Lens or lense?

What is the difference between lens and lense?

A “lens” is any curved, transparent optical device that transmits and focuses light to develop a clear image of something. Common examples include the transparent glass or plastic eyepiece of glasses, sunglasses, or even microscopes. 

Writers commonly mistake “lense” as an acceptable spelling variant of “lens.” To use the noun correctly, use “lens” for the singular noun and “lenses” (with an -es-) as the plural form. 

Correct singular form: 

“The explosion cracked the lens of his safety goggles.”

Correct plural form: 

“The explosion cracked his safety goggle lenses.”

What does lens mean?

The noun lens (plural lenses) commonly appears in the topic of “optics” (vision) to describe a piece of transparent material that transmits and focuses light to produce clear images (e.g., contact lens, microscope lens, or camera lens), or protects the eye lens from outside damage (such as safety goggles or sunglasses). 

Sentence examples:

• “The eye lens — the clear part of the eye that helps focus light or images on the back of the eye—has a unique structure and is vulnerable to damage.” — Forbes
• “Most people will get presbyopia, an inability to focus on close-up objects, starting in their 40s, when the eye’s lens gets less flexible.” — Wall Street Journal
• “Resting on his nose are a pair of oversize sunglasses with splatter-painted red, white, and blue frames and a mirrored lens that covers his face like a windshield.” — Outside Magazine
• “Easley shoots with a 1,200-millimeter telephoto lens, but even a 100-millimeter lens will do.” — The New York Times Magazine
• “The cameras are fine and you get plenty of choices, including a wide-angle, zoom, and an ultra-wide-angle lens for fitting more people into a shot.” — CNBC

Alternative meanings of lens

There are times when a “lens” is a device that directs and focuses non-light forms of radiation, such as electrons, sound waves, and radio microwaves. 

For example,

• “… an acoustic lens narrows sound waves to a precise spot – as tiny as a millimeter across – to modulate activity in the brain.” — Exponentially More Stories
• “Researchers theorized ptychography in the 1960s and conceived its use to overcome electron lenses’ limits in the 1980s.” — Scientific American

Since a lens is a convex shape bound by the endpoints of two circular arcs, it’s not uncommon to see the term used for an object with a similar “lune” shape. 

For example,

• “True to their name, lenticular clouds are lens-shaped, and they’re also often compared to UFOs or stacks of pancakes.” — Mental Floss

Likewise, we can use lens as a metaphor to describe something that influences or aids one’s perception and comprehension of something. 

For example,

• “Critical race theory is a way of thinking about America’s history through the lens of racism.” — AP News
• “‘A lot of parents have expectations, but they’re not educators, they don’t have the same lens to use to say that’s actually a developmentally appropriate behavior.’” — The New York Times

Etymology of lens

According to Lexico, the word lens arrived in the English language in the 17th century from Latin lentil–– a name that should be familiar for any fans of legumes (Lens culinaris). As the story goes, the word lens arose because of its similarity to the edible seeds, which come from the plant genus Lens.

Understanding different types of lenses

When describing the anatomy of the human eye, the “lens” is the transparent, biconvex area behind the iris (eye color) and pupil (the center of the eye that appears as a black hole). The lens’ spherical body consists of rod-shaped ectodermal cells that alter their focal length in response to the amount of light absorbed onto the retina. 

Abnormal eyesight requires corrective lenses such as:

• Prescription eyeglasses and/or sunglasses
• Contact lenses (filmy lens inserted on the eye surface)
• Monocle (one eyeglass held up by eye muscles)
• Intraocular lens (an implant that replaces a damaged lens or a removed cataract). 

The lens of an optical instrument

When referencing optical devices like corrective lenses, microscopes, binoculars, camera lenses, or a magnifying glass, a “lens” is a curved piece of glass or transparent material that concentrates or disperses light rays to make objects appear larger, closer, or smaller. 

The word lens often denotes a “simple” or “compound lens,” but these lenses are all different. A simple lens consists of one transparent material and spherical shape, while a compound lens is the arrangement of several simple lenses (elements) mounted together on a common axis. 

Types of simple lenses include: 

• Biconvex: convex on both sides. 
• Plano-convex: convex on one side, flat on the other (used for magnifying glasses).
• Positive meniscus: convex on one side, slightly concave on the other. 
• Negative meniscus: convex on one side, more concave on the other. 
• Plano-concave: flat on one side, concave on the other. 
• Biconcave: concave on both sides. 

Convex-concave or meniscus-shaped lenses are the most common type of lens used to correct eyesight. Specific types of lenses found in corrective eyewear include: 

• Converging lens: a type of concave lens that causes parallel light beams to spread out into a wider arc (used to treat nearsightedness or “myopia”).
• Diverging lens: a type of convex lens that concentrates light beams to focus on a specific point (helps correct farsightedness or “hyperopia”). 
• Toric lens: a cylinder-shaped lens that focuses or expands rays of light within a single axis (helps treat astigmatism). 

Compound lenses appear in optical devices and electronic equipment like camera lenses, microscopes, binoculars, and telescopes, and they function to increase magnification, reduce aberrations from single lenses, and produce an upright image. 

When using devices with compound lenses, you might come across the following terminology:

• Ocular lens: the eyepiece attached to optical devices to magnify the image of something. 
• Anastigmat/anastigmatic lens: a type of camera lens that corrects topical aberrations such as astigmatism, coma (comatic aberration), and spherical aberration. 
• Optical condenser: a type of optical lens that focuses a divergent beam of light to illuminate a particular object. 
• Objective lens: the outermost lens that focuses light from an object to produce a real image (with various magnification). 

Additional reading

If you enjoyed learning “lens vs. lense,” be sure to check out The Word Counter’s other optical-related grammar lessons, such as:

• Concave vs. convex?
• Macro vs. micro?
• What Does Bird’s-Eye View Mean?
• What Does Beauty Is in the Eye of the Beholder Mean?
• What Does Hindsight Is 20/20 Mean?

Test Yourself!

Test how well you understand the difference between lens or lense with the following multiple-choice questions. 

1. True or false?: “Lense” is an American English spelling variant, while British English prefers “lens.”
   a. True
   b. False 
2. Which of the following are alternate spellings of singular “lens”?
   a. Lense
   b. Lenses
   c. Lenzes
   d. None of the above
3. _________ is the plural form of lens?
   a. Lensi
   b. Lens
   c. Lenses
   d. Lense
4. The word lens does not describe _______________.
   a. A part of human anatomy
   b. A biconvex transparent body
   c. A convex lense
   d. A transparent, biconvex lens
5. Which of the following objects would have a lens?
   a. A specific type of evaluation
   b. The eyes of human beings
   c. Spherical glasses
   d. All of the above
6. Which of the following does not use the correct singular or plural noun?
   a. “The eye illustration shows a damaged lens.”
   b. “Here are some of the most expensive camera lense in the world.”
   c. “The regular surfaces of eye lenses are convex and clear.”
   d. “The eye exam determined that both lenses are in good shape.”

Quiz Answers

1. B
2. D
3. C
4. C
5. D
6. B

Sources

1. Anderson B. “EXPLAINER: So much buzz, but what is critical race theory?” AP News, apnews.com, 24 June 2021.
2. Blaustein, A. “See the Highest-Resolution Atomic Image Ever Captured.” Scientific American, scientificamerican.com, 28 June 2021.
3. Chittum, M. “New Fralin Biomedical Research Institute faculty member to advance addiction, pain research with focused ultrasound.” Exponentially More Stories, Virginia Tech, 9 Aug 2021.
4. “Contact lens.” The Merriam-Webster.com Thesaurus, Merriam-Webster Inc., 2021.
5. Gutoskey, E. “8 Strange Cloud Types and What They Mean.” Mental Floss, mentalfloss.com, 9 Aug 2021.
6. Harris, T. “Cataracts: What Are They & What Causes Them?” Forbes, forbes.com, 23 Aug 2021.
7. Haselton, T. “It’s time to take Samsung’s folding phones seriously.” CNBC, cnbc.com, 26 Aug 2021.
8. Kaysen, R. “Learning Pods Show Their Cracks.” The New York Times, nytimes.com, 22 Dec 2020. 
9. “Lens.” Cambridge Dictionary, Cambridge University Press, 2021.
10. “Lens.” Lexico, Oxford University Press, 2021.
11. Megroz, G. “Pit Viper’s Formula for Success: Irreverence, Safety Glasses, and Rob Gronkowski.” Outside Magazine, outsideonline.com, 23 Aug 2021.
12. Reddy, S. “The Crucial Years for Protecting Your Eye Health.” Wall Street Journal, wsj.com, 6 May 2013. 
13. Wollan, M. “How to Photograph the Moon.” The New York Times Magazine, nytimes.com, 22 June 2021. 

Photo contributors: David Travis (@dtravisphd) and Harpreet Singh (@harpreetkaka) on Unsplash