Demystifying smartphone camera jargon

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The technology industry is rife with acronyms, jargon and specialist terms that can be overwhelming for newcomers. Photography is no different. In fact, sometimes it can be even worse, and just like the tech sector, often the things we’re told we’re meant to be paying attention to aren’t in fact the ones that really matter. So here’s Stuff‘s guide to the terms you’ll see bandied about, and which of them actually matter.

Megapixels

Until fairly recently, smartphone makers and camera makers alike would trumpet how many megapixels their cameras offered as though more always meant better. Thankfully, even marketers are beginning to move away from perpetuating this myth. Megapixels are an indication of how many individual pixels a camera sensor has, expressed as its area (the number of pixels across, multiplied by the number of pixels down).

Sure, you’ll be able to make a bigger print of a 12MP photo than a 2MP one, but even a 6MP camera can manage A3 prints. And how often are you printing your pictures anyway? What’s far more important than the megapixel count is how big each pixel is, and how big the overall sensor is. That’s why full-frame DSLRs (where the sensor is the same size as a piece of 35mm film) tend to cost more than cameras with smaller sensors (like APS-C) and tend to produce better pictures in low-light — because the sensor has a bigger surface area it can capture more light than a smaller one.

So don’t worry about megapixels, any recent high-end smartphone certainly has enough of them. Instead, take a look at pixel and sensor size.

Aperture

The aperture of a lens controls how much light passes through it. They’re the curved blades you can see if you peer down a camera lens. Aperture is expressed as f1.4, f2.8, f5.6 etc. (where each f-stop, as they’re known, in this example lets in half as much light as the previous one, so f2.8 lets in half as much light as f1.4). Counter-intuitively, the smaller the f-stop number the wider the aperture. So f1.4 is really wide open, while f16 is a really small aperture.

Most zoom lenses for DSLRs or mirrorless cameras have a variable aperture, which means the maximum aperture isn’t the same when the lens is wide as when it’s zoomed (you usually lose a few f-stops towards the long end) like on an 18-55mm/f2.8-5.6 kit lens. Prime lenses, meanwhile, like a 50mm/f1.4 can’t be zoomed but tend to have wider maximum apertures. And fixed aperture zoom lenses (like a 70-200mm/f2.8) can manage the same maximum aperture at any focal length — and tend to be big, heavy and expensive as a result.

A fast aperture also allows for subject isolation (where the subject is sharp but the background is blurry), which is why fast prime lenses are so popular with portrait photographers. It’s also part of the reason why modern smartphone cameras can achieve the same effect (more on this later). Most smartphones have a fixed aperture, with the notable exception of the new Samsung Galaxy S9 and S9+ that have a variable aperture than can switch between f1.5 and f2.4.

ISO

In the days of film cameras, ISO was a measure of a particular roll of film’s sensitivity to light and applied to the whole roll. So, if you wanted to shoot in low-light you’d want film with an ISO of 800, 1600 or even 3200. Meanwhile, for shots in broad daylight you’d want film with an ISO of 100 or 200. Of course, that meant you couldn’t change ISO until you changed film. Today, thanks to the wonders of digital photography, we can adjust the ISO setting between every shot.

In auto-mode smartphone cameras and DSLR or mirrorless cameras will choose the optimal ISO setting automatically, but many smartphones offer “pro controls” that let you adjust ISO manually, and any decent DSLR or mirrorless camera will have a manual ISO option, too. Be warned, though, the higher the ISO the grainier the shot will look, so don’t get too carried away, unless that grainy film look is what you’re after, of course.

White Balance

Like ISO, most cameras will adjust white balance automatically, but you can fiddle with it manually to achieve different colour effects. White balance concerns a camera’s ability to replicate white (and, hence, other colours) accurately for the particular lighting conditions. Different types of light create different colour casts, so sunshine tends to be warmer (more orange) than cold fluorescents (more blue), for example. White balance let’s you tell the camera how to compensate for the colour cast of the lighting conditions you’re in so your photos look natural (or don’t, depending on the effect you’re trying to achieve).

Digital vs. Optical Zoom

Optical zoom means the lens physically adjusts to get you closer, which is why compact cameras with “3x optical zoom” tend to have a camera lens that protrudes from the camera body and actually moves (some cameras manage to move the lens in the body, though). The result is the same image quality whether you’re zoomed or not.

Digital zoom means zooming in on the existing pixels, which is why when you zoom to 10x on your smartphone the picture looks terribly grainy. As a general rule, digital zoom is to be avoided. You may as well crop an unzoomed picture, because that’s all digital zoom is doing anyway.

Dual camera

A growing number of smartphones now include two rear cameras, and different manufacturers have gone for different setups with the secondary camera to achieve different things. Samsung, Apple, OnePlus and others make their secondary camera a telephoto (or zoom) lens camera, which means you can get closer to the action without resorting to digital zoom.

LG goes the other way and uses the secondary camera on its phones to offer a wider-than-normal field of view. Huawei, meanwhile, makes its secondary camera the same length as its primary one but opts for a monochrome sensor. It claims that this allows for better contrast in pictures by using software to combine the best of the colour and black-and-white shots in one.

Bokeh

Bokeh is the Japanese term for the soft, blurry, out-of-focus bits of an image. Prized by portrait photographers for keeping the subject crisp while the background gets dreamy, until recently managing this effect required a high-end camera with a lens with a fast aperture stuck on it. Now, thanks to dual cameras and software wizardry, many flagship mobile phones can achieve it, too. Depending on which smartphone brand you look at you’ll find this ability to create bokeh called “portrait mode”, “live focus” or “selective focus”. Some brands will let you adjust the intensity of the effect and some will also let you adjust it after the fact not just when you’re taking the shot.

Slow motion

Conventional video tends to be shot at either 24 frames per second (fps) or 30fps (or somewhere in between in the case of a standard called NTSC). Slow motion video requires far more frames in order to create the slowed-down effect. The more frames a camera can capture per second the slower the effect. Many smartphone cameras’ slow mo frame rates top out at around 240fps, but Samsung and Sony both make smartphones that are capable of an impressive 960fps (albeit only for a few seconds at a time on account of how much data has to be captured and processed at high frame rates).

The TL;DR version: Megapixels don’t matter, sensor and pixel size does, digital zoom is meaningless, and good slow mo needs lots of frames. When in doubt, set your camera to pro or manual mode and experiment — you can always restore the default settings if things go awry and your pictures start looking like a drunken artificial intelligence painted them with a Vienna sausage.

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