How Does a Camera Lens Work?

How Does a Camera Lens Work featured photo

If you are a beginner in photography, you probably focus only on the camera and not the lens. You spend time learning all the buttons and settings to capture higher-quality images. However, understanding the lens is also essential if you want to become better at the craft. 

A camera lens is a photography tool that directs light on a fixed focal point. It uses several glass pieces that bend light rays. Each optical element works differently to help you capture a sharp and clear image.

This article covers the structure of a camera lens. We will teach you how each component affects light, and as a result, the final photo. We will also answer frequently asked questions about lenses below.

What Is a Camera Lens?

What Is a Camera Lens

A lens is an essential tool or piece of equipment in photography. Often called the eye of the camera, it allows light to pass through and hit the image sensor. In turn, the sensor records the wavelength of light and forms the image.

The lens guides light in different ways, depending on the camera. For instance, a lens attached to a film camera sends illumination to the film strip. Meanwhile, in a digital camera, the optical glass directs light to a digital sensor. 

What Is the Anatomy of a Camera Lens?

An interchangeable camera lens comprises five main parts—the barrel, focus ring, zoom ring, elements, and bayonet.

The barrel is the physical outer body of the lens. It can use aluminum, stainless steel, or plastic for its exterior construction. This component usually has markings for the lens manufacturer, focal length, aperture range, and other terms (which we will cover below).

The focus ring and zoom ring are located within the lens barrel. The former allows you to adjust the focus area manually. Meanwhile, the latter lets you change the focal length or zoom of the lens. However, it is only present on a zoom lens.

Elements describe the internal individual glass pieces that guide light rays toward the sensor. They come in a convex (curving outward) or concave (curving inward) shape.

Finally, the bayonet refers to the end of the lens that attaches to the camera body. It has different mounts that determine its compatibility with cameras.

What Are the Different Camera Lens Markings?

On the lens barrel, you will find various markings and terms you may be unfamiliar with. Each is a characteristic part of the lens. It can also affect how the camera lens works. 

  • Lens Information – It typically includes the lens manufacturer, focal length, minimum f-stop, and part number.
  • Working Distance Range – Some lenses show the distance range, usually in feet and meters. The infinity symbol is on one end of the scale, whereas the minimum focusing distance is on the other end.
  • Maximum Aperture (f-stop) – It is the largest aperture opening that the lens can offer. It is located on the end of the lens barrel or the front of the lens.
  • Lens Diameter – It describes the distance across the center of the lens. It is expressed in millimeters (mm) with the diameter symbol (Ø).
  • f/# Tick Marks – Older lenses or lenses that enable direct f-number control have an aperture ring. The tick marks help you know where to turn the aperture adjustment ring to achieve a specific f-stop.

How Does a Camera Lens Work?

A camera lens uses various internal glass pieces to focus light toward the image sensor. These elements bend the light direction. At the same time, the lens construction can alter the way illumination hits the sensor. 

Below, we will cover several factors determining how a camera lens affects the final photo.

Focal Length

Focal length is the distance between the lens’ optical center and the focus point, where light rays converge. It is expressed in millimeters (mm).

The focal length determines the field of view or how much of the scene that you see will be captured. It also affects the magnification of the subject.

Smaller numbers, like 16mm or 35mm, represent a short focal length. These lenses have a wider angle of view to capture more of the scene in front of you. They also make the subject appear small.

In contrast, longer focal lengths (large numbers) offer a narrower perspective to show less of the surroundings. They can provide greater magnification.


The aperture describes the lens opening that allows light to pass through and reach the image sensor. It can affect the exposure or the amount of light entering the sensor. It also determines the depth of field or the area in the image that appears sharp and focused.

The lens aperture is expressed in f-stops or f-numbers. A larger number denotes a small opening, while a smaller figure has a larger aperture.

For example, f/2.8 lets more light into the camera than f/16. It also creates a shallower depth of field to isolate the subject from the background.

Almost all lenses list the maximum aperture on the barrel. However, some lenses have two f-numbers expressed in a range. They feature a variable aperture, which changes the lens opening based on the focal length. For instance, an 18-55mm lens has a maximum aperture range of f/3.5 to f/5.6. Shooting wide at 18mm lets you use a large aperture of f/3.5. However, zooming in at 55mm can limit the lens opening to f/5.6.


Light passes through a lens and hits the camera sensor, which processes the final image. However, light enters the glass elements from different angles and directions.

The lens bends the rays and directs them to a single convergent point. This area is known as the focal point.  

The camera lens has a focus ring that lets you adjust the focus area manually. Most lenses also come with autofocus capabilities. They can automatically change the focal point by sending electronic signals to the camera, and vice versa.

Lens Mount

The mount is a mechanical fitting located at the end of the lens. It lets you connect the interchangeable lens to the camera body.

The lens mount differs based on the manufacturer and model. For example, a Canon lens is not compatible with a Nikon camera. The same applies to Nikon lenses because you cannot attach them to a Canon device. 

Lens mounts can also affect several aspects of the glass elements. These include the flange distance, minimum back focus distance, and electric communication.

What Are the Types of Camera Lenses?

What Are the Types of Camera Lenses

Camera lenses have two primary categories.

  • Prime Lenses –  Primes have a single, fixed focal length. Although prime lenses are less flexible, they have a compact and lightweight build. They also tend to have fast autofocus and a large maximum aperture.
  • Zoom Lenses – These types of lenses have multiple focal lengths to let you zoom in or out of the subject. Zoom lenses are more flexible than a prime lens. However, they are larger and heavier.

Both prime and zoom lenses are further divided into different types based on their focal lengths.

  • Wide-Angle Lenses – These lenses have a focal range between 16mm to 35mm. They provide a wide field of view, hence the name.
  • Standard Lenses – Standard lens types offer a focal length from 35mm to 70mm to capture a natural perspective.
  • Telephoto Lenses – Telephotos have a focal length of 85mm to 800mm and beyond. They deliver a narrow view and great magnification.

Some types of camera lenses can introduce different effects to the image. These specialty lenses have different examples. 

  • Fisheye Lenses – These ultra-wide-angle lenses give you a 180-degree perspective. They distort the image to exaggerate the size of the subject.
  • Macro Lenses – These specialty lenses capture images at extremely close distances. They emphasize small details and make them appear larger in the sensor than in real life.
  • Tilt-Shift Lenses – Also known as perspective control lenses, they let you change the position of glass elements with respect to the sensor. They also allow you to alter the plane of focus.

How Does Light Affect Camera Lenses? Other Things to Consider

Camera lenses properly bend light to create a sharp, focused image. However, the internal elements have different builds and designs, depending on the manufacturer. These can affect the direction of light entering the sensor, leading to several optical problems.

Chromatic Aberration

Chromatic Aberration

Chromatic aberration happens when the lens fails to focus the colors within an image to the same convergent point. It can affect some shades more than others, resulting in an unwanted outline on the subject’s edges.

Fortunately, chromatic aberration or color fringing is easy to correct in photo editing software.


Lens distortion occurs when the camera deviates from a rectilinear projection. Rectilinear describes the lens’ ability to retain straight lines within an image.

Three main types of lens distortion often appear in photos.

  • Barrel Distortion – This optical effect makes the lines protrude outward, similar to a barrel. It can magnify the center part of the image while shrinking the edges.
  • Pincushion Distortion – This type of lens distortion makes the lines curve inward. It compresses the middle part of the photo and stretches the edges.
  • Mustache Distortion – Also known as a complex distortion, it combines both the barrel and pincushion optical effects. It is usually common in older camera lenses.

Similar to aberrations, distortions are easy to fix in post-processing.

Lens Breathing

Also called focus breathing, it happens when the lens slightly changes its focal length as you adjust the focal point. It is often a problem in shooting video because the change is very noticeable.

Fortunately, most high-end lenses eliminate lens breathing.

Lens Flare

Lens flaring occurs when excess or unwanted light enters the sensor and scatters randomly. It usually comes from bright lights that shine directly in front of the lens. These include the sun, streetlights, and car headlights, among other illumination.

What Are the Camera Lens Accessories?

Lenses have different accessories that can alter how they work and capture the image.

Lens Filter

Most lenses let you attach a filter, an extra piece of glass, at the front. This filter comes in different types to produce various effects.

  • UV Filters – These protect the lens against bumps, scratches, dirt, and paint.
  • Polarizing Filters – They can add saturation to the image and minimize unwanted reflections.
  • Neutral Density Filters – Also known as ND filters, they reduce the amount of light that enters your lens and enters the sensor. However, they do not alter the color of the final photo.
  • Color Correction Filters – As their name suggests, these filters correct or enhance the color of elements within a scene.

Lens Hood

A lens hood is a tube or ring that attaches to the front part of the lens. It can block light from a certain angle or direction. Hence, it can eliminate lens flaring. 


A teleconverter sits between the lens and the camera body. It has a built-in optical element that redirects light. Doing so can increase the effective focal length of the lens.

However, teleconverters limit the amount of light entering the camera. They can also lead to slower autofocus performance and increased risk of camera shake.


A camera lens is one of the most important tools in photography. Understanding how it works is essential to taking great photos.

A lens uses several glass pieces to guide light toward the image sensor. Each glass element affects the direction of light and the final photo, as we thoroughly covered above.

Do you have more questions about camera lenses? Feel free to reach out via our contact page!