From black-and-white lenses to free-form lenses, from 3x optical telephoto to 10x periscope optical telephoto, to super-sensitive arrays from RGGB to RYYB sensors, and from AI imaging to computational optics, Huawei previous generations of Mate series mobile phones have largely become the vane for the development of mobile imaging technology.
With the release of the Mate 50 series mobile phones, mobile imaging has ushered in a new design - a ten-stop variable aperture lens, which controls the amount of light entering by adjusting the opening and closing of six aperture blades.
Here comes the question, what role does aperture play in imaging, and is variable aperture technology worth our expectations?
Popular science knowledge: What exactly is aperture?
A long time ago, people needed to understand the three elements of exposure (aperture, shutter and ISO) before learning photography, and mastered the Sixteen Sunshine Rules. They needed to determine the aperture, shutter and film with appropriate sensitivity based on the light and shadow of the current shooting scene. After confirming that they were correct, press the camera shutter.
Many photography enthusiasts need to learn the exposure triangle
The definition of aperture
After entering the era of smartphones, moving images have become simpler and smarter. We only need to open the camera APP, turn on scene recognition, aim at the shooting scene, press the electronic shutter , and all the rest of the work is left to the AI imaging algorithm.
, when paired with a self-developed ISP or NPU chip, can turn the phone into a "night vision device" and eliminate relatively bright photos in extremely dark environments.
Therefore, when we choose a mobile phone today, we often focus on the size of the sensor, how high the pixel value is, whether it supports optical image stabilization , etc.
As one of the three elements of exposure, aperture is often regarded as a parameter that does not require too much attention.
In fact, aperture and shutter speed are the two core parameters that control the visual properties of the camera, which can open up more creative effects.
The so-called aperture is actually a "visible but intangible" mechanical component inside the lens. It is composed of multiple sets of blades, and in the middle of the blades is an adjustable hole.
Yes, the aperture is defined as the opening in the center of the set of blades in the lens, which affects how much light can pass through this small hole and enter the CMOS sensor at the bottom of the camera per unit time.
By adjusting the size of the aperture, you can control the amount of exposure .
The role of aperture
F value is a parameter used to describe the "size" of the aperture. Its calculation formula is the relative value obtained by "focal length ÷ lens aperture diameter", such as F/1.4, F/2.8, F/4, etc.
It should be noted that the larger the number immediately following F/, the smaller the aperture, which means the less light passes through.
This picture comes from digital blogger @Giant Photography
The smaller the number behind F, the larger the aperture, and the more light that passes through , which is the large aperture we often talk about.
At night or when the ambient light is insufficient, only a larger aperture can ensure sufficient light intake, thereby capturing more dark details, improving the brightness of the picture, reducing noise, and the shutter speed is faster under the same exposure time.
The most significant visual impact that the aperture can produce is the change in the depth of field: the larger the aperture, the smaller (shallow) the depth of field range, and the more obvious the background blur effect, which can make the subject more prominent and suitable for close-ups; the smaller the aperture, the larger the depth of field range (deep), the sharper the background, and all elements in the scene will be clear, suitable for shooting landscapes.
This picture comes from digital blogger @小wolfah小狼
In other words, the bigger the aperture, the better.
When taking pictures with your mobile phone, you need to match the appropriate aperture according to the scene you are shooting. If you blindly pursue a large aperture, you will lose more than you gain.This is like a kitten's pupils, which narrow into a slit when there is sufficient light during the day, and become rounder and larger at night.
does not have the best aperture, only the most suitable aperture.
Analog Era: How to achieve background blur
Professional SLR (or mirrorless) cameras can be equipped with various lenses, many of which can manually adjust the aperture.
In the field of mobile phones, the size of lens modules is generally only a few tenths of that of SLR lenses , which makes it difficult to accommodate complex mechanical structures.
In order to be suitable for more shooting scenes, the customary method for mobile phones is to use a variety of lenses with different focal lengths and apertures. If necessary, they can also be combined to image .
Generally speaking, the main camera and portrait lens of new smartphones are most popular with large apertures, while the apertures of ultra-wide-angle and telephoto lenses are generally very small.
So, are mobile phones with small apertures destined to miss out on background blur?
Take photos first and then focus.
The answer is naturally no.
As early as 2013, mobile phones represented by Nokia Lumia 1020 (41 million pixels, 1/1.5-inch sensor, F/2.2 aperture) can realize the function of "take pictures first, focus later" (Lumia 920, Lumia 925, Lumia 928, Lumia 1020 and Lumia 1520 and other models will also be supported in the future).
In 2014, Android phones represented by Honor 6 Plus also introduced similar functions. You can take photos in the "large aperture" mode in the camera APP. When previewing the photo, you can reselect the focus and adjust the aperture size between F0.95~F16 to change the depth of field.
Today, large aperture mode has almost become a standard feature of smartphones.
It should be noted that the function of taking a photo first and then focusing is not achieved by changing the physical aperture of the camera lens .
The earliest Lumia and subsequent Android phones adopted two very different ideas.
The solution chosen by the Lumia mobile phone is to move the lens from beginning to end when taking a photo, and record the image of each focus point, which is equivalent to taking a picture of all the points that can be in focus the moment we press the shutter. When selecting the focus later, the image corresponding to the focus plane will be derived directly based on the focal length of the scene we selected, and it can be done with just one lens.
The implementation idea of Android mobile phones is to use dual-camera blur.
After turning on the large aperture mode, the main camera is responsible for recording the panorama, and the secondary camera is used to record depth of field information and determine the subject and background. The two are combined and saved as an ordinary photo. When focusing again later, the system will determine whether it is the subject or the background based on the focus point we selected, then take out the subject and perform Gaussian blur processing on the background.
Lumia’s solution requires a lot of calculations, and the background blur is shallow. When shooting portraits, the blurring effect at the equivalent 24mm end is very average. The dual-camera blur on Android phones has high requirements on imaging algorithms. The blur caused by Gaussian blur may be unnatural. In some scenes, there may be cutout errors and "accidents" such as overturning of object edge processing.
Take pictures at any time and adjust at any time
As the AI computing power of smartphone processors continues to improve, and related imaging algorithms continue to mature, most new mobile phones can directly adjust the aperture size in the camera APP, and adjust the depth of field effect at will during shooting preview. Press the shutter to directly generate satisfactory works, and take pictures at any time and adjust at any time, without even the involvement of a second lens.
Similar functions: Some brands have integrated them in professional mode, while others have placed them in portrait mode. Many new products can even record videos of people with blurred depth of field using a single front camera. With the support of algorithms, everything is possible.
However, the aperture adjusted in the camera APP is not the physical aperture of the lens. To be precise, it should be regarded as an electronic aperture. It relies on multi-frame synthesis to achieve the shooting effect of small aperture and long exposure.
You can try it. In the same viewing range, use the electronic aperture of your mobile phone to take a photo at F/1.6 and F/16 respectively. You will find that the exposure of the two photos is the same, and the difference is just the degree of background blur.
Moreover, the blur effect is not as natural as that produced by a SLR lens with a large aperture. Whether or not it is defective depends entirely on the quality of the lens itself and the AI imaging algorithm.
As the saying goes, needs to be hardened. If you want your phone to perfectly adapt to bright and dim scenes and take photos with the best depth of field, you still need the phone lens to be in the most appropriate aperture range .
If mobile phone lenses could also have an adjustable aperture function similar to that of SLR lenses, wouldn’t everything be perfect?
Looking back at the past: the development history of variable aperture
Huawei believes that a mature mobile phone imaging system includes multi-dimensional software and hardware, and needs to build four major technical bases: "light (optical design), machine (mechanical structure), electricity (photoelectric conversion), and calculation (image algorithm)". The first ten-stop variable aperture lens of Huawei Mate50 series is an upgrade of the optical design.
However, variable aperture is not Huawei’s first launch. Variable aperture has already appeared in the mobile phone field as early as 13 years ago.
Nokia debuted with variable aperture
In the history of mobile phones, the first product to introduce a variable aperture design was the N86 launched by Nokia in 2009. It was not only equipped with a mechanical shutter (up to 1/1000s), but also provided three automatically adjusted apertures of F2.4, F3.2, and F4.8, which could not be switched manually. The reason why
N86 has a variable aperture design is to neutralize the mechanical shutter of up to 1/1000s and avoid overexposure under strong light.
Android mobile phone relay race
Following the Nokia N86, the second appearance of the variable aperture in the mobile phone field was 8 years later.
At the end of 2017, Samsung released the Heart of the World W2018, as well as the Galaxy S9/S9+ series of mobile phones released in early 2019. The main cameras have two-speed variable apertures, F/1.5 and F/2.4. Through clever design, the physical aperture can be switched freely.
In automatic mode, the F/2.4 aperture will be enabled when the light is sufficient to capture clear and sharp images, prevent light blooming under large apertures, and restore the true color of the image. In low-light scenes, the aperture will automatically expand to F/1.5, and the brightness of the viewing area will be significantly improved. In macro or professional mode, you can manually switch to F/1.5 aperture, which can bring a more realistic and delicate depth of field effect than the blur achieved by software.
Pay attention to the change in the aperture size of the main camera above.
It is also 2019. OPPO’s R17 Pro also features a “smart aperture” function that can switch between F1.5 and F2.4. When the ambient light is dim, the main camera of the R17 Pro can automatically enlarge the aperture to F/1.5. In daytime or brightly lit environments, the lens aperture will shrink to F/2.4 to avoid the problems of edge image quality and highlight overflow that may occur with a large aperture.
Unfortunately, OPPO’s smart aperture was “end of the world” after experiencing the R17 Pro, and Samsung’s variable aperture also “retired” after the Galaxy S10 series.
The latest mobile phone with a variable aperture design is the Xperia Pro-I launched by Sony in 2021. It features a 1-inch Exmor RS sensor and two adjustable apertures of F2 and F4. The F2.0 aperture can achieve "ultra-shallow depth of field", and the background presents a beautiful and natural blur. When shooting with F4.0, the distant and close views are clearer and the image is sharper.
Looking to the future: A brief analysis of Huawei's super light-changing main camera
Compared with the existing variable aperture design, What is the difference between the "super-light changing main camera" featured in Huawei Mate 50 series mobile phones?
A more complex mechanical structure
Whether it is Nokia, Samsung, OPPO or Sony, the variable aperture used in mobile phones mentioned above can only switch between two (or three) fixed gears, and does not achieve free changes within a range of aperture values.
Huawei's Mate50 series features the "super optical variable main camera", and implements the first ten-stop variable aperture lens design, which can bring an experience similar to the adjustable lens aperture on a traditional camera.
Judging from the Huawei patents that were exposed online earlier and the promotional materials of the Mate 50 series mobile phones, the so-called "super optical variable main camera" is composed of a 50-megapixel RYYB super-sensitive sensor, a high-precision annular magnetic field micro-control motor, and a multi-speed adjustable blade lens group composed of 6 sets of aperture blades. By adjusting the opening and closing of the six aperture blades, the amount of light entering can be controlled.
The effect of multi-speed variable aperture
There are two operating logics for the super light-changing main camera of Huawei Mate 50 series mobile phones. The first is to enter the professional mode, where you can fully adjust the ten-stop variable aperture from F1.4 to F4.0, which is convenient for photography enthusiasts to find the golden aperture point that best matches the current light environment and personal taste through manual adjustment;
The second is in the default automatic mode, the camera APP provides four stops of aperture, which can intelligently match the aperture size according to different scenes. At night and under low-light conditions, use a large aperture to increase the amount of light entering the lens, resulting in a bright shooting effect; when taking group photos during the day, use a small aperture to ensure that the characters in front and behind are clear and the edges of the picture are rich in details; in high-power zoom scenes, use a large aperture to further improve the image quality and capture clear and sharp images.
With the help of 10-stop adjustable aperture, Huawei Mate50 series mobile phones can bring more accurate portrait segmentation calculation capabilities, and also bring progressive and layered optical-level blur to portrait shooting. The protagonist of the portrait is three-dimensionally highlighted, creating a blockbuster atmosphere.
At the same time, the variable aperture can also bring professional optical-level blurring capabilities, which can accurately focus on small objects such as necklaces and pearls, bringing a sub-millimeter precision shooting experience. It can also adjust the depth of field range and blurring degree at will, allowing for greater creative space.
A rational view of the significance of variable aperture
Before Huawei, whether it was Samsung, OPPO or Sony, they all regarded variable aperture as a "passenger" on the road of mobile phone research and development. They had owned it and promoted it, but in the end they chose to break up.
The reason is that on the one hand, the variable aperture will increase the complexity and size of the lens's mechanical structure, which will lead to high costs and potential life-span risks.
The multi-main camera fusion computational photography technology advocated by Honor Magic series mobile phones
On the other hand, with the support of large-size sensors, multi-pixel fusion technology, multi-frame synthesis of handheld super night scenes, HDR and computational photography concepts, the use of AI is enough to simulate a realistic depth of field effect.
In addition, when shooting portraits, macro or distant scenery, it can be handled by a more professional auxiliary camera (such as a periscope telephoto lens). The main camera only needs to have a large aperture on the outsole.
Therefore, the variable aperture ultimately lost to cost and AI computational photography. This time in , the variable aperture has been "picked up" by Huawei again, and optimization and innovation have been carried out. From the past either A or B, it has been changed to a ten-stop adjustable aperture that is comparable to professional SLR camera lenses. This process of continuously adjusting the aperture has made many photography enthusiasts hooked.
However, this is only for photography enthusiasts.For ordinary users, they may not use the professional mode to take photos throughout the entire life cycle of the mobile phone. In daily use, they can also find the gain effect of the four-stop smart aperture in the automatic mode on the final image.
In fact, the super light-changing main camera is a necessary innovation for Huawei Mate series mobile phones to escape the trap of involution and continue to maintain its professional image positioning.
After the marriage of Leica and Xiaomi , Huawei was forced to launch its own imaging brand XMAGE. In addition to continuing the computational optics, primary color engine and super periscope telephoto lens featured by the family's predecessors, it needed to find another selling point that could highlight the professionalism of imaging. The multi-level adjustable aperture that can only be achieved with professional SLR cameras is undoubtedly a good breakthrough.
is just as Huawei advertises - variable aperture, hard-core control.
allows users to freely control changes in aperture. This is an area that other mobile phone manufacturers will not venture into in the short term, and this is enough to attract the attention of photography enthusiasts.
As for ordinary consumers, variable aperture can only be used as a bonus item when purchasing a mobile phone, and is not a mandatory option.
