This is how the variable aperture of the Galaxy S9 works12
Samsung's Galaxy S9 and S9+ have an aperture that can go from record wide for a phone f/1.5 down to f/2.4, depending on the scenario, which is important for extreme low-light shots, or recording high frame rate videos. Thanks to Zack Nelson from JerryRigEverything, and his phone torture chamber, we now know how the system works, too. Upon disassembling the Galaxy S9, he played around with the camera a bit, pushing against the shutter, and found a small lever on the side that actuates the opening and closing, as you can see above. The mechanics of it are pretty breathtaking, considering how confined is space inside any modern smartphone, so hopefully Samsung will keep perfecting and experimenting with variable aperture cameras in the Galaxy line.
Motion regime, and the aperture to match. This wider f/1.5 aperture comes into play also when shooting in low-light. When the environment is not well-lit, a camera with a fixed aperture is forced to rely on ISO and shutter speed controls to ensure proper exposure of the scene.When shooting at high FPS, the camera shutter needs to operate at an extremely high speed, which results in less light captured by the sensor. This makes shooting slow-mo videos in darker environments an exercise in frustration, especially when it comes to smartphone cameras, so Samsung equipped the S9 with Super Slow