As part of its efforts to move more and more of non-critical functionality to Google's app market system, Sony has published its Background defocus camera mode on Google Play Store. This will make it easier for the manufacturer to iterate over and push changes to the app as fast as it can.
Background defocus made its debut in the camera app of the newly unveiled Xperia Z2. This particular effect, which emulates a shallow depth of field, seems to be getting quite popular, as more and more manufacturers are advertising it as one of the fun ways to use a mobile camera. The effect is mostly applied after the shot is taken, blurring the background and bringing more focus to a foreground object.
With the app now on Google Play Store, Sony has decoupled the feature from the Xperia Z2's firmware and has made it available for other Xperia devices as well. The mode still functions the same way and no new features were added. The mode has to be chosen from with the Camera app and adjusted after the photo has been taken. Sony suggests a distance of about 15 - 45 cm for the best effect.
The Background Defocus effect was actually already ported for other Xperia devices before but now it is official and comes from Sony directly. It still works only on Xperia smartphones, of course, and such devices should be running Android 4.2 or higher to be compatible.
Download: Sony Background Defocus on Google Play Store