What is auto focus? Principle of operation and common forms

What is auto focus? Principle of operation and common forms

September 13, 2023

What is auto focus? What advantages do they have that make so many users like them? In fact, most cameras on the market today are equipped with a modern auto-focus system. With the autofocus system, you will get realistic and vivid photos or movies. Let's find out with Viewfinder Media right away about this utility application through the following article.

1. What is auto focus?

Surely many people wonder what is auto focus. Auto focus is an acronym for AF, which is a self-adjusting camera to help users focus accurately when recording videos or taking pictures. The way to do autofocus is quite simple. Because this feature has a sensor function to receive and analyze light itself. The focal point will then be given the focal length the lens focuses on a defined subject.

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Learn what is auto focus?

You can also understand simply, auto focus will automatically focus on the main subject and blur other surrounding details to highlight the main subject when recording video or taking pictures. This feature makes it easier for users to take pictures. You don't need to have complicated techniques to still capture the best footage.

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2. Working principle of autofocus

What is the working principle of auto focus? The auto focus function of auto focus will be a powerful support tool for the camera. It helps the camera to identify the focus quickly and accurately. The working principle is as follows:

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Principle of auto focus

The first, the processor will autofocus (also known as AFP) creating a small distance. The AFP unit then reads the sensor and autofocuses (aka AF). It helps the user to judge whether to improve the position of the center of gravity correctly.

At this point, the information is recorded so that the AFP unit can adjust the lens to a certain distance to focus. And so on, the AFP suite automatically iterates over and over until the most effective sharp image is obtained.

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3. Advantages and disadvantages of auto focus

So what are the pros and cons of auto focus? It is an outstanding feature that any user wants. But auto focus also has advantages and disadvantages such as:

Advantage:

  • Speed up movie and photo shooting: Auto focus allows you to quickly focus when recording movies or taking photos.
  • There are many focus modes: The auto focus mode available on the camera allows the user to select the appropriate functions in filming and photography situations.
  • Ease of use and convenience: With the autofocus function, it reduces the user's manual operations when using the camera. Besides, it also makes filming and taking photos more convenient.
  • Increase the ability to record movies, take photos automatically: Auto focus will help you when filming is done correctly. From there, it brings vivid and attractive footage.
  • Good image quality: The autofocus function makes images and videos not only sharp, but also brings eye-catching photo and video quality. This helps you to capture vivid and exciting moments.
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Pros and cons of auto focus

Cons: Although considered a modern feature, always helps users save extremely attractive moments. However, auto focus also has limitations that you need to be aware of.

  • Need to do places with moderate brightness: Auto focus cannot focus if you put it in areas with strong light intensity or too bright.
  • Only available in front camera mode: Auto focus can only focus when shooting or filming with certain subjects such as people, animals, ... Therefore, it is not suitable for use. for landscape photography.
  • Easily confused with other scenes: Currently, although the auto focus mode is so popular, many people use it with many benefits. But it is also very easy to get confused with the subject and focus incorrectly.

4. Common types of autofocus

What are the forms of focus in auto focus? What are the common forms of autofocus today? Auto focus is a feature with a rather complicated way of working. To be able to own sharp photos, it is necessary to combine many factors such as: anti-shake system, sensor level, ... Depending on the purpose of use, you should choose the appropriate form of focus. . This helps bring you the most satisfactory movies or images.

4.1 Manual focus

Manual focus technique is when you manually change the position of the lens by directly rotating the lens ring or moving the person to achieve the best subject focus. This is considered a suitable technique for subjects that are difficult to focus on. With this technique, users can create extremely expensive photos.

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Manual focus

4.2 Auto focus phase detection

One of the lesser-known types of focus is phase detection. Behind each camera is manufactured integrated pixels on the sensor background. This is to serve the focusing process, making it more effective when shooting or recording movies in low-light environments.

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Phase-detection focus

On the other hand, the advantage of this phase-detection technique is its fast focusing speed. However, the downside is focusing with low accuracy. Besides, users can measure the appropriate illumination to make the photo more attractive.

4.3 Continuous focus

Continuous focus mode allows you to achieve continuous focus when the subject is moving quickly. At this time, the distance from the camera to the main subject will also change dynamically. This technique helps you focus more clearly without worrying about blurring the image. Therefore, it is very suitable for use in sports and entertainment activities.

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The photo captures many moments

4.4 Single focus

Single focus is considered one of the simplest focusing methods. Because this form only focuses once on a single object. You just need to lightly press the shutter button to immediately have extremely quality frames. No matter how you move or change position, the way of focusing remains the same.

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Single focus makes for a great picture

4.5 Contrast-comparison focus

Contrast-comparison focus is the focusing method used at two charge points on the sensor. At that time, the image will be straight up and through the sensor area during the measurement of light contrast. Although, this way of focusing is quite slow, but brings very high accuracy.

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The photo was taken with the contrast focus feature

4.6 Laser focus

Laser focusing technique is a technology that we often encounter when using modern cameras. This technique includes a laser emitter and receiver to easily detect the subject to be photographed. Thanks to that, the camera can capture focus clearly and quickly.

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Laser image focus feature

4.7 Hybrid focus

Hybrid focus is a camera technique that can assess and focus easily on its own. It is considered a combination of 2 contrast measurement mechanisms of the image. Therefore, the photographer can effectively improve the focusing speed and accuracy of the image. In particular, the DSLR series is a type of machine with a hybrid focus system with sharp image processing speed and high efficiency.

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Hybrid focus technique

4.8 Area AF

Area AF is a way of focusing an image of an area of the image that needs to be shot or captured automatically. To create a photo with beautiful area-based autofocus, there are a number of models such as:

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The photo was created from the area-mode autofocus shooting

  • Group: This is a form that allows to activate the focus point and evaluate information from one point. This means that you are looking at an object, now the group mode will follow that object even if the point of the object is lost.
  • Single-point: Nowadays, there are many DSLR cameras that perform continuous or single-point autofocus at any number of focus points in the frame. However, not all focus points can be equally focused.
  • Automic: This focus mode helps the picture to be in perfect focus. The composition of the photo will be properly resolved and adjusted. Depending on the camera, the mode will have different brightness and skin tones.

5. Influential factors when autofocusing

There are three main factors that affect autofocus performance: the movement of the camera and the subject, the intensity of the light, and the contrast of a particular subject. So how do these factors affect them? Let's answer it right here.

5.1 Subject contrast

The contrast of an image subject will be the factor that affects retrieving. A good photo will come from focusing on the background instead of being placed on the main subject. When shooting, if you see the light source moving behind the subject, you must adjust so that the main subject is out of focus. This helps create depth of field.

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Photo with subject color contrast

5.2 Light intensity

Light intensity is one of the important factors affecting the quality of a good video or photo. Adjusting the light intensity just enough will make focusing easier. But now, with the great development of technology, many cameras have been able to focus when shooting or recording in areas with very low light quality.

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The intensity of light affects the quality of the image greatly

5.3 Subject or camera movement

The movement of the subject or the camera is also a factor that affects the quality of the camera's autofocus. This means focusing will only focus on the highlight outside of the subject to be photographed. Those spots will vary in intensity, sharpness and depend on the moving light source.

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Set the right camera position

6. Compare auto focus and manual focus

Manual focus and auto focus are two types of camera lenses with different gain. While manual focus is a camera with a feature that allows you to manually rotate the knob to find the right focus position, auto focus is the opposite. Auto focus is a feature that allows the camera to automatically focus on a subject when shooting.

As for manual focus, this type of camera is often used in situations such as landscape, macro, and portrait photography. Users can manually customize the focus position to suit the subject and you want to shoot. At the same time, Manual focus is also the type of machine that can create very high-definition photos.

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Set the right camera position

With auto focus, focusing the image can become much faster and easier. Simply take a photo and the camera will automatically focus on the image. This can save you a lot of time and energy, but still get great photos.

Although manual focus and auto focus are two features with many highlights, there are still some limitations. Depending on your needs, you can choose the appropriate feature.

7. Some notes when using auto focus need to know

What are the notes when using auto focus? What should be kept in mind when using auto focus? Here are a few notes when using necessary auto focus:

  • Select the correct focus point: When using the AF autofocus mode, users should select the point to help focus accurately.
  • Choose the right focus mode: There are many focus modes, each with a different focus mode. Depending on the needs of the user, the user can choose the appropriate focus mode.
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There are a few details you should keep in mind when taking pictures with autofocus

  • Use a UV filter: A UV filter can help you reduce blue light. It helps to improve the brightness and contrast of the image.
  • Check and adjust auto focus mode settings: Users need to regularly check and reset auto focus. This is to help keep the image in focus at all times.

The above article must have partly answered you about the question of what is auto focus? From the above suggestions, Viewfinder Media hopes that you can create the most impressive photos and movies. If you have any questions, please contact us immediately for a free consultation

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Founded in 2008, we specialize in producing TV shows, ad videos, TV commercials, and other types of content. We have continuously improved our services to become one of the top production houses in Vietnam. We offer our clients the perfect service and deliver the most effective creativity.

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