What is focus? What to do? The most popular types of focus today

Focusing is one of the basic skills that any photographer should know. Let’s find out with lassho.edu.vn how the camera’s focus mechanism works, what it is used for, and how many common types of focus mechanisms are available today!

Each manufacturer owns different proprietary focusing technology, so the interface to access focus modes on each device’s device is hardly the same. The following basic information will help you have an overview of what focus is and how to use it flexibly to take unique and creative photos!

What is focus?

Focus is the ability to take pictures with the help of the lens and sensor resolution , to produce beautiful – sharp images as desired, in which the subject will be highlighted, the surrounding background area will be highlighted. will be blurred.

Working principle of focus

The autofocus sensor is the engine that helps the camera achieve precise focus and clearly show details and color arrays within the range of the image through the lens. Each sensor determines the relative position of the focus by the change in contrast at its corresponding point in the image – assuming contrast corresponds to sharpness.

The autofocus process typically follows the following operation:

• First, the autofocus processor (AFP for short) will make a small change in the focusing distance .
• The AFP then reads the autofocus sensor (AF for short) to assess how much of the focus position should be improved.
• The information will be recorded for AFP to re-adjust the lens to create a new focusing distance.
• Like that, the autofocus processor is repeated as the steps above until the image is optimally sharp .

For autofocus, the whole process takes place in a fraction of a second. However, with subjects that are difficult to focus on, the autofocus camera does not seem to satisfy. Therefore, the photographer needs to focus manually.

Factors affecting the ability to focus

There are 3 factors that affect focus: Light intensity, subject contrast, and camera or subject movement.

Note that each of these factors is not independent; in other words, the camera can automatically focus even on a dimly lit subject if the subject also has extremely high contrast, or vice versa. This has important implications for your choice of focus point

Light intensity

The light factor will decide to choose the focus point corresponding to the sharp edge to clearly show the texture – detail of the image. Sufficient light intensity will make focusing easier, but many cameras and sensors are now able to focus in low light.

Contrast of the subject

The contrast of the subject will affect the ability to focus, meaning the device will focus best on the background, not on the subject.

Observe in the image, if the light source moves behind the subject, the photographer will adjust the subject out of focus to create a depth of field.

If the camera has trouble focusing on highlights outside of the subject, the lower contrast (but still stable and reasonably lit) focus points will remain sharp and bring out the subject. .

Camera or subject movement

The movement of the camera (or subject) will be related to the ability to focus when shooting.

Focusing will focus on the outer highlights of the subject and these will vary in sharpness as it depends on where the light source moves, even the movement of the subject itself. there.

Types of popular focus today

Some popular focusing mechanisms today are as follows:

Manual focus (Manual)

With this focusing technique, you change the position of the lens or focus group by rotating the lens ring or moving the photographer to feel the best way to focus on the subject.

This technique is suitable for focusing on subjects that are difficult to focus on , or want to create a unique image according to the intention of photography.

Single focus (Single)

One Shot/Single Servo/S-AF/S/AF-S… is considered a simple form of focusing, that is, focusing only once on the subject . When you lightly press the shutter button, the camera will immediately say that the focus is on, but even if the subject later moves, the focusing distance will not change.

Continuous focus

The forms of Continuous AF/C-AF/AI Servo/AF-C, etc. are all considered continuous focusing methods. This mode allows you to continuously focus on the subject as the subject moves in the frame, the distance from the camera to the subject will dynamically change (meaning the focus will automatically adjust accordingly).

This form of focus is suitable for sports photography, constantly moving subjects such as children, animals, etc.

Hybrid focus (Hybrid)

The AI-Focus/Auto-Servo AF/AF-A function, etc. is considered a hybrid form of focusing, the camera will completely self-assess the scene and decide for the focus .

Hybrid focus is considered a combination of two contrast measurement and phase difference detection mechanisms to help photographers improve focusing speed, including accuracy. The DSLR series will focus in a very effective way of matching/out-of-phase, as if the focus system is constantly following fast-moving subjects.

However, space for the mirror chamber and separate focus unit is required, so shrinking the body size is not easy.

AF Area Modes

Area AF will come in several varieties, such as:

• Single-Point

Many DSLR cameras today perform single or continuous autofocus on any number of individual focus points within a frame.

Specifically, high-end DSLRs may have 45 or more AF points, while other cameras may have at least one central AF point.

• Group

Group area mode focus is not much different from Single-Point. This mode allows to activate several focus points and evaluate information from that cluster of points. That is, when you are aiming at an object, group mode will try to continue to follow the object even if the point on that object is lost (predicted action).

The camera in this mode can detect faces, and lock points on the subject’s eyes for easy tracking in motion.

• Dynamic

This focus mode will lock a point and continue to track the subject if it moves to surrounding points, even points outside the Group area points.

• Automatic

This is the focus mode that seems to be perfect when you want to focus on the composition, or other things around the subject.

Depending on the camera, this mode can look for skin tones and lock onto that point of the subject, which will self-assess information from multiple points to track the subject as closely as possible – that is, showing sharp details. every gesture.

Hopefully, the above useful knowledge will help you know the basic concept of focusing as well as its role in taking photos, flexibly using the focus mechanism to get the beautiful photos you want. .