Over the past year or so, an increasing number of flagship phones have added a second rear camera. Why is this? Well, there are a few reasons.

Portrait Mode

Portrait Mode is a term used by both Apple and Android manufacturers and can be used when a portrait photo, usually of a person, is taken. One camera focuses on the subject of the photo, while the other focuses on the background behind the subject. Each camera takes their own photo simultaneously. Software is then used to combine data from both photos and blur the background to give the photo a DSLR effect.

However, it should be noted that a similar effect can be achieved with a singular, dual pixel camera. In this instance, the camera takes a photo of a subject then quickly refocuses and takes a photo of the background. The two photos are then combined with software. This is the approach used by Google’s Pixel 2 and Pixel 2 XL.

Zoom

Pretty much all phones use digital zoom instead of optical zoom. This is when the image is digitally cropped, rather than being magnified mechanically by moving a lens closer to or further away from the cameras sensor. Digital zoom is generally undesirable, as the quality of the resulting images is significantly reduced. Each camera in a dual lens phone has a different focal point, meaning that one of the cameras has a wide focus (much wider than a typical phone camera), while the other is a closeup focus. Software can be used to combine each camera to create a convincing optical zoom effect.

Differentiation

Smartphone manufacturers are always looking for new ways to differentiate their new generation of products from their previous generation. Most changes are internal improvements (such as increased processor speed), and are often unnoticed by the consumer. Adding a second camera to the rear, however, is quite hard to miss.

Additionally, it is used by some manufacturers as a “premium feature only available in [the biggest, most expensive model]”. This results in many consumers spending additional money on an already expensive device.

What are the drawbacks?

Photos taken in a dark environment with a dual camera phone are often inferior when compared to a single camera phone. Also, since most manufacturers are only just releasing their first dual lens phone, the software is less than perfect, meaning that some photos may not turn out how you would like (e.g. there may be some artefacts), although many of these issues will likely be resolved with future software updates.

What’s your opinion of dual camera phones? Are they useful, or just a marketing gimmick?