Ever since cameras became the biggest selling point on smartphones, manufacturers have been putting a lot of effort into improving their quality. At some point, a lot of attention was given to the amount of megapixels a smartphone camera could pack.
In recent years, a new trend has emerged－more cameras. Dual camera smartphones are becoming more and more common but smartphone manufacturers are not stopping there. Triple camera smartphones are on the rise and phones with four or more cameras have also entered the market.
This raises the question…
Why would a smartphone need to have more than one camera?
Multiple cameras mean improved picture quality and optical zoom functionality. Each camera has a lens that can give you either a wide shot or a zoomed-in shot. Some phones have additional cameras that shoot black and white for increased light sensitivity while others offer depth information. Data from the different cameras can be combined into a clear photo with seemingly shallow depth-of-field and good low light capability.
But why not have just one camera that can do it all?
To keep their devices thin, smartphone manufacturers have opted to add more cameras to their phones. Each camera has its own type of lens with its own fixed focal length.
Dedicated cameras such as DSLRs have lenses that can zoom in and out in order to capture a wider shot or get in tighter to a specific area. This can be seen by how the lens barrel protrudes or retracts as the zoom is being adjusted. This is known as optical zoom due to the fact that the glass elements of the lens barrel are physically moving back and forth in relation to each other when zooming in and out. These type of lenses are usually rather large in size but that’s hardly ever an issue in traditional photography.
When it comes to smartphones, though, size matters. Therefore, attaching a variable focal length lens to a smartphone will result in a camera bulge that extends considerably from the phone body. Samsung tried that with the Galaxy K Zoom in 2014 which provided 10x optical zoom but that didn’t prove to be popular.
Lenses and focal length
In order to fully understand why a smartphone would need more than one camera, you first need to understand focal length and its impact on the lens’s angle of view (sometimes called field of view).
Simply put, focal length refers to the distance between the centre of the lens and where light converges on the sensor. This distance is measured in millimeters, e.g. 50mm. Lenses with short focal lengths such as 24mm capture more of a scene and are therefore said to have a wide angle of view. The longer the focal length, e.g. 130mm, the narrower the angle of view and therefore the more magnified or zoomed-in the image to a particular area.
A variable focal length lens is one that changes its focal length as it zooms in or out between a wide shot and a closeup. In DSLR photography, the 18-55mm kit lens is a typical example of such a lens. What those numbers mean is that this lens can shoot as wide as a 18mm lens but when zooming in, the glass elements inside the lens barrel move and narrow the shot to the focal length of a 55mm lens. When the glass moves, the focal length changes.
A fixed focal length lens has no movable glass elements in the lens barrel. This means that you cannot zoom in or out using this lens as it only has one fixed angle of view.
This fixed focal length approach is how smartphone manufacturers keep their devices thin. I guess it makes more sense to them to have multiple cameras with different focal lengths to function independently yet in conjunction with each other through software than to have everything all packed into one large, unsightly camera bump.
What does each camera do?
Camera design differs from manufacturer to manufacturer but a typical single camera smartphone has a wide-angle lens with a fixed focal length. This lens’s short focal length means a wider angle of view which is perfect for shooting things like landscapes, street photography or a large group of people without stepping too far back. Wide-angle lenses allow a lot of light in and have a deep depth-of-field which means everything in your shot remains in focus.
The LG G8 ThinQ has a wide-angle lens with a focal length of 27mm which is more or less standard for this type of lens on most smartphone cameras.
This lens goes even further than a standard wide-angle lens which means you can capture even more of a scene because it has a much shorter focal length and therefore a much wider angle of view. With this lens, it possible to stand at the bottom of a tall building and fit the entire structure in your shot.
Samsung’s Galaxy S10+ has a 12mm ultrawide-angle lens which gives you a really wide 123° field of view.
Unlike the wide-angle lens, the telephoto lens has a much longer focal length which means that instead of getting a shot that captures the entire scene, you can zoom into one particular area. Some smartphones use software to match the data from the other cameras to create a smooth zoom effect as the camera unit switches between the wide lens and the telephoto lens.
The Huawei P30 boasts a telephoto lens with a focal length of 125mm. This means you can zoom in up to 5x without losing picture quality!
A monochrome (black and white) sensor has no colour filter array which means it can capture sharper images than a colour sensor. It also means that the monochrome sensor is more sensitive to light which is good for low light situations. Pictures taken in true black and white (not processed through a filter) are known to be sharp and full of contrast.
Smartphones that have this camera, use the sharpness and contrast information from it and blend it with the image from the colour sensor to create a final colour image with better lighting and sharpness.
And if you’re a fan of black and white photography, it is possible on some smartphones to isolate the monochrome camera and take photos in true black and white.
Time-of-Flight camera (Depth sensor)
A Time-of-Flight (ToF) camera is basically a depth sensor. It shoots out an infrared light and measures how long it takes for the light to reach the subject and bounce back to the sensor. This data is used to create a depth map of the subject and the surroundings.
It is the information from the depth sensor that is used by software to separate the foreground and background and thus create the blurry background bokeh effect.
Not all smartphones have a dedicated ToF camera. Some manufacturers have opted to rather use information from the other cameras in order to figure out the depth in the scene through complex algorithms.
Combinations of cameras
Different manufacturers have their own choices of how many cameras they will put on their smartphone. Not only that, but they also decide which combination of lenses and sensors they want to install.
Some camera combinations are put together to achieve what is said to be “optical focus”. To find out more about optical zoom and how it affects your photos, you can read my article Optical Zoom On Smartphones: What Is It Really?
The dual camera setup has been around for a long time but didn’t really pickup until around 2016. Since then it has become a pretty common feature in a lot of smartphones.
Dual camera smartphones come in a variety of combinations:
Wide + telephoto.This is by far the most popular of the dual camera combinations. It has the advantage of a superior zoom that comes with it and the bokeh effect for portraits. The telephoto lens, however, is usually just slightly inferior and doesn’t really work well in low light.
Wide + monochrome. The combination of data from these two cameras results in pictures that have better colours and more detail with less noise. However, for this to work, both cameras have to be identical which means optical zoom is not possible in this setup.
Wide + ultrawide. This combination aims to give you as wide an area of coverage as possible all in one shot. The resolution on both sensors needs to be similar.
Wide + ToF. Not the most popular of the lot because, even though the depth sensing of this combination is better than that of a single camera, it’s not as effective or practical as the other combinations.
Triple Cameras or more
The most popular and practical combination found in triple camera smartphones is that of the wide-angle, telephoto, and ultrawide lenses. This combination builds on the dual camera setup and opens up a whole lot more possibilities. Not only will your pictures cover a wider area but you can also zoom in to a specific point.
Other combinations of either a wide + telephoto or wide + ultrawide with a monochrome sensor or dedicated ToF camera exist but aren’t as popular.
And just when you think three cameras is enough, quad camera smartphones come into the picture. At this point the wide-angle, telephoto, and ultrawide lenses are a given and then combined with either a monochrome or ToF camera.
However, this is not the given standard. The 5 camera setup found on the Nokia 9 PureView actually consists of two cameras with colour sensors and three cameras with monochrome sensors. This is uniquely different to how other smartphone manufacturers set up their multiple cameras.
The question of whether smartphones really need more than one camera is truly a subjective matter. Sure, single camera smartphones have been taking fairly decent photos for what they are but there’s no denying the difference that two or more cameras can make. That being said, a picture taken by a single superior camera can look better than that of multiple mediocre cameras.
If you’re like me and you buy a smartphone mostly based on the camera, make sure you learn and understand all the specs. Know what you’re looking for in a smartphone camera and go for that. You might just find a dual camera phone that satisfies your needs better than a phone with more cameras that don’t do much.