Affiliate Disclosure: By buying the products we recommend, you help keep the site alive. Read more.
Gone are the days where people had to lug around enormous cameras with short battery lives to take high-quality photos. While they can’t beat a dedicated camera, smartphones are versatile, portable, and can take beautiful, high-resolution pictures.
If you’ve bought a new smartphone in the last few years, there’s a good chance that it has two or three (or four!) cameras on the back. What do these additional cameras do? The uses of these cameras vary from phone to phone.
In this article, we’ll be listing down the types of secondary lenses and how they’re making your smartphone camera more powerful.
A Brief Explanation of Focal Lengths
If you’ve ever been in a camera store, you’ve probably seen the terms “10mm” or “35mm” thrown around to classify lenses or describe how shots are taken. These terms refer to focal length, which is the distance between the camera’s lens and the image sensor.
Simply put, the focal length determines two things: how much it captures of a scene, and how much it magnifies a part of what you see.
A camera with a short focal length allows you to capture a wider image, while a long focal length allows you to magnify details from far away. Lenses for DSLR cameras normally have a range of focal lengths that they can use, such as 18mm-55mm or 9mm-18mm.
The Telephoto Lens
There are two ways that a camera can zoom into a faraway subject. Many smartphones use digital zoom, which is simply enlarging a part of the captured full-resolution image. This often results in a significant loss of detail, especially at long distances.
Dedicated cameras use optical zoom. This method utilizes a telephoto lens, which lets you raise the focal length of your captured image so you can zoom into a subject without compromising the image quality.
While a lot of people would like their phones to have better zoom capability, smartphone manufacturers can’t include the kind of telephoto lenses that are in bigger cameras. Those lenses would either make devices much thicker or add an unsightly bump at the back.
Many smartphones, such as the iPhone Xs and Galaxy Note 9, use a second lens with a higher focal length. When you use your iPhone’s 2x Optical Zoom function, what it’s really doing is switching to the other lens to enlarge the image without a noticeable dip in quality.
Some phones like the Google Pixel 3 use advanced image processing software to digitally zoom into photos without a secondary lens. How well this works depends on the software of the camera app, but the results are often comparable to photos taken with an optical zoom.
Other phones, such as the upcoming 48 megapixel Xiaomi Redmi, use cameras with a high megapixel count to improve their zoom.
Example phones: iPhone 8, X, and Xs, Samsung Galaxy S9 and Note 9, Huawei Mate 20 & P20
The Wide-Angle Lens
There are also times where you have to be able to capture more of the subject in an image. For example: if you’re taking a photo of a sunset against the ocean or the skyline of a city. In these situations, you need a camera that has a lower focal length than usual, also known as a wide-angle lens.
Unlike zoom, there is no way to digitally recreate a wide-angle shot. Therefore, wide-angle lenses are an especially powerful addition to a camera’s arsenal. Before Huawei released the Mate 20, the LG flagships were the only smartphones that included wide-angle rear cameras.
Even before wide-angle cameras were added to the rear of phones, they were already being used in front-facing cameras. They can expand the number of people that can fit in a selfie. Despite having a single rear camera, the Pixel phones still include a front-facing wide-angle lens.
Examples of Phones: Huawei Mate 20 Series, LG V40 ThinQ
The Depth Sensor
Nearly all smartphones released in the last few years have an in-built portrait mode on their camera apps. Portrait mode lets you create a “bokeh” effect by blurring the background while the foreground stays in focus. In order to help these phones create that effect, some have a camera that analyzes depth information.
On mid-range and budget phones, this type of secondary camera normally has a lower resolution than the primary camera, such as 2 or 5 megapixels. They work by detecting where the foreground ends and the background begins. This technology is commonly referred to as edge detection.
Many other types of secondary lenses double as a depth sensor. The OnePlus 6T comes with an additional 20MP snapper that improves the quality of the digital zoom, while also improving photos taken in portrait mode. The iPhone Xs uses its telephoto lens to collect depth information as well.
Examples of Phones: Pocophone F1, Motorola Moto G6, OnePlus 6T, Vivo V9 & V11
The Monochrome Lens
In certain situations, black and white photos can be more dramatic and eye-catching that colored photos. However, most smartphone cameras are limited to filters that turn photos black and white after they are taken. A dedicated monochrome lens can snap pictures in true black and white, which makes images much more striking.
Since Huawei first announced a partnership with Leica, all of their flagships (including the Mate 10 and the P20) feature a dedicated monochrome lens that allows for shooting true black and white photos. It has since been discontinued and replaced with the wide-angle lens on the Mate 20 Pro.
The monochrome lens has also made its way into other devices, including Motorola’s flagships and the Sony Xperia XZ2 Premium.
Photos that are taken in true black and white tend to have stronger contrast than those that pass through a filter, with deeper shadows and brighter highlights. Also, the monochrome lens increases the amount of light comes in to improve the detail and vibrancy of colored photos taken with the main lens.
Examples of Phones: Huawei P20, P10, and Mate 10, Sony Xperia XZ2 Premium, Moto Z2 Force
Cameras With 2, 3, 4 Lenses and Beyond
In addition to the ones mentioned above, several niche phones have interesting uses for their dual camera setups. The most notable one is the Huawei Honor View 20 that came out in early 2019. It features a unique time-of-light camera that is used to capture 3D images.
Meanwhile in 2018, Samsung released the Galaxy A9, a mid-range device that is the world’s first quadruple rear camera smartphone. In addition to its primary lens, it features a telephoto lens, a depth sensor, and a wide-angle lens.
If the continuously increasing number of cameras on phones is any indication, we should be seeing more quadruple camera setups soon.
Mobile Cameras Keep Getting Better
Whether your phone has four rear lenses or a single rear lens, the quality of photos that it’s taking are much better than phones from just a few years ago.
Which phone should you get? It depends on what you want to do. Do you take many photos of big cityscapes or group shots with a lot of people in them? Then a wide-angle camera works wonders.
Do you fill your Instagram feed with dramatic, striking pictures of urban life? A monochrome lens will be very useful. There’s a great smartphone camera for every use case and every budget.
At the end of the day, the quality of a picture depends just as much on the photographer as it does on the camera. If you want to improve your mobile photography skills, check our tricks to improve smartphone photography.