Camera f-number. What is "aperture"? I do not want to understand the characteristics! Which smartphone to buy with good cameras

When choosing a smartphone with a good camera, you need to pay attention to its many parameters. With resolution, everything is simple: the more megapixels, the better the theoretical maximum detail of the image. With the dimensions of the matrix and individual pixels, everything is also simple: the larger they are, the more light it captures, and the higher the clarity will be with a lack of lighting. But aperture or aperture is a characteristic that is more difficult to understand. For example, the fact that a smaller number is often better puzzles many.

Aperture (aperture) is a hole in the camera lens through which light enters the matrix. In the description of smartphones, these words are used as synonyms, but they have slightly different origins. The term "aperture" originally referred to the physical part of the lens, the aperture shutter, which controls the size of the aperture. And "aperture" is a characteristic that indicates the characteristics of this shutter.

SLR lens with variable aperture

Since this detail is absent in mobile cameras, both terms are used in the second meaning. Also, the word "aperture" is often used as a synonym for the terms "aperture" and "diaphragm". In the description of smartphone cameras, all these concepts characterize the ability of optics to transmit light.

What is the aperture (aperture) of a smartphone camera measured in

The value of the aperture (aperture) of a smartphone camera is a relative value expressed in terms of the focal length.

Focal length is the distance between the sensor and the optical center of the lens, that is, the point at which the light rays converge when they enter the camera module through the lenses. The aperture value allows you to determine how effectively the camera captures light, in comparison with others.

Smartphone camera aperture location

The numerical value of the aperture is a derivative value that indicates the ratio of the FFR (physical focal length) and the diameter of the hole in the lens. It is written in the f/X fraction format, where f is the FFR and X is the divisor. The popular f/2 aperture means that the aperture diameter of the camera is half the focal length. If the FFR is 4 mm (this is also one of the popular values, since you won’t be able to get more from a module about 6 mm high), then with an aperture of f / 2, the diameter of the lens eye will be 2 mm. If the focal length is 5.6 mm, and the aperture is f / 2.8 (the Nokia N73 camera phone had such parameters 12 years ago), then 5.6 / 2.8 = 2, that is, the “pupil” again has a diameter of 2 millimeter.

different aperture values. Hole diameters are kept to the same scale.

What is the aperture value

Since the f-number indicates the diameter of the lens opening, the amount of light entering the matrix depends on its value. The larger the hole, the more light there will be. It is precisely because the number after the fraction is a divisor, the smaller it is, the larger the physical diameter of the “pupil” will be. After all, if you divide 4 by 1.8 (f / 1.8), then we get 2.22 mm, and dividing 4 by 2.2 (f / 2.2) will already give 1.82 mm.

If you remember the formula for the area of ​​a circle πr 2 (and r is half the diameter) and make a calculation, you can determine the difference in light transmission. For a hole with a diameter of 2.22 mm, the area will be 3.48 mm2, and for 1.82 mm - 2.85 mm2. Dividing the first by the second, we get a difference of 1.22 times, that is, optics with an aperture of f / 1.8 transmit 22% more light than with f / 2.2.

Due to the fact that different cameras have different FFRs (a few millimeters for a smartphone, and 10-100 times more for a DSLR), it is impossible to compare very different cameras in terms of aperture. For example, a smartphone with a 1/3" sensor at an aperture value of f/2 captures the same amount of light as a full-frame DSLR with an aperture of f/13-f/15. However, if the camera sensors of the compared smartphones are close in parameters or identical (as in the same and , on the example of which the calculations above were carried out), then the difference in aperture ratio allows us to estimate the difference in light transmission.

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Everyone loves to take pictures with their cell phone, but the built-in camera is different in everyone, so it's important to understand what each specification means. Then you choose a smartphone with a camera that suits your needs.

In this article, we will delve into the meanings of many features so that you can judge the capabilities of the camera by reading a description or an overview of the specifications.

Diaphragm

The aperture of a lens is the opening through which light passes to the sensor and is indicated by the numerical value F (for example, f/2.0 or F/2.8). The smaller the f-number, the larger the aperture and the more light passes through the lens, and the better the camera's performance when shooting in low light conditions. The f-number you see on datasheets is the maximum possible aperture for a given focal length (more on focal length below).

For example, if a camera shoots at F/5.6, then it captures less light than at F/2.0. The 29mm f/2.2 lens on the iPhone 6 can be described as "fast", which means you can shoot at more high speed shutter. The higher the aperture of the lens (the smaller the f-number), the better it is suited for shooting low-light scenes. Therefore, choose a camera that has the smallest aperture value (F / 2.2 is better than F / 2.8).

In zoom cameras like the Galaxy K Zoom and Galaxy S4 Zoom smartphones, most often you get two pairs of numbers with a focal length. At the same time, sometimes they indicate a constant aperture, but this is more typical for ordinary digital cameras, and not for smartphones.

camera in samsung galaxy The K Zoom is equipped with a 24-240mm f/3.1-6.4 lens. This is called variable aperture. The first aperture value (F/3.1) means the maximum aperture when shooting at the widest angle (24mm), and the second F value (F/6.4) indicates the maximum aperture opening when shooting at the tele-end (240mm). When zooming, changing the focal length, the aperture also changes.

It is also important to note that in cameras with a large sensor, the aperture value affects the depth of field. So at a large aperture, you can get a shallow depth of field, thus making a beautiful blurred background, the so-called "bokeh". Unfortunately, with a small sensor, which is found in most mobile devices, such an effect is almost impossible to obtain.

Aperture F/2.8.

As the f-stop increases to F/11, the aperture decreases and the depth of field increases, as in the example below.

Focal length

The focal length is the distance from the optical center of the lens to the image plane, in telephone cameras it means to the image sensor.

When zooming, the optical center of the zoom lens changes, so the focal length value also changes. FR also tells us about the angle of view, which is especially important. For simplicity, look at the equivalent focal length of the lens, which takes into account the size of the sensor and gives you a 35mm equivalent focal length. This figure can be compared among different cameras.

The equivalent focal length tells you how wide the lens is. You can use this converter to understand what angle of view we are talking about at a certain FR in 35mm equivalent. The shorter the focal length, the wider the field of view.
For example:

iPhone 6 / iPhone 6 Plus: 29mm (35mm equivalent)
Galaxy S5: 31 mm ( in 35 mm equivalent)

We can say that with the iPhone 6 and iPhone 6 Plus, the field of view is wider, as 29mm translates to 73.4 degrees, and 31mm translates to 69.8 degrees.

At a shorter focal length, the camera can cover a wider area of ​​the scene (vertically and horizontally). This is very convenient for shooting group shots, interiors, architecture, selfies, etc. That's why smartphone manufacturers endow the front camera lens with a shorter focal length - to make it more suitable for self-portraits.

Lenses with a fixed focal length are called "fixes". This means that there is no zoom in the camera.

Galaxy Zoom smartphones have a variable focal length. For example, the Galaxy S4 Zoom is equipped with a 24-240mm f/3.1-6.4 lens. So 24mm is the focal length at the wide end, and 240mm is the focal length at the tele-end. Of course, the aperture, as we mentioned above, is maximally open at wide-angle and minimally at the tele-end.

By the way, optical zoom is calculated by dividing the maximum focal length by the shortest one. For example, in the case of the S4 Zoom, we divide 240 by 24 and get 10. In other words, the S4 Zoom has a 10x optical zoom.

Sensor size

Sensor size plays a key role in camera performance. It is generally accepted that the larger the sensor, the higher the image quality. It almost always is. For a large sensor, manufacturers can apply more technological advances that are impossible or expensive to implement in small sensors. However, among the extremely important specifications of the sensor is the size of the pixels.

Pixels are measured in micrometers (μm) or microns (μ). Some smartphone manufacturers are providing this figure as more people realize the impact of pixel size on image quality and low light performance.

The larger the pixel size (photodiode, pixel aperture), the higher its ability to collect light.

You can find two cameras that have the same size sensors but different resolutions. Here you need to decide whether you are choosing a low resolution with large pixels (like the HTC One UltraPixel) or a higher resolution with smaller pixels. Different cameras will have different sensor sizes and resolutions.

You may find a camera with large pixels that is inferior in low-light performance to another camera, due to the importance of sensor technology and image processing.

For example, sensors with BSI (Back Side Illuminated) technology use a unique design that greatly improves light sensitivity. In the BSI sensor, the wiring responsible for data transmission is located behind the light sensitive area, which allows manufacturers to create small sensors with a large number of pixels. On FSI (Front illuminated) sensors, the wiring is in the front, taking up space that could accommodate large photodiodes.

The new generation sensors demonstrate their superiority over the earlier ones, and the sensor technology continues to improve. The HTC One UltraPixel smartphone with 2.0 micron pixels does not always result in better performance in low light compared to sensors whose pixels are smaller. The iPhone 6 Plus, with its 8MP sensor and 1.5µm pixels, is currently in first place on DxOMark. TheHTC One M8 is in 18th place, well behind even the camera in the Samsung Galaxy S5 (3rd), which has a 16-megapixel sensor with 1.12 micron pixels.

The size of the sensor, in conjunction with the characteristics of the lens, affects the depth of field. With the same aperture, a larger sensor will allow you to achieve a shallower depth of field, i.e. more pronounced bokeh. The out-of-focus background effect helps to separate the subject from the background elements.

To get a blurrier background, you need a smartphone with a large sensor and large aperture.

The size of the sensor is indicated in the specification list, it can be 1/2.3", 1/2.5", 2/3", etc. This means that this is its diagonal, but it is not easy for everyone to compare sensor sizes in this way. You can contact to the online sensor size comparison tool cameraimagesensor.com or open the Wikipedia article which lists the most popular sensor types with their equivalent width and height in millimeters.

You can see that the Nokia Lumia 1020 has a relatively very large sensor (2/3 inch = 8.80x6.60mm); Nokia Lumia 720 (1/3.6 inch = 4.00×3.00 mm).

The next time you're looking to buy a smartphone, when looking through camera specs, don't forget to look at pixel size and sensor dimensions. Most modern camera phones are equipped with BSI sensors. Some have more advanced technology than others.

Image stabilization

Image stabilization is one of critical aspects many modern phone cameras. There is digital image stabilization and optical. With an optical stabilization system, the camera compensates for hand movement and shaking by shifting the lens elements in the opposite direction of movement, resulting in sharper images.

Images from Apple's patent application, which describes a method for integrating optical stabilization in miniature cameras.

When shooting handheld, small movements are inevitable, which can lead to a blurry picture. If you place your phone on a stable surface, this worry will disappear. Nose mobile phone most of the time you shoot handheld. In order to get a sharp image, follow the shutter speed rule of thumb, which states that the shutter speed denominator must be at least a number indicating the focal length in 35 mm equivalent. That is, to get a sharp image when shooting with a 30mm lens (equiv.), you need to set the shutter speed to 1/30 sec.

Many of you use your smartphone as the main camera. This is not strange, because digital SLR cameras are not cheap, and not very mobile, unlike conventional phones. If you are not professionally engaged in shooting photos and videos, you do not need such a camera at all. And for everyday Instagram photos, the phone will do.

The good news is that cameras in flagship smartphones today are not much inferior in quality to DSLRs, and the trend for dual cameras generally makes it possible to take photos in portrait mode indistinguishable from those taken on a digital camera. Moreover, cameras evolve and get better every year, even in budget smartphones.

Aperture- this is one of the characteristics of the camera in your smartphone, which you may have heard about and saw this parameter in the characteristics of the phone. Usually, it is referred to as f / 2.0, f / 1.8, f / 1.7 and f / 1.6. It is believed that the smaller the second digit in the designation, the better the camera takes pictures, but is it really so? In this article on Galagram, we talk about the aperture in modern smartphones.

What affects the quality of a photo

You may have heard the popular phrase, "The more light a camera gets, the better the photo." And this, to some extent, is true. For example, in digital cameras - the better the sensor and lens, the better you get the final picture (or video). In smartphones, the same principle applies, but there are some differences.

Since the image sensor and lens on your phone take up very little space (unlike a DSLR), the camera receives less light than a regular camera. Some manufacturers are trying to correct this situation by installing a sensor with larger pixels with sizes of 1.15-1.25 microns, which should capture more light.

Wide aperture does not always mean the best image quality

But the sensor is only half the equation for perfect photography. On the second pan of the scales are optics and lenses through which light enters the image sensor. This is where such a concept as aperture comes into play.

What is aperture in a smartphone

And so, what is aperture or aperture in a smartphone? Aperture refers to the size of the hole through which light can enter the camera. This setting is referred to as "f/2.0" (numbers may vary) and is measured by the ratio of the focal length divided by the hole size.

Thus, the smaller f, the larger the hole size and the more light gets through the optics to the image sensor. As you yourself know, a photo taken in good light even with a budget smartphone is bright, saturated, clear and has no noise.

Another good thing about a wide aperture is faster shutter speeds and a sharper and more stable photo, with no stutters or blurry areas. When a camera receives a lot of light, it "thinks" less before taking a picture. Some manufacturers are adding Optical Image Stabilization (OIS) technology to the cameras of today's smartphones, which makes it possible to achieve even better images in medium and low light.

Which aperture is better: f/2.2, f/2.0 or f/1.6

The image sensor in a smartphone is very close to an optical lens system, which is much closer than that of a SLR camera. This leads to the fact that the focal length in the phone is much shorter than that of professional cameras.

Since we know that the ideal photography equation uses focal length divided by aperture size, this helps explain why smartphone cameras have a wider aperture than traditional DSLRs. Despite a wider fixed aperture, your phone's camera isn't always better suited to capturing the maximum amount of light.

The aperture in a smartphone is different from the aperture in a digital camera

Thus, the larger the aperture in the phone, the better. Ideally, the camera should have both a wide aperture and a sensor with large pixels of 1.25-1.55 µm. But here's another problem - in the phone, the aperture has a fixed size and does not change, unlike DLSR cameras, when you twist the lens.

How is the bokeh depth of field effect obtained?

A wider aperture in a digital camera allows you to better emphasize the effect of depth of field (bokeh or background blur). But your smartphone has a fixed aperture and a small sensor that sits close to the optics. Therefore, adding the bokeh effect on the phone is much more difficult, especially when the background is close to the main subject in focus.

By comparison, a smartphone camera with an f/2.2 aperture achieves the same depth of field as a camera with an f/13 or f/14 aperture. In practice, very little blurring is obtained. Modern phones that can take pictures with a blurry background usually use special software algorithms for this, and not the actual operation of the optics.

Optics and lens quality

Another important feature of a smartphone camera is the lens. Yes, we used to call lenses large interchangeable lenses for cameras, but your phone has it too. Let the lens in a smartphone be much smaller than traditional ones, but it also consists of optical lenses. If the lens is dirty or the lenses have poor transparency, the sensor will receive less light in the end.

Lens quality becomes especially important on smartphones with wide apertures like f/1.6. After all, at a wider aperture, it becomes more difficult to focus all the light on the image sensor. This is where the so-called abrasive distortion.

Wide aperture phones are, by definition, less focused on a particular part of the scene than devices with smaller apertures and are therefore more prone to both focus and distortion issues.

Abrasive distortion manifests itself in a variety of effects. These include: spherical aberration (reduced transparency and sharpness), photo blur, field curvature (loss of focus at the edges), distortion (image convexity or concavity), and chromatic aberration (out-of-focus colors and white distortion).

Lenses in smartphones are built from several corrective lens groups that are designed to precisely focus light and reduce these aberrations. Cheaper lenses have fewer lenses and are therefore more prone to problems. Optical materials also play an important role.

The quality of lenses is difficult to judge by their specifications, and many phone manufacturers don't mention it at all. Fortunately, some well-known optical companies are now actively integrating into smartphone cameras, in particular, we are aware of such cases: Leica and Huawei, Carl Zeiss and Nokia HMD Global. LG has also implemented new lens"Crystal Clear Lens" with 6 lenses into the flagship V30 to handle the camera's wider aperture.

Conclusions: what to look for

We hope that after reading this article you have understood what aperture is. To summarize all of the above, a wide aperture does not always mean the best quality pictures. The final image is also affected by the size of the matrix, the amount of light that hits the image sensor, software and, of course, the camera optics in your smartphone. The key to a good camera is simple, these are the following parameters:

• wide aperture
• large pixels and matrix size
• well-coordinated work of software and hardware
• high-quality optical system

Therefore, when you choose a smartphone for yourself, it is better to test its camera manually before buying it to make sure that its real image quality. You should not get hung up only on the f/1.8 and f/1.6 numbers, because a high-quality camera not only has a wide aperture, but all other systems work well as a set.

A few years ago, the camera on the phone was perceived as an unimaginable miracle of technology. Photos taken at 1.3 megapixels seemed cool. Today, we can say with confidence that smartphones have replaced the “digital soap dishes”. It will be about how to choose a smartphone for the money, and not lose in the abilities of the camera.

What many pay attention to in the first place. Of course megapixels! The problem, however, is that a large number of megapixels does not guarantee high-quality shooting results. Often the quality of shooting depends on deliberately hidden details - aperture, sensor size, optical stabilization, autofocus and other parameters. Let's try to clear all this jungle.

Captain obvious - choose a top smartphone

If you can afford a premium smartphone from - Samsung, Apple, Sony, Lg, etc., then the task is as easy as possible. Take any, as a rule, flagships are always equipped with the most advanced developments. The chance of you getting it wrong is very low.

The number of megapixels and the size of the matrix

The most common misconception is that the quality of photos directly depends on this parameter. A high number of megapixels speaks primarily of better image scalability without loss of quality.
Much more important is the size of the matrix (sensor) - and not the number of pixels in it. With the same sensor manufacturing technologies, The larger the size, the better the quality of the photos. A large pixel is capable of capturing more light, which is demonstrated by technology where, at a relatively small resolution, clear photographs are obtained.
The specification indicates the diagonal in inches: 1 / 2.5 ″, 2/3. Next time, be sure to take a look at the size of the matrix and pixel.
Image from high resolution requires pretty good processing performance, and take up a lot of memory. It is necessary to take this into account, for example, the Xperia Z5 Compact has a very powerful Snapdragon 810 processor and 21 megapixels in the camera, but it is not uncommon when scrolling through the gallery that it catches the brakes in drawing the image.

Diaphragm

Lens aperture is the diameter of the hole that allows light to pass through to the camera sensor. It is denoted by the value f, and the smaller the value, the larger the diameter and the more light the lens transmits.
Aperture is a good indicator of the quality of shooting in low light. With an aperture of f/1.9, the quality in dark shooting will be better than f/2.2 . For example, f / 2.0 is a good indicator, you do not need to practically care about lighting (within reason, of course, the Iphone 5 has f / 2.2).

Focal length

Most often, this parameter is not indicated by sellers, but if you rummage through the Internet, it will not be difficult to find. It does not directly affect the quality of shooting, it affects the field of view more. For example, the front cameras have a short focal length to cover the entire face at close range 🙂 We get that a short focal length is good for shooting interiors, group photos, selfies, architecture.
It's short focal length.

Stabilization

If you see the IOS marking, which means optical stabilization, this is very good. Because, manufacturers often just talk about stabilization, without specifying how it works. There is also digital (software) stabilization, which is significantly inferior in quality. It is logical after all, it is better to shoot a high-quality picture than to try to correct a bad one with programs.
Optical stabilization compensates for trembling, involuntary hand movements, and so on, which lead to image blur.
When photographing, there is a nuance: to get a clear frame, you need to ensure the shutter speed is not less than the focal length. For 30 millimeters, the shutter speed should be 1/30 of a second.

In low light conditions, the shutter speed automatically slows down (shutter speed slows down) so that the sensor can capture as much light as possible. In such conditions, trembling has a great influence on clarity, and stabilization is indispensable.
Optical stabilization is better for photos, but it should include software that gives very good results when shooting video. But you should not think about it, digital is in any self-respecting smartphone.

Laser autofocus

Some brands, mainly LG and Asus, equip their devices with laser autofocus. The laser gives a quick reorientation from one focusing object to another. Great benefits when shooting macro objects and in the speed of focus capture.

Backlight

Manufacturers have been experimenting with xenon flash, but LED lighting is now ubiquitous. First of all, due to the increase in power with small dimensions. Smartphones are also equipped with two LEDs. The presence of two LEDs with different light temperatures of the LEDs eliminates the effect of red eyes and unnatural skin color.

Results

Let's conclude what needs to be taken into account in order to evaluate which camera is better at the same prices.

• The size of the matrix, and therefore the pixel
• Having enough processing power to process a given resolution, otherwise you will be more cursing than taking photos
• The presence of optical stabilization
• Two LED backlight
• The smaller the aperture, the better for “dark” shooting. f / 2.0 - excellent for smartphones

How to find out the camera's light sensitivity on a smartphone, and what value should you choose in order to enjoy high-quality photos later?

One of the most important points in a smartphone is its camera. Now almost every user has pages in various in social networks, where he periodically uploads photos of himself, travel, food, shopping, pets, etc. Some people even make money by posting pictures on Instagram and other networks. Modern smartphones can replace digital cameras, which sometimes greatly facilitates luggage on trips. But how to choose a device with a good camera?

Thanks to the development of technology, the number of pixels no longer plays such a decisive role as before. If you want to get a high-quality camera, then when choosing a smartphone, you should pay attention to the presence of optical image stabilization, sensor size and pixels. Another important characteristic is the aperture.

What is aperture?

Aperture measures the ability of a camera to capture light. An important detail in the device of the camera is the aperture diaphragm - the hole through which the light rays pass to the sensor. The principle of operation is similar to the structure of our eye, where the pupil and iris control the amount of light reaching the retina. A larger aperture opening allows more light to be collected, which is necessary for high-quality images.

The letter f is used for designation, where the f-factor is equal to the focal length divided by the aperture diameter (f / 1.7, f / 2.2, etc.).

Does more mean better?

Actually it is not. The smaller the number after f, the larger the aperture and the larger the aperture of the lens. This means that the camera is photosensitive and can capture more light. Thus, even in poor lighting conditions, you can take a high-quality and clear photo with a minimum amount of noise.

Perhaps the most attractive option here is last year's flagships Samsung Galaxy S7 and Galaxy S7 Edge with a maximum aperture of f / 1.7. Also noteworthy are the HTC 10, LG V20, LG G5 and LG G6 with f/1.8. Well, the most common mobile devices with an aperture of f/2.0 or f/2.2.

variable aperture

This is usually a fixed value, but sometimes a variable aperture may be specified. This is typical for devices with a camera that allows the user to apply optical zoom, change the depth of field, or change the shutter speed.

For example, a recently launched dual camera smartphone has a wide aperture mode with a range of f/0.95-f/16. In this mode, you can change the focus on already taken photos and create a blurred background effect, as in SLR cameras. With a larger aperture value, the camera will focus on the nearest object, with a smaller one, the background will be sharper.

Another example would be the ASUS ZenFone Zoom. Although the device is equipped with a single camera, it provides support for optical zoom. The aperture can be changed from f/2.7 to f/4.8, where the first value corresponds to the normal state of the camera, and the second value corresponds to the maximum zoom.

Conclusion

Aperture is one of the most important characteristics of a mobile camera. It is she who is responsible for the ability of the smartphone to take high-quality pictures even in low light conditions. However, it is important to remember that a light-sensitive camera with a large aperture will have a lower f-value.