A third beta of the first major software update to macOS Sierra since its public release last month was seeded this morning to members of the Apple Developer Program. macOS Sierra 10.12.1 beta 3 build “16B2338c” follows beta 2 which was released six days ago, and the first beta that released on September 22, 2016. The latest beta is available through the Mac App Store’s Updates tab on computers running a prior 10.12.1 beta.
Beta 3 focuses on bug fixes and performance improvements, but does not include any new user-facing features. One of the features that macOS Sierra 10.12.1 will enable once it goes live for everyone is support for Portrait albums in the Photos app.
The upcoming iOS 10.1 software update will enable a Portrait feature in the stock Camera app that allows owners of the iPhone 7 Plus to capture DSLR-like depth of field photos by combining sensor data from both cameras.
If you have a developer account, you can grab the standalone macOS Sierra 10.12.1 beta 3 download from the Apple Developer Center.