, with one or both sides curved like a bubble or a cave.
 
Convex (converging) lenses are thick in the middle and get thinner toward the edges. They bend light beams inwards and meet at the focal point, making them the go-to for magnifying and creating sharp images.
 
Meanwhile, the concave (diverging) lens is flat at the center and thicker at the edges. They spread out beams, which are great for spreading light and creating smaller, less focused images.
 
A single lens comes with two opposite surfaces, which can either be both curved, or one can be curved while the other is flat. Lenses can be classified based on their surfaces:
 

  • BiconvexBoth surfaces bulging outward.
  •  

  • Plano-convexOne surface flat and another curved outward.
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  • Concavo-convexOne caving inward and another bulging outward.
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  • BiconcaveBoth surfaces caving inward.
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  • Plano-concaveOne surface flat and another caving inward.
  •  

  • Convexo-concaveOne bulging outward and another caving inward.

 
These lenses can bend light rays at different angles because of their curvature. This means that an entire beam of light can be focused on a single point or appear to spread out in every direction.
 
Eyeglasses have single lenses, also used in contacts, pocket magnifiers, signal lights, projection condensers, and even on simple box cameras.

 
Compound lenses are composed of various lenses combined in a tube (to correct aberrations that happen when light rays fail to meet at one focus due to defects or limitations in a lens). They’re used in complex instruments like cameras, microscopes, and telescopes.

 

How do lenses affect our eyesight?

Lenses have come a long way since their early beginnings. In ancient times, people would use simple glass that could magnify things to help them in their tasks.
 
It wasn’t until the 13th century that prescription lenses were invented, allowing those with vision impairments to see clearly. Fast forward to the 17th century, and lenses were used in simple microscopes and telescopes, unlocking the wonders of the microscopic and astronomical worlds.
 
As technology advanced, so did lenses, leading to the development of camera lenses and modern eyeglasses.
 
These days, lenses are pieces of transparent glass (or plastic) that can bend and direct light beams. When light from an object passes through a lens, it gets focused so that we can see an image of that object.
 
a piece of eyeglass lens

A lens is a piece of transparent glass (or plastic) that can bend and direct light beams.

 
Whether a simple lens made of a single piece of material or a compound lens with multiple pieces arranged in a specific way, the result is the same: a focused image. The lens differs from a prism, which only bends light without focusing.
 

Which do I need, concave or convex?

illustration of how corrective lenses correct refrative errors

Concave lenses are for nearsightedness, while convex lenses are for farsightedness. Lenses with concave and convex surfaces can correct astigmatism. Source: ResearchGate

 
A consultation with your eye doctor can help determine which lens type best suits your needs. They’ll be able to perform the necessary eye exams and give you a precise prescription for your lenses. Not only that, but they can also answer any questions you may have about the pros and cons of each type of lens.
 
Generally, concave lenses are used to correct nearsightedness (myopia), while convex lenses are used to correct farsightedness (hyperopia). However, you might not have either eye condition. You may have other eye disorders like astigmatism. This condition can be corrected by lenses with a combination of concave and convex surfaces.
 
Only a comprehensive eye exam done by an ophthalmologist can tell you the condition of your eyes, whether you need prescription eyewear, and what type of lenses you need to use.
 

Other lens considerations to keep in mind

Aside from whether a lens’ shape is convex or concave, here are some other considerations that affect lens choice when picking out eyewear.
 

Lens material affect weights and durability

 
When it comes to picking out eyeglass lenses, there are a variety of materials to choose from. The most common types are plastic and glass lenses, but there are also polycarbonate, Trivex, and high-index lenses.
 
Plastic lenses tend to be the most affordable and lightweight option, making them popular for everyday wear. Glass lenses are durable and scratch-resistant, but they can also be heavy and uncomfortable.
 
Polycarbonate and Trivex (lighter, more transparent, and thicker than polycarbonate) lenses are impact-resistant—ideal for safety glasses or children who tend to be clumsy.
 
Lastly, high-index lenses are perfect for people with strong prescriptions as they are thin and lightweight, making them comfortable for long-term wear.
 
No matter which material you choose, consult your eye doctor to ensure the best fit and vision for you.
 

Lens coatings improve or change lens functionality

 
You can get many different coatings on eyeglasses lenses. There’s blue-light blocking, which can help you protect your sleep patterns and reduce eye strain from staring at a computer screen all day. There’s scratch resistance, which is great for those clumsy moments when your glasses fall off your face (we’ve all been there).
 
And there’s even UV protection to protect your eyes from the sun’s harmful rays.
 
Here at Mouqy, we make sure all glasses lenses come with hydrophobic, anti-glare and scratch resistance coatings by default.
 

You can experiment with various frame styles regardless of lens type

 
Choosing the right frames for your eyeglasses is about hitting that note between functionality and style. With so many different frame styles available on the market, deciding which one is perfect for you can be overwhelming.
 
From square frames to aviators, round frames to cat-eye, and even rimless options, there’s a design out there for everyone. Picking out the ‘perfect’ one for you requires considering your unique face shape, skin tone, and personal preference.
 
Here at Mouqy, we’ve got a huge range for men and women, no matter your style or coloring! Here a just a few of them:
 
joe rectangle tortoise front view

Mouqy’s Joe rectangle tortoise frames.

Mouqy’s Brainy Frames

Mouqy’s Brainy oval black silver frames.

alex square gold front view

Mouqy’s Alex square gold frames.

audrey cat eye purple front view

Mouqy’s Audrey purple cat eye frames.

 

The best lenses are the ones that meet your needs

It’s essential to make sure your eyewear fits not only your lifestyle and style but also your prescription needs.
 
At Mouqy, you can not only order your prescription glasses online, but you can also use Mouqy’s virtual try-on tool to see if your selected frames suit you!

Phoebe Jade

Written by:

Phoebe Jade

Phoebe is a registered nurse, licensed teacher and writer who's passionate about creating content that educates and inspires.

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