Lens aperture is increasingly up there with megapixels when it comes to the camera specifications that smartphone makers like to boast about, but what exactly do those numbers mean? Here we look at what aperture is, how it works, and what it means to your smartphone photography.
Aperture is essentially an opening of a lens’s diaphragm through which light passes. It works much like the iris and pupil of an eye, by controlling the amount of light which reaches the retina. A bigger aperture hole lets your smartphone camera sensor gather more light, which it needs to produce quality images.
The size of a lens aperture is described by its F-number, which is calculated using the lens focal length to the diameter aperture. As such, a larger F-number refers to a smaller hole, and therefore less light getting through. This is why smartphone camera manufacturers brag about larger apertures, with smaller F-numbers.
As you move along the F-stops F1.4, F2, F2.8, F4, F5.6, F8, and so on, the aperture halves (half the amount of light passes through) on each stop.
Now we know what the aperture is, and how the numbers work, we can start looking at what it means to photography. In cameras where you can alter the aperture, this allows you to creatively control things such as the depth of field (how much of the photo is in focus) and the shutter speed you can shoot at.
Selecting a larger aperture (remember that’s a smaller number), will give a shallower area of focus. For example, if you want a sharp subject and a blurred background, you might want to shoot at F1.8, but if you want the background sharp too, you might be better with an aperture of F8. Larger apertures can also be used to let you freeze action better by shooting at faster shutter speeds.
While this is all well and good, for DSLRs, mirrorless cameras, and higher-end compacts, the vast majority of smartphone cameras don’t actually allow you to change the setting and have a fixed aperture. Also, because of the wide-angle lenses and small size image sensors in most smartphones, you’d struggle to shoot with a shallow depth of field unless taking a close-up anyway.