https://www.theverge.com/2018/10/11/17963172/samsung-galaxy-a9-release-date-news-features-four-cameras

Samsung has just announced the Galaxy A9, a mid-range smartphone notable for featuring a grand total of four cameras on its back. The handset is part of a new strategy from the company in which it’s attempting to introduce features on its mid-range devices first in order to appeal to developing markets and a younger audience in the West who are priced out of flagship devices.

Each of the four cameras on the rear of the device serve a different purpose. The first is the device’s main 24MP f/1.7 camera, the second is an 8MP f/2.4 camera with an ultra-wide 120-degree lens, the third is a telephoto f/2.4 lens with 2x optical zoom backed by a 10 megapixel sensor, and the fourth is a 5 megapixel f/2.2 camera that enables depth-of-field effects.