One of the most popular trends regarding the smartphone market is certainly that related to cameras. Lately we have seen rumors that describe devices with eight rear sensors. But then there are smartphones that have proven to be able to take high carat photos with a single camera.
The most striking case is that of Google Pixel 3a, which scored a total of 101 points on the well-known DxOMark platform. The latter is obviously not a definitive yardstick, but it makes us understand that it is possible to create an excellent photographic sector even with just a few lenses.
Why then do manufacturers insist on putting more sensors?
No, it's not all the scene
Let's immediately dispel this myth: companies all over the world did not go crazy out of the blue when they decided to implement more photographic sensors. Indeed, the presence of more physical lenses really has advantages very important, of the aspects that many users take for granted, but which are useful in the daily context.
The main reason why secondary sensors are used is the impossibility of inserting "zoom lenses" in such thin devices. By using more lenses, therefore, it is possible to have more focal lengths. This means, in practical terms, that the zoom is performed without losing too much quality (obviously up to a certain point, since the secondary lenses often have different characteristics than the primary ones).
Maximum zoom Google Pixel 3a
Maximum Zoom Huawei P30
Above you find a comparison of the zoom achievable on the same subject by Pixel 3a (on the left, single sensor, the maximum digital zoom is 7x) and Huawei P30 (on the right, which has a telephoto lens capable of offering 3x "optical" and digital zoom up to 30x). As you can see, the difference in maximum zoom level is clear, Huawei P30 manages to go much further.
Google clearly had to stop at 7x not to notice too much the loss of detail due to the use of the single sensor. However, user preference comes into play here: the Californian company has "hidden" the hardware shortcomings well through the software and therefore someone could consider a good quality at 7x more than enough.
Another aspect to consider is the much appreciated one Portrait mode (Bokeh). For the uninitiated, through it you can take photos that highlight the subject in the foreground, blurring the rest. The secondary sensors on smartphones are often used to ensure quality blur, a creative use of the areas contained in the out of focus planes of the photo.
This "technique", obviously linked to the depth of field, benefits enormously from the presence of optics with different focal lengths. Below you can see a shot taken with the bokeh mode of Pixel 3a (on the left, the blur is done via software) and a photo taken with Realme X2 Pro (on the right, a 2MP physical sensor is used for the depth of field) .
Portrait – Google Pixel 3a
Portrait – Realme X2 Pro
As you can see, Google is doing an excellent job from this point of view and is slowly showing that it is possible to achieve quality bokeh also through machine learning. However, many manufacturers continue to prefer the "standard" approach, which can potentially lead to better results (although in reality the bokeh of some smartphones made via a physical sensor is lower than that of Google).
One Zoom – Normal photo
One Zoom – Wide angle
Do not underestimate also the wide angle lenses, to take images with a wider view. To make you better understand what type of photos you can take with this type of sensors, above you will find shots taken with Motorola One Zoom, a medium range that has a wide angle lens (117 degrees). On the left you can see how many details a smartphone can capture without a wide angle lens, while on the right you can see that the view is much wider. We already have four sensors: main, telephoto with wide focal length, wide angle and depth of field sensor. We have therefore "recomposed" the photographic sector of many smartphones on the market, but we have not finished treating all the types of lenses available.
In fact, lately the producers have decided to insert some lenses dedicated to macros. The latter are photos taken at a very close distance (above you can see shots taken with Honor 20). Usually they are carried out at a fixed focus just four centimeters from the subject. These are sensors that often return final results at not exciting resolutions and that are not exactly easy to use.
In short, there is still a long way to go from this point of view. To give you a concrete example, many lenses of this type are just 2MP and only Samsung has decided to go up to 5MP with Galaxy A51 and Galaxy A71. In any case, in the future we will probably see significant improvements and the macros could become much more interesting. As we often reiterate in our reviews, these sensors are closer to marketing needs than to real utility.
Understand that, at the moment, going beyond the sensors mentioned is therefore a bit of a gamble. In fact, so far most manufacturers have limited themselves to using solutions of this type. Just think of the recent Xiaomi Mi Note 10, which has made a lot of talk about itself because of its excellent photographic sector.
The latter includes a 108MP main sensor, a 12MP lens for bokeh mode, a 5MP sensor for 5x optical zoom, a 20MP wide angle and a 2MP lens for macros. In short, difficult to go beyond such a configuration.
Going beyond sensors, there are some techniques designed specifically to improve quality final shots. For example, Nokia 9 PureView uses its sensors to take the "same photo" and then combines the shots all together to obtain a more detailed final result and with a wider dynamic range.
Another very important technique related to the photographic sector is pixel binning, which combines data from multiple pixels into one to have a higher quality final result. For example, a 48MP main sensor can be used to take a 12MP shot, in which four pixels have been interpolated into one. There are several smartphones that use this default technique and allow you to shoot at maximum resolution only through the "Pro" mode. The advantage? High resolution shots during the day and images with less noise in night contexts.
But why is this happening? One of the main problems encountered when making a smartphone is the size of the photographic sensors. In fact, as you have probably already noticed, some manufacturers are forced to make protruding cameras because the body of the device is too small to physically contain the module. On a photographic level, the size of a sensor is very important: generalizing to the extreme, the wider the aperture is (number "f"), the greater the light that can be captured, the size of the pixels instead impacts on the final sharpness and the "digital cleaning" (which is noticed above all with gradually higher ISO, which can have more or less noise).
However, having to insert small sensors, manufacturers must use techniques such as pixel binning to avoid problems such as digital noise, since a very high resolution shot would probably not be able to capture enough light in certain contexts. The main disadvantage of this technique is that clearly the final resolution is affected, but lately the manufacturers are also managing to implement 108MP sensors and this means that, by interpolating four pixels in one, final shots are obtained at 27MP. Definitely not bad for a smartphone.
Obviously the manufacturers also develop interesting features to differentiate their smartphones from those of the competition. Let's think, for example, of the astrophotography mode of Pixel 4 XL, which allows you to photograph the starry sky very well (find examples in our review of the Google device). When evaluating the photographic performance of a smartphone, all these are very important aspects, since they actually guarantee a concrete advantage to the user.
Clearly, each person has different needs and someone could safely say they don't need one sensor or the other. What is certain is that the photographic sector of mobile devices has evolved in unthinkable ways until a few years ago and probably in the future we will see some beautiful ones. Will the path of software algorithms taken by companies like Google get the better of the physical sensor war? We'll see.
If you want to see the photos included in this article without compression, we recommend that you take a look at our Drive folder.
