Chris Velazco/Engadget

The paired sensors are available only on the larger S9+, though, so fans of daintier handsets might have to make do with slightly reduced image quality (more on the specific differences on that front later).

A dual-lens setup is only one of a slew of new camera features for the S9 and S9+. They both come with something the company is calling "Dual Aperture" which sounds like it allows for two openings on a single lens. But really, it's one aperture that jumps between two f-stops -- f/2.4 and f/1.5. That last one is the widest aperture on a smartphone yet -- the record was last held by the LG V30, with its glass lens reaching f/1.6.

While the mechanical shutter is on both phones, the S9+ only has it on the primary (wide-angle) lens. The shutter switches between the f-stops automatically by default, jumping to f/1.5 when the phone detects low-light conditions and f/2.4 in bright scenes. You can also manually control it in the camera's Pro mode, but you can't select any f-stops between the two -- your only options are f/1.5 and f/2.4.

Still, the wide max aperture helps the S9 and S9+ let in more light, which makes for brighter and clearer images in the dark. At our demo, Samsung showed off how well this worked on a model scene encased in a blackout cylinder. I peered through the dime-size hole at the top and barely made out a circle in the middle of an otherwise pitch-black setting. After placing the S9's lens on the cylinder, I clearly saw that it was actually a traffic circle, surrounded by houses and trees.

Gallery: Samsung Galaxy S9 and S9+ camera samples