Mobile Technology

Why aperture matters on your smartphone camera

Why aperture matters on your s...
Gizmag looks at smartphone lens aperture, and why it's important
Gizmag looks at smartphone lens aperture, and why it's important
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Faster lenses with a wide apertures let you isolate the subject from the background on close-up shots
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Faster lenses with a wide apertures let you isolate the subject from the background on close-up shots
The F-numbers used to detail lens aperture refer to the size of the hole, with a smaller number referring to a larger hole
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The F-numbers used to detail lens aperture refer to the size of the hole, with a smaller number referring to a larger hole
A lens with a wider aperture makes it easier to shoot in lower light situations where your subject is also moving
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A lens with a wider aperture makes it easier to shoot in lower light situations where your subject is also moving
Gizmag looks at smartphone lens aperture, and why it's important
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Gizmag looks at smartphone lens aperture, and why it's important
A faster lens with a wide aperture (in this case the F1.9 lens of the Samsung Galaxy S6) lets you isolate the subject from the background on close-up shots
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A faster lens with a wide aperture (in this case the F1.9 lens of the Samsung Galaxy S6) lets you isolate the subject from the background on close-up shots
Lenses with wider apertures mean smartphones can get good results even when the lighting is less than ideal
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Lenses with wider apertures mean smartphones can get good results even when the lighting is less than ideal
A wide lens aperture will allow your smartphone camera to perform better in low light situations
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A wide lens aperture will allow your smartphone camera to perform better in low light situations
Wide aperture lenses on smartphones let you blur out the background when shooting photos of close-up subjects
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Wide aperture lenses on smartphones let you blur out the background when shooting photos of close-up subjects
Gizmag looks at smartphone lens aperture, and why it's important
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Gizmag looks at smartphone lens aperture, and why it's important

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.

The F-numbers used to detail lens aperture refer to the size of the hole, with a smaller number referring to a larger hole
The F-numbers used to detail lens aperture refer to the size of the hole, with a smaller number referring to a larger hole

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.

Faster lenses with a wide apertures let you isolate the subject from the background on close-up shots
Faster lenses with a wide apertures let you isolate the subject from the background on close-up shots

However, that's doesn't mean lens aperture isn't important to smartphones, far from it. In fact, we'd argue that other than sensor size (and we're beginning to resign ourselves to the fact we're unlikely to see many more mega-sensored phones like the Nokia 808 and Panasonic CM1) it's potentially the most important spec, even more so than megapixels or OIS (Optical Image Stabilization).

One of the main benefits of a faster lens on a smartphone camera is improved low-light performance, an area where smartphones traditionally struggle. More light getting through the lens in these situations allows your camera to take better quality images which can be less blurry and feature reduced image noise.

Lenses with wider apertures mean smartphones can get good results even when the lighting is less than ideal
Lenses with wider apertures mean smartphones can get good results even when the lighting is less than ideal

OIS can be great when shooting static subjects in low light. But if your low light subject is moving and you want to freeze the action, you need a wider aperture so that you can also use a faster shutter speed. Because of the limitations of most smartphone sensors, you can't just pump up the ISO like you might on a dedicated camera.

As we've said, the wide angle lenses and small sensors on smartphone cameras mean you're not going to be shooting with a shallow depth of field in most situations. However, you can still achieve this when shooting close-up (a smaller distance between the camera and subject will result in a shallower depth of field) and lenses with larger apertures will let you do this more. This means your Instagram shots of your morning coffee can really pop.

Wide aperture lenses on smartphones let you blur out the background when shooting photos of close-up subjects
Wide aperture lenses on smartphones let you blur out the background when shooting photos of close-up subjects

So we now know that a large aperture is desirable in a smartphone camera, but which phones can offer the best? Well, we're beginning to see cameras with apertures in the F1.7-F1.9 range which offer much better light than F2.4 optics which were standard a couple of years ago. The aperture of recent smartphone cameras include the F1.7 of the Samsung Galaxy S7 and S7 Edge, the F1.8 of the LG G5, and the F2 of the Nexus 6P.

You might notice that we've not yet mentioned any iPhones, which are often seen as the standard of smartphone camera quality. This is because they simply don't match up to their rivals when it comes to aperture. The iPhone 6S, 6S Plus and SE all feature considerably slower F2.2 lenses, though they do use impressive processing software to deliver the performance which continues to keep many iPhoneographers happy.

A wide lens aperture will allow your smartphone camera to perform better in low light situations
A wide lens aperture will allow your smartphone camera to perform better in low light situations

In conclusion, lens aperture is certainly something you should consider on your next smartphone, especially if you value the ability to shoot good quality images in less than ideal lighting conditions. However, depending on what you want to shoot, you might also want to make sure your phone has OIS. It's this combo which helped the Samsung Galaxy S7 fare so well when we tested it shooting in low light.

6 comments
natosoco
Smartphone cameras are becoming pretty great. That said - they are nowhere near DSLR quality yet. For anything really important, I bring a DSLR. Nate http://www.savannahmitsubishi.com
Wally3178
A well written piece, but Simon has more chance of walking on the moon than convincing me to buy an Android device. Samsung make nice smartphones, such a pity they are tied to Android, they'd rule the world if they ran iOS.
christopher
@Wally - I thought the same, but had a go with Android anyhow (had to; no choice; for work). It only takes about a day before you realize it's actually better than iOS.
c w
" Samsung make nice smartphones, such a pity they are tied to Android, they'd rule the world if they ran iOS." You do understand why that doesn't happen, right? What's so much better about iOS? Android works and is more open. A widely used, community supported (as in not owned by Google) mobile Linux would be preferred (looking with foot tapping at you, Canonical), however.
MintHenryJ
Manufacturers are using wider apertures to collect more light but they're still fixed and, therefore, limited. While a phone cam doesn't have anywhere near the flexibility of a DSLR, they produce snapshots of truly amazing quality.
JasonMason
What really matters, and what cell phone reviewers almost universally fail to mention, is the equivalent aperture (usually expressed as 35mm f-stop equivalent). Unlike the actual aperture, which tells us about the light intensity and is useful for determining equal exposures across different cameras, equivalent aperture tells about the total amount of light that hits the sensor, which is the main thing that determines noise. In other words equivalent aperture takes into account both the actual f-stop and the sensor size. If you know the "crop factor" (not really a correct term when talking about cell phone cameras, but you can calculate it by dividing 35mm equivalent focal length with the actual focal length of the lens) you can use it to calculate equivalent aperture by multiplying the lens f-stop with it. This is the best and easiest way to compare low light capabilities of cameras with different sensor sizes.