By far the S9’s biggest upgrade is the rear camera. This phone might have the same 12MP pixel count, dual-pixel autofocus and optical image stabilisation as last year’s model, but you now get a variable aperture as well. What does this mean? The S9 can adjust how much light it lets in according to where you’re snapping. So low-light shots are markedly clearer and sharper than the Galaxy S8 and its fixed aperture. Use f/1.5 in brighter conditions, though, and it isn’t hard to spot a lack of sharpness at the edges of the frame.