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The main camera is one of the most important sections of any upper-middle-range smartphone today. Although manufacturers are generally usually focus on highlighting the number of megapixel cameras on their mobile, the fact is that to determine the quality of the camera of a smartphone is not enough to only know the number of megapixels. The focal length, the focal aperture or the size of the photodiodes are just some of the data that must also be taken into account when choosing a good camera on a smartphone.
But, before getting into the technical stuff, let's start by really getting to know the cameras on our smartphones. Let's take our mobile, look at the number of megapixels that its main camera has and, regardless of the number we find, can we really say that we know what megapixels are? The first thing to know is that a megapixel is one million pixels, and the pixels are each tiny squares that we see if we increase the zoom to the maximum on a photograph taken with a camera.
A high number of megapixels, summarized in a very brief way, guarantees us only two things: a good resolution of the photograph in case we want to crop it (that is, even if we cut out a part of the photograph, the image will still have a good quality) and a good resolution when developing the photographs on paper. From here, the number of megapixels has little or no influence on the quality of the snapshots.. Even a high number of megapixels in a poor-quality sensor can be counterproductive (in fact, when a manufacturer introduces an excessive number of megapixels in a sensor, the photodiodes become too close to each other, and the electrical interference that between them will be responsible for the famous noise that is often mentioned when analyzing the camera of a smartphone).
So what determines the quality of a camera on a smartphone? Although talking about these terms means entering a highly debatable field, what there is no doubt about is that the size of the photodiode is one of the determining factors when it comes to knowing in advance the quality that a camera can offer. a mobile. Photodiodes are cells that are responsible for receiving the light that the camera sensor captures to transform it into an electrical impulse that is then interpreted by the processor. The size of the photodiode determines the level of detail that a smartphone camera can capture, and in a comparison between two cameras with the same number of megapixels we can conclude that the larger the size of the photodiode,The higher the quality of the final photograph (the larger the surface area on the photodiode, the greater the amount of light that can be captured).
And although the size of the photodiode is not a data that all manufacturers provide, there is a formula that allows us to easily calculate the size of the photodiode of the sensor of any smartphone camera. We just have to know the width of the sensor and the maximum width of the resolution photographs which is able to get a smartphone; With these two data, we divide the width of the sensor by the maximum width of the photographs, and we multiply the result we obtain by 1,000. The result of this operation is expressed in microns, and corresponds to the size of the photodiodes that the sensor incorporates inside.
For example, the camera sensor of the new Samsung Galaxy S6 has a width of 3.35 millimeters and a maximum width of the resolution in the photographs of 2,988 pixels; We divide 3.35 by 2,988, multiply the result by 1,000 and the figure we get is 1.12 microns, the exact size of the photodiode with which this mobile is advertised.
And so that we understand the importance of this data even better, we are going to compare the cameras of two completely opposite smartphones: the iPhone 6 (market price: from 700 euros) and the Cubot S308 (market price: somewhat more than 100 euros). A priori, the two are presented with a main camera of eight megapixels and both are capable of taking pictures with a maximum resolution of 3,264 x 2,448 pixels. So what is it that differentiates them? The iPhone 6's camera sensor is a Sony Exmor RS that is 3.6 millimeters wide., while the camera sensor of the Cubot S308 is a DW9714 (belonging to a company called Dongwoon Anatech) that has a width of 0.8 millimeters ( at least that is what is indicated on the website of the manufacturer of this sensor, although in some sources we can read that the width is 1.2 millimeters; in any case, the conclusion is similar).
If we apply the photodiode size calculation formula, the figures speak for themselves: the iPhone 6's photodiode size is set at 1.471 microns, while the Cubot S308's photodiode size reaches a size of 0.32-0, 49 microns. And for us to understand it even better, just take a look at a comparison of two photographs taken with the cameras of these mobiles. This comparison not only shows us the obvious difference between the camera of a low-end mobile and the camera of a high-end mobile, but it also confirms the little importance that the number of megapixels can have when analyzing a camera in a smart phone.
Picture taken with the Cubot S308 on the left; photo taken with iPhone 6 on the right .
But if we think that knowing the size of the photodiode of our camera we are prepared to choose wisely a camera on a smartphone means that we are still very far from the reality of the world of photography. It is also important to note many other concepts as the focal length (the distance between the lens and the sensor, typically set between 25 and 30 millimeters in high - end mobile), the focal aperture (the smaller the this figure, the greater the amount of light that can pass through the sensor, and high-end mobiles usually have an aperture between f / 2.0 and f / 2.4) or image stabilization(It reduces the effects that can appear when the camera shakes slightly when taking a photo or video, and is especially useful if it comes in the form of optical image stabilization)
And even with all these concepts clear, it may also be the case that the needs we have regarding the camera of a smartphone make us need some of its data to be completely different from those recommended in this article. In any case, the data indicated in this text are intended for everyday use that any user would give their smartphone. Nor have we taken into account the post-processing technologies that each manufacturer can apply to the photographs taken with their mobile camera.
Summary of guidelines for choosing a good camera
- Megapixels do not indicate the quality of a camera. They serve to give us an idea of the resolution that we can expect in the photographs, but it should not be a determining factor when choosing between several smartphones.
- The size of the photodiode is determinant in the quality of the photographs. It is impossible to establish a minimum or a recommended figure for this characteristic, although we must bear in mind that, regardless of the number of megapixels, high-end mobiles incorporate sensors with a photodiode size greater than 1 micron.
- The camera sensor manufacturer is also important. When choosing a smartphone for its camera, it is essential that we know the manufacturer of the sensor that incorporates the main camera inside, and in the case of several mobiles with a sensor made by the same manufacturer, it is important that Let's know the differences that exist between each sensor model. If what we are looking for is a minimum guarantee of quality, we just have to take a look at the sensors that incorporate the high-end smartphones of the moment: the Samsung Galaxy S6, the Sony Xperia Z3, the iPhone 6 and the LG G3 incorporate a main camera with Sony sensors (IMX240 Exmor RS, IMX220 Exmor RS, Exmor RS, and IMX135 Exmor RS, respectively).
- The focal aperture of high-end mobile cameras is usually between f / 2.0 and f / 2.4. If it is lower, even better (it allows the entry of a greater amount of light).
- Optical image stabilization helps make camera results much better, but good digital stabilization doesn't have to be far behind either.
- The optical zoom offers a much better image quality compared to a conventional digital zoom, although due to size issues today there are still few mobile phones that incorporate this technology (the Samsung Galaxy S4 Zoom, for example; just look at the size of your camera to understand why other high-end mobiles come with digital zoom).
- Autofocus, HDR mode or ISO settings are some of the add-ons that we must also value when analyzing and buying the cameras of various smartphones.
Second image originally posted by gizmag . First example photograph originally published by Etkchina, second originally published by imore . Last image based on an image originally posted on deviantart .
