For many of us, smartphones have arguably become just as much cameras as they communication devices. While some companies put more em...

A photographer's guide to buying a smartphone

By Dgsnap July 14, 2021 0 comments

For many of us, smartphones have arguably become just as much cameras as they communication devices. While some companies put more emphasis on photography features than others, there are dozens of options out there and a lot of jargon, making picking the right one a challenge.

In this guide, we’ll be explaining the key technologies of smartphone photography to help you make the right buying decision. Whether you're new to the world of photography and want to start your artistic endeavors with your smartphone or you're a full-time professional who wants the best photo-capable smartphone available as a backup to a conventional camera, we hope that you find this guide useful.

You'll find a glossary of terms at the end of the article to help you better understand the sometimes confusing jargon.

Operating System | Camera Modules | Camera Apps | Optical vs Digital | Raw Capture | Which smartphone is right for you? | Glossary

Operating system

Before you even consider hardware, the first thing you’ll want to keep in mind is which operating system you want to use. As it stands, across most of the world there are two main operating systems: iOS and Android. The former is limited to Apple mobile devices while the later—and its many variants—are used on nearly every other device from a range of manufacturers.

While there are certainly arguments to be made and nuances to point out regarding the ‘pros’ and ‘cons’ of each operating system, the general consensus is that Android (and its many variations) is used by many smartphone manufacturers and is more flexible when it comes to customization, modifications and overall control. Apple’s iOS, on the other hand, is limited to iPhone devices and is more restrictive, but generally more refined in terms of consistency across devices and apps.

Camera modules

Ten years ago, smartphones generally only had two cameras in them: one front-facing for selfies and video calls, and another on the back for more traditional photo capture. Now, most flagship smartphones have between three and four individual camera modules within their array, and even mid-tier smartphones usually offer two or three.

There are exceptions, but three camera modules usually means you’ll find a super-wide angle (equivalent to between 10mm and 20mm lens on a full-frame camera), wide-angle (between 24mm and 35mm equiv.) and standard telephoto (between 50mm and 80mm equiv.), while a fourth module might be longer telephoto (80mm equiv. and maybe even longer).

The Vivo X60 Pro+ has a four-camera array, including an ultra-wide-angle camera, a wide-angle camera, a standard telephoto camera and a 5x periscope telephoto camera.

In conventional cameras, sensor size is a major determinator of image quality, and the same is true in smartphones. Sensor sizes can vary greatly from one device to the next, and in fact, you'll often see different camera modules inside the same smartphone use different-sized sensors. Generally speaking, you can expect better image quality from larger image sensors, so if you're hoping to get the absolute most from your device, try to seek out a smartphone with a larger image sensor on at least one of the camera modules. That said, computational technology plays a large role in ultimate image quality in many smartphones, so sensor size is isn't everything.

The numbers you see inscribed next to the lenses on some smartphones sometimes reference the full-frame equivalent focal length of the lens. If a camera module has '24mm' or '50mm' imprinted next to it, you can expect the images from that module to have the same angle-of-view as a 24mm or 50mm lens, respectively, when attached to a full-frame camera system.

Generally, you can expect better image quality from larger sensors

You may also see an aperture number written next to the equivalent focal length of the lens. However, unlike the equivalent focal length number, phone makers - just like like the big name camera brands - tend to put the actual f-number rather than the full-frame equivalent. So, even if the device has 'F1.4' imprinted next to the camera, don't expect to have the same shallow depth-of-field and bokeh (background blur) as an F1.4 lens on a full-frame camera system.

To find the equivalent f-number on a full-frame camera, you must multiply the stated f-number by the crop factor of the sensor behind the lens. For example, if the device manufacturer claims an F1.4 aperture on a lens in front of a 1/2.3” (6.17mm x 4.55mm) sensor, which has a crop factor of 5.64, you must multiply 1.4 by 5.64 to get the equivalent aperture on a full-frame sensor: 7.896 (F7.9).

If all this seems confusing, that's because it is. When comparing smartphone cameras, it's probably enough just to bear in mind that a lens with a smaller aperture number (i.e., F1.4) will bring in more light than one with a larger aperture number (i.e., F2.8) and generally speaking that's a good thing. If you really want to dig into equivalent apertures, we recommend visiting MMCalc.com which is a great resource that can automatically calculate the equivalent focal length and f-numbers of a given sensor and lens combination.

Camera apps

Unlike traditional cameras, which have only one way of interacting with the sensor inside and lens attached, smartphones allow you to use different camera apps to get the most from the camera modules it has. You can expect all smartphones to have their own, proprietary camera app, but regardless of whether you’re using and Android or iOS phone, there is no shortage of third-party camera apps to fit your specific needs.

Something to keep in mind is that while some third-party apps can give better results than the camera app that comes with the phone, there are times where the built-in app offers more features and capabilities than third-party developers are able to offer. This is more of an issue with Android, where dozens of phone makers develop their own variants of the Android operating system and create too broad an array of hardware for third-party app makers to fully support. Furthermore, to our knowledge, there are no third-party apps that can offer HDR playback of HDR photos like Apple's native camera / Photos apps, so if you want the best visual, highest dynamic range experience on your iPhone, you'll want to stick to the native apps.

A home screen with just a few of the hundreds of third-party camera apps available on iOS.

As for what some of the more popular apps are, here are a few of the best third-party camera apps found in the Google Play Store (Android) and iOS App Store (iOS):

Optical vs digital (zoom and image stabilization)

Two areas where we’ve seen smartphone camera modules come more inline with their DSLR and mirrorless counterparts is in image stabilization and zoom functionality. While some manufacturers still use digital image stabilization and zoom, both of which mean you’re not getting the full-resolution of the sensor being used, more devices than ever are beginning to use optical stabilization and optical zoom in at least some of their lenses.

Digital zoom

When you see a smartphone manufacturer referring to ‘digital zoom,’ what they’re referring to is cropping in on the image and capturing only a fraction of the sensor’s data to create the final photo. When you pinch the screen to 'zoom in' you're basically just telling the camera to record images from a smaller and smaller area of the sensor.

This isn’t inherently bad, but using a smaller portion of the sensor means you'll be getting a noisier and lower resolution image. You'd get the same results if you took a picture while fully 'zoomed out' then cropped it afterwards.

There is one type of 'digital zoom' that can approach optical zoom, shifting either the sensor or the lens, or simply using the natural shifts caused by hand-shake, to capture inter-pixel detail. Google calls this 'Super Res Zoom'. Results can be impressive, and many manufacturers today offer their own versions of this technology to improve picture quality as you zoom in.

Optical zoom

Optical zoom on smartphones is a tricky topic, with smartphone manufacturer marketing to be blamed for much of the confusion. Save for a few notable exceptions, most 'optical zoom' functions you see in smartphones nowadays work by simply switching to a different camera module with a longer focal length. While it is optical, it's not really 'zoom' as most photographers would recognize it.

Markings on Vivo's X60 Pro+ show a full-frame equiv. focal length range between 14-125mm. But rather than a single lens with that 'zoom' range, Vivo swaps between its four non-zoom camera modules.

Instead, when you see a smartphone manufacturer advertising 3x, 5x or even 10x optical zoom, what they’re likely referring to is the camera array contains a camera module with a focal length that’s 5x longer than the standard camera module on the device, which itself can vary from manufacturer to manufacturer. So, when you choose 3x or 5x ‘optical zoom’ in the camera app you’re using, what’s likely happening is the smartphone is switching from using its standard camera module to its telephoto module, which may not be as 'telephoto' as you're expecting, since most standard camera modules in smartphones tend to be wide-angle.

An illustration from Huawei showing the 10x periscope 'zoom' lens found inside its P30 Pro smartphone.

One more type of zoom to be aware of is 'field-of-view fusion' zoom, present in, for example, Huawei's P30 Pro. This technology uses both a wider angle and telephoto module to synthesize an image for any field-of-view in between the wide angle and telephoto focal lengths. For example, the P30 Pro has a 3x and 5x module; a 4x shot uses the 5x module for the center portion of the 4x image, and the 3x module for peripheral portions of that 4x image. The end result is better image quality for these intermediate zoom ratios compared to simply digitally zooming the image from the wider module.

This can all get complicated pretty fast, but the nice thing is all this happens behind the scenes so you can just focus on picture-taking. So long as you understand what the specifications and capabilities are of the phone you’re planning to purchase, you should be able to make a wise purchase decision, and make the most of whatever zoom capabilities it has, be they optical, digital or hybrid.

Digital stabilization

Digital stabilization in smartphones is usually achieved by using the data from the built-in gyro sensor to track movement while taking a photo or video and applying that data to the final image to compensate for any blur or jitters from shaking. This technology has improved over the years yielding gimbal-like video footage, but in the end, every version of it requires some of the pixels, usually around the edges of the frame, to be sacrificed in order to get a more steady shot.

Certain devices get around this by recording a slightly higher resolution than is needed, knowing, for example, that recording 4.2K resolution video will result in proper 4K video once digital image stabilization is applied, but that isn’t always the case.

Optical stabilization

As is the case with conventional digital cameras, smartphone cameras can come with one of two flavors of optical image stabilization: lens-based or sensor-shift. Over the years, both technologies have been improved dramatically, to the point where newer smartphones offer stabilization performance similar to some of the best traditional camera bodies and lenses on the market.

Lens-based optical stabilization in smartphones works similarly to that in traditional optically stabilized lenses for DSLR and mirrorless cameras. Either the entire lens or a subset of elements inside the lens are mounted on a magnetic stabilization system that keeps the image steady, even when the phone itself might be moving. Due to space restrictions in smartphones, usually the entire optical assembly is stabilized (just as the entire unit, as opposed to individual elements, is moved for focus).

Below is a visualization showing the lens-based optical image stabilization found in a camera module on the Apple iPhone 7:

Sensor-shift image stabilization, on the other hand, mounts the sensor itself to a stabilization system, while the lens in front of the sensor doesn't move. This has the same general effect of lens-based optical stabilization system, but offers a few other benefits. Specifically, sensor-shift image stabilization can correct for roll/rotation—something lens-based image stabilization can't do and something that can offer significant stability with video in particular.

Sensor-shift image stabilization also has the benefit of being able to double as a means of capturing high-resolution photographs using pixel-shift technology. This method of supersampling will shift the sensor over by a predetermined amount of pixels or sub-pixels (to capture inter-pixel detail) over the course of multiple frames to capture enough data to create a supersampled photograph with a higher resolution - and lower noise - than the sensor itself is capable of capturing in a single frame.

Above is a visualization of the sensor-shift image stabilization found on Apple's iPhone 12 Pro smartphones:

Raw capture

By default, all smartphones and most conventional cameras capture either JPEG or HEIC/HEIF files, which are processed and saved in-camera ready for sharing and printing. 'Raw' image files are exactly what they sound like – they're not 'cooked'. To get the most out of a Raw file you need to process it manually, either in an app, or in a desktop application like Adobe Photoshop or Lightroom. Traditionally, the benefits of doing this are that you get a lot more control over your final image (you make the decisions about contrast and saturation etc., rather than leaving it to the camera), at the expense of a more time-consuming and complex workflow.

Some smartphones offer the option to capture photographs in Raw mode, and of those that do, nearly all use the Digital Negative (DNG) file format. Some smartphone manufacturers, such as Apple with its ProRAW format, have built upon the DNG file format with their own, but the specific advantages these DNG derivatives offer are usually limited to specific applications that have the proprietary support built-in.

Below is a gallery of images captured with the Vivo X60 Pro+ smartphone. The gallery provides the straight out of camera JPEGs captured alongside the Raw (DNG) files, which you can download on a desktop or laptop to see the difference:

If you're interested in capturing Raw images on mobile devices, be aware that the output might not end up looking as good as the straight-out-of-camera JPEG/HEIC, even with proper editing. Due to the relatively small sensor size of camera modules found in smartphones, the benefits of Raw aren’t nearly as substantial for mobile devices as they are for dedicated DSLR or mirrorless cameras.

This is because many of the straight-out-of-camera images you see from modern devices combine data from multiple frames (or even multiple camera modules) to create a near-seamless composite that results in more dynamic range, lower noise and sharper images than is possible with a single exposure – even those captured in Raw mode.

An exception to this rule is Google's Pixel line of phones, which output Raw DNGs that, like its JPEGs, are a result of its multi-shot capture mode, post alignment, stacking and averaging of many frames. Ideally, this is the type of Raw all smartphones would output; that is, all the computational smarts the JPEG/HEIC output benefit from, but without all the white balance, tone mapping, sharpening and noise reduction operations so as to allow for maximum flexibility in post-processing.

Techniques such as image-stacking, when combined with powerful AI-trained processing methods, can yield images that are similar in quality to dedicated camera systems, so it's worth doing a bit of research to make sure you get the very best of what's available, especially considering the processing power and capture modes in smartphones is changing with each new generation.

So, which smartphone is right for you?

Ultimately, it depends on what you plan on shooting the most with your smartphone. Below are just a few use-cases that should help you determine which features are most important when choosing a smartphone.

Portraiture

Whether it’s friends or family, if you’re planning on taking a lot of portraits, you’ll want to find a phone that has a solid portrait mode. Since most smartphones can’t replicate the same shallow depth of field as traditional camera systems, many manufacturers have developed dedicated ‘Portrait’ modes that can separate the subject(s) from the background and apply a blur to emulate the look of a fast lens with a large maximum aperture.

Different manufacturers have different means of doing this, so take into account whether the phone is separating the subject from the background using a hardware approach (a second camera module, Dual Pixel sensor, LiDAR or a dedicated depth sensor) or software-based approach only (known as 'segmentation', which uses machine learning to identify, mask and separate human faces and bodies from backgrounds and foregrounds).

Generally speaking, the former will provide better separation between the subject and background as well as more accurate and gradual transitions between in- and out-of-focus areas, as a reference depth map is calculated. However, these days most phones use a combination of hardware and software techniques to achieve pretty convincing results. The best ones can emulate the depth-of-field and degree of blur of a full-frame lens of the same stated F-number, even down to the character of the bokeh.

Sports photography

Any kind of sports photography with a smartphone is a bit of a challenge, if only because of the likely distance between you and the action. But, if you insist on getting the most from your device, you’re going to want to make sure it has a quality burst capture mode, which will allow you to capture dozens of frames at once and sort through each of them to find the one that best captures the moment. And as sensor sizes get larger and depth-of-field gets shallower, you'll want one that can track and focus on your subject quickly at those high capture rates as well.

Macro photography

It should go without saying that if you want a phone that can capture solid macro images, you’re going to want to find a device that has a built-in macro lens. These can be a bit challenging to find, as they’re more niche since they require a dedicated camera module, but they do exist.

Although it will affect image quality, another option is to buy an add-on macro lens, which can replicate the effect of a dedicated macro lens through additional optical elements.

Street / documentary photography

To quote Chase Jarvis, "the best camera is the one you have with you". And the best smartphone for street and documentary photography is one that's accessible and ready to quickly grab a shot.

For some, that might mean a smartphone with only one camera module and a few shooting modes to ensure as little effort is needed to compose and capture the image. For others, that might mean having a slew of camera modules with different focal lengths to ensure you can capture subjects near and far away without having to move around too much.

Whatever the case is, you’ll want to take into account your entire mobile photography workflow and ensure the operating system, device and camera modes you choose are ones that will require as little input and friction as possible so you can capture that decisive moment. It's worth noting that most phones these days have a swift, one-touch method to access the main camera for fast access.

Landscape / travel

If scenery and cityscapes are more your cup of tea, you’ll probably want to focus on a smartphone with high-resolution capture modes and one that has at least two or three camera modules with different focal lengths. Not only will having multiple focal lengths to choose from ensure you can get promising photos while far away from your subject, it will also allow you to compress your scene more for those shots when you want to tighten your composition up a bit without sacrificing resolution.

While not all smartphones come with a high-resolution photo mode built in, newer flagship devices are starting to gain this ability. This extra resolution should help if you plan to make larger prints.

Video / cinema

If you prefer videos over stills, you’ll want to find a camera that not only has quality video capture modes (4K video at 30 fps should be the minimum you’re looking for), but also has a solid image stabilization system onboard. Even more so than with stills, image stabilization in video is important for keeping your footage looking smooth and professional.

As we mentioned earlier, sensor-based image stabilization should yield better performance compared to lens-based image stabilization, due to its ability to correct for roll/tilt. However, this component is less important if you plan on using your smartphone with a mobile gimbal, which should be able to make up for any stabilization deficiencies on the smartphone itself.

Equally as importantly, you'll want to consider the performance of the phone's digital image stabilization, which has become so good in some models that it might replace the need for a gimbal altogether. However, the quality of the resultant footage can vary from model to model.

Also, while many phones have offered some form of high dynamic range video capture for some time now, some newer flagship devices are coming with high-dynamic-range output modes (HDR10, HDR10+, HLG, and even Dolby Vision). These output modes add flexibility when grading in post-production, giving you more flexibility and creative control over the final product. Perhaps more importantly, they allow you to take advantage of the high dynamic range of the latest (typically OLED) screens on these devices, which, with their very high peak brightness levels and deep blacks, can 'stretch' out your HDR capture over a wider display range so that it doesn't look flat.

Glossary

Android - A mobile operating system created by Google and used in smartphones from a variety of phone makers, many who create their own unique spin on the stock operating system to provide a unique experience.

iOS - The mobile operating system used by Apple in its iPhone devices. Unlike Android, which is free for other manufactures to use and customize, iOS is available only on Apple mobile devices.

35mm / full-frame equivalent - A way of understanding the characteristics of a lens when used on a non-full-frame camera by relating it to the 35mm film format that’s familiar to many photographers. Most commonly used in reference to focal length: e.g a 28mm lens on an APS-C camera is equivalent to a 42mm lens on a full-frame camera.

Depth of field - This describes how much of the scene in front and behind the point of focus appears acceptably sharp. An image with shallow depth of field leaves the background (and foreground) appearing blurry and out-of-focus. An image with deepdepth of field contains a greater amount (depth) of sharp detail.

Fast / slow lens - An informal way of describing a lens' aperture in terms of its relation to exposure time. 'Fast' lenses have large maximum apertures (low F-numbers), which allow the use of shorter, 'faster' shutter speeds. 'Slow' lenses have smaller maximum apertures, and typically require longer, 'slower' shutter speeds.

Focal length – Expressed in millimeters, focal length describes the angle of view of a lens. Telephoto lenses have a long focal length, and wide-angle lenses have a short focal length. The longer the focal length, the narrower the angle of view and the morezoomed-in it appears.

Wide / telephoto lens - A way of describing the field of view offered by a lens. Long lenses are more zoomed-in, while wide lenses are zoomed-out and capture a wider angle of view.

4K video / 8K video - The next generations of TV resolution beyond 1080 'Full HD.' 4K footage measures around four thousand pixels along the long edge: at least twice the resolution of Full HD. 8K is twice the resolution again but is currently used to provide creative flexibility for projects that will be viewed at 4K.

First-party app - This refers to an application developed by the manufacturer of the device it's being used on. Most times, each smartphone manufacturer will have its own camera app that has specific feature sets that may or may not be available to third-party developers.

Third-party app - These are mobile applications designed and developed by people and entities not directly related to the smartphone manufacturer. These are usually downloaded through an app store on the device (or side-loaded in the case of Android) and can vary in price.

Straight-out-of-camera - This refers to JPEG or HEIC images that have been captured and processed directly on the device. Unlike Raw files, which contain all the raw information from the sensor, straight-out-of-camera photos (often shortened to SooC) are 'what you see is what you get.'

Raw - A Raw image is a file that contains all of the raw data captured by the image sensor. Usually seen as 'DNG' files in smartphones, these tend to offer more flexibility in post-production applications that support Raw editing, which can result in more creative control after capture.


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