Picture quality can be the difference between a prized shot to last a lifetime and a pixelated mess that's quickly deleted.
Deciding how and when to zoom can make or break an image, and with mobile phone cameras needing to find workarounds to compete with dedicated cameras, there's a lot more to consider.
We explain how to make the most of a phone's zoom functions and demystify manufacturers' often grandiose claims around phone camera and digital zoom capabilities, to help you choose the right settings to achieve that perfect shot.
But not all zooming is created equal. There are actually two types of zoom that any digital camera can do:
Mobile phones, which now come with lots of cameras in small clusters, employ both types of zooming in their native camera app. Phone camera lenses can't extend like digital cameras do, so instead you will have two, three or even four lenses with different focal lengths built into the phone to create different levels of optical zoom.
Much of a phone's zooming potential is usually digital. But while digital zoom can be a nifty way to create a magnified picture without needing a specialist lens, it also creates irreversible quality loss.
Anybody buying a mobile phone or fixed-lens camera, such as a compact camera or a bridge model, should be wary of this.
Digital zooming is when a camera continues to pull closer to an image despite surpassing the maximum focal length of its longest lens.
Digital zooming is essentially cropping the margins of your photo and enlarging the image to fill the frame, making it look like the camera zoomed in.
This causes image quality to nosedive. To compensate for this, manufacturers have created algorithms which artificially enhance the image to make it look better, also known as upscaling.
When upscaling an image using software, your phone may sharpen it or even look at the pixels in it and inject different pixels into parts of your photo to make it look better (known as interpolation).
A particularly complex form of digital zoom, sometimes called ‘hybrid zoom’, uses the same techniques but with added steps, such as having every lens in the camera taking an image at once and then merging them together to make a cropped, upscaled image look better.
This is the two halves of digital zoom: cropping and processing. Neither of these happen with traditional optical zooming.
This is where your camera lens is physically closer to your subject. There’s no quality loss when you bring your lens closer to your subject.
The drawback is that optical zooming requires your lens to extend outwards and this is only feasible up to a certain degree for mobile phones.
To compensate, most mobile phones have clusters of different cameras together. Each one has a different lens, so you can swap between less and more zoomed without lenses actually moving.
High-end digital cameras can zoom more freely, but you need to spend a lot of money to buy a lens that has a high focal length. This is called a telephoto lens and it can have a focal length of 60mm, or even longer.
Mobile phones are ultra-compact with small lenses locked behind glass screens made of extremely durable glass, like sapphire or Gorilla Glass.
A lens that extends outwards extensively simply doesn’t fit into the design of a modern smartphone.
Attempts have been made in the past to make camera phones that work like compact cameras, most notable the Samsung Galaxy S4 Zoom.
This large smartphone had a large lens jutting out its back. It has a shutter button on its shoulder and it was 15mm thick.
It didn’t catch on - and looking at it, it’s easy to see why. Phones have good cameras integrated into them now, but it’s unlikely they’ll use the same hardware as dedicated cameras anytime soon.
Undoubtedly - but it’s best to know you're using it. If the quality of your photo is ruined because you used digital zoom extensively, you’ll never be able to restore it.
In contrast, if you take a picture without stretching it out, you can crop it later and zoom in using an image editor without losing the quality of the original image.
But there are scenarios where it’s worth using:
But there are also times where it’s worth sticking to your maximum optical zoom length:
If you’re buying a mobile phone, the good news is that you can always find out how much of a camera’s zoom is optical and how much is digital by looking at the specification.
We found that the biggest phone manufacturers were consistent when it came to publishing optical zoom options, even where further magnification is possible with digital zooming.
Some manufacturers have taken to a new term called ‘hybrid zooming’. This has a meaning that’s difficult to pin down, but it’s essentially a form of digital zooming.
Hybrid zooming can involve more complexity than digital zooming, such as the camera taking multiple images with its different lenses and compositing them, but specifics vary across manufacturers.
But in essence, it is fundamentally different from optical zooming and if you want the best form of quality for your photos, you should stick to heeding the focal lengths of the lenses on the phone.
We found that manufacturers tend to create new terminologies for zooming when trying to sell new products.
The S20 and S20+ have something called ‘Space Zoom’ which is ‘the combination of 3x Hybrid Optical Zoom and 30X Super Resolution Zoom’. In other words, the maximum optical zoom and then digital zooming afterwards.
There’s no doubt that upscaling algorithms are getting better. But when it comes to knowing what hardware you’re buying, the actual optical length is still the best and most dependable guide.
Although manufacturers usually make these distinctions in their marketing, it remains the case that camera apps obscure the difference between optical and digital zooming.
The iPhone 13 family, for example, allows you to switch between three lenses when you open the camera app: 0.5X, 1X and 3X magnification (a wide-lens, a human field of vision, and a close-up perspective).
But by using your fingers to zoom manually, you can scroll up to as much as 15X magnification without any notice that you’re effectively just cropping an upscaled image obtained with the 3X lens.
This means that most of the possible zooming available on the phone is artificial with no indication when you’ve swapped from optical to digital zooming.
If you care about your phone’s camera performance, look for these things: