When Apple unveiled the iPhone 7 Plus earlier this month, it introduced a depth-of-field camera trick that's exclusive to the device.

The feature, dubbed Portrait mode, wasn't quite ready for release when iOS 10 started rolling out last week. However, iPhone 7 Plus owners can now test the new feature in the public beta of iOS 10.1, which released on 22 September for anyone enrolled in Apple's public beta programme. It's free and easy to join the programme. Pocket-lint explained how to become an iOS 10 beta tester here.

The developer version of that beta went live yesterday, but of course, you must be a developer to get that up and running on your phone. Still, both betas includes the new camera mode, which is designed to mimic the kind of shallow depth of field you see in images taken with a high-end DSLR. In other words, these types of images usually have a front subject that stands out over a blurred background.

In addition to the usual wide-angle lens, a telephoto lens is located on the rear of iPhone 7 Plus. Apple has devised a way to use both lenses at the same time to mimic depth of field when taking portrait shots. To use the new mode after installing the iOS 10.1 beta, go to Apple's Camera app, then slide over to the Portrait mode, and the mode should prompt you to move back.

When you capture in Portrait mode, the camera snaps two photos: one regular and one with blur applied to the background. Apple's built-in image signal processor scans the scene, then applies machine-learning techniques to recognise people in the image, and ultimately creates a depth map using the device's two cameras, which results in an image where the people are in focus while the background has a bokeh-like effect.

Apple previously said Portrait mode would roll out in an official update scheduled to hit consumers' phones "later this year".