Most of the modern smartphones have multiple rear cameras designed for different purposes. You may be familiar with wide-angle cameras and macro lenses, but some phones also have a “depth camera” or “depth sensor.” but what exactly it is a depth camera, and does it really matter?
What is a depth camera?
Depth cameras, also known as time-of-flight (ToF) cameras, are sensors designed to determine the difference between the camera and the subject of an image, usually measured with lasers or LEDs. Time-of-flight technology is used in many different areas where object tracking is important, such as robots that pick up objects in automated factories and in Microsoft’s now-defunct Kinect accessory for Xbox 360 and Xbox One.
Depth cameras on smartphones are not like most other cameras on phones. You can’t take a photo with just the depth camera, like you would with an ultra-wide, macro, or telephoto lens—the depth camera simply helps the other lenses judge distances. It is typically used in conjunction with software algorithms to determine the outline of the subject (a person, animal, or other object) and apply a blur effect to the rest of the image.
Some iPhone models also have a “TrueDepth” camera, which is mainly used for Face ID facial recognition. Apple says in a support document: “Face ID provides intuitive and secure authentication enabled by the next-generation TrueDepth camera system with advanced technologies to precisely map the geometry of your face.” The only time TrueDepth is used for photography is when using Portrait mode on the front camera.
Do I need a depth camera?
So should you look for a phone that has a depth camera? There is a simple answer: no. Dedicated rear depth cameras aren’t found on most flagship-class smartphones, including the iPhone and Samsung Galaxy S devices, because Portrait Mode and similar depth effects can be achieved with other hardware.
For example, the iPhone X and iPhone 7 Plus were Apple’s first phones with portrait mode and didn’t have dedicated depth cameras; the effect was made possible with data from the telephoto and main cameras, combined with a bit of magical software. Apple has continued to use the same technology ever since, with additional effects possible on models with more rear cameras. Samsung briefly included a dedicated depth camera in its flagship phones like the Galaxy S20+ and S20 Ultra, but it was removed with the S21 and newer phones. Just like iPhones, most Samsung devices now use other lenses and software to create a depth effect.
Using other lenses for depth effects has a significant benefit: the other lenses are more useful. As mentioned above, a depth camera can’t actually take photos (that’s why some companies just call it a “sensor” to avoid confusion), it only provides distance data for the other cameras. However, a telephoto or ultra wide angle camera can work as a depth sensor. Y capture photos with their intended purpose. A phone with a regular wide angle lens and a depth camera can only take photos at a so-so distance, with or without depth effect, but a phone with a wide angle and telephoto lens can do the same thing with the addition of improved zoom. .
So if other (more useful) cameras can serve the same purpose as a depth camera, why are depth cameras still prevalent? It is mainly about psychology. The arms race for smartphone photography led to dual, triple or quad cameras being marketed as premium features. Some phones try to include as many cameras as possible, even if they have limited or no real-world use, a tactic especially popular with budget phones.
An example of this trend is the Galaxy A03s, a budget phone from Samsung. It has three cameras, but only the main 50 MP sensor is useful. One of the other lenses is a 2MP depth camera, and the other is a 2MP macro lens, which is too low-resolution to be anything more than a novelty. Swapping both lenses for an ultra-wide or telephoto lens would be more useful, but it would also mean fewer cameras (possibly hurting sales) and/or a higher price.
In conclusion, depth cameras can be useful, but you shouldn’t pass up a phone just because it doesn’t have one. Many phones and tablets can create depth effects using other lenses and software, and mobile editors like Photoshop Express can create a similar (though not as good) look with standard photos.