01 Core Concept: Focus Point vs Metering Point Many beginners think these two are the same, but they each have independent functions: 1. Focus Point Function: Controls sharpness. It tells the camera: “Make the plane where this point lies (the focal plane) sharp.” Working Principle: The camera drives the lens motor to adjust the lens elements, making the subject at the selected focus point form the

sharpest image on the image sensor. Visual Indicator: The small square (green or red) shown in the viewfinder or screen. 2. Metering Point Function: Controls brightness (exposure). It tells the camera: “Use the brightness of this area as the reference to determine the overall

brightness of the entire photo.” Working Principle: The camera measures the brightness of the area at the metering point, calculates what it considers an "optimal" combination

of shutter speed, aperture and ISO, and adjusts the frame to what the camera deems "proper brightness". Visual Indicator: Usually invisible (unless spot metering links with the focus point is enabled); or displayed in the center area under partial

metering modes. One-sentence Summary: The focus point decides where to be sharp; the metering point decides how bright the image is. 02 Use Them Separately or Together? Under the camera’s default shooting mode, half-pressing the shutter button triggers an automatic process that binds autofocus and auto

metering into one single operation, designed to deliver a fast, intuitive aim-and-shoot experience. Naturally, operation characteristics vary with different autofocus modes. In Single AF, half-pressing the shutter locks both focus and exposure. In Servo AF， half-pressing the shutter enables continuous focusing and metering. Details are as follows:

Core Essence By default, the physical action of half-pressing the shutter button simultaneously samples and locks the focal plane and exposure value at the

same moment. This is based on a subject-first assumption: the camera takes the subject aligned with your selected AF point as both the object needing sharp

focus and the most important reference for correct exposure. Though this default linkage is efficient, it does not suit all shooting scenarios. Professional workflows often require controlling focus and

exposure as two independent creative tools. For this reason, most professional camera systems offer high customizability, allowing

photographers to separate these two linked processes. This is where AEL/AFL and AF-ON come into play. 03 Advanced Essential Tools: AEL & AFL To realize independent control of focus and metering, cameras are equipped with two lock functions: 1. AEL (Auto Exposure Lock) What it is Locks the current exposure parameters (shutter / aperture / ISO). No matter how you move the lens, the overall image brightness remains

unchanged. Why you need it The camera’s metering system works mechanically, always trying to render the scene as 18% neutral gray. When you recompose the

frame, changes in bright and dark areas will cause the exposure (photo brightness) to shift. How to use it Aim at the area with your desired brightness (e.g., the sky or a gray card), half-press the shutter or press the AEL button to lock exposure, then

recompose and shoot. Applicable Scenarios Panorama Stitching: Exposure must be locked when shooting multiple frames for a panorama. Otherwise, inconsistent brightness across shots

will leave obvious stitching seams. Silhouette Photography: Meter against the bright sky, hold AEL, then recompose to frame the subject. The sky will be properly exposed while

the subject turns into a full silhouette. Backlit Portrait: Get close to meter on the subject’s face, lock AEL, then step back and recompose to keep facial brightness perfect. Complex Lighting: Set exposure first, then adjust composition freely. 2. AFL (Auto Focus Lock) What it is Locks the current focusing distance. Why you need it Normally, half-pressing the shutter triggers both focus and metering at the same time. Yet in many compositions, your ideal focus point is not

at the center of the frame. How to use it Common method: Half-press and hold the shutter (in Single AF mode). Half-shutter press on most cameras comes with default focus lock. Professional alternative: Use the dedicated AFL button (or AF-ON button) on the camera rear. This fully separates focusing from shutter release. Applicable Scenarios Focus first, recompose later: The most classic usage. Use the fast central focus point to lock onto the subject, hold AFL to fix focus, then

smoothly reframe and fully press the shutter to shoot. (Note: Watch out for cosine error). Intermittent moving subjects: Lock focus when the subject pauses briefly, then wait for the perfect shooting moment. Shoot through foreground elements: Such as photographing a distant bird through wire mesh or gaps in leaves. Without focus lock, the

camera will keep hunting back and forth between the foreground and the subject. On many cameras, exposure lock and focus lock share one combined button labeled AEL/AFL. Users can customize its function via custom

settings: set it to exposure lock only, focus lock only, or lock exposure and focus simultaneously. You may configure it according to your own

shooting habits.

Core Essence By default, the physical action of half-pressing the shutter button simultaneously samples and locks the focal plane and exposure value at the

same moment.

This is based on a subject-first assumption: the camera takes the subject aligned with your selected AF point as both the object needing sharp

focus and the most important reference for correct exposure. Though this default linkage is efficient, it does not suit all shooting scenarios. Professional workflows often require controlling focus and

exposure as two independent creative tools. For this reason, most professional camera systems offer high customizability, allowing

photographers to separate these two linked processes. This is where AEL/AFL and AF-ON come into play. 03 Advanced Essential Tools: AEL & AFL To realize independent control of focus and metering, cameras are equipped with two lock functions: 1. AEL (Auto Exposure Lock) What it is Locks the current exposure parameters (shutter / aperture / ISO). No matter how you move the lens, the overall image brightness remains

unchanged. Why you need it The camera’s metering system works mechanically, always trying to render the scene as 18% neutral gray. When you recompose the

frame, changes in bright and dark areas will cause the exposure (photo brightness) to shift. How to use it Aim at the area with your desired brightness (e.g., the sky or a gray card), half-press the shutter or press the AEL button to lock exposure, then

recompose and shoot. Applicable Scenarios Panorama Stitching: Exposure must be locked when shooting multiple frames for a panorama. Otherwise, inconsistent brightness across shots

will leave obvious stitching seams. Silhouette Photography: Meter against the bright sky, hold AEL, then recompose to frame the subject. The sky will be properly exposed while

the subject turns into a full silhouette. Backlit Portrait: Get close to meter on the subject’s face, lock AEL, then step back and recompose to keep facial brightness perfect. Complex Lighting: Set exposure first, then adjust composition freely. 2. AFL (Auto Focus Lock) What it is Locks the current focusing distance. Why you need it Normally, half-pressing the shutter triggers both focus and metering at the same time. Yet in many compositions, your ideal focus point is not

at the center of the frame. How to use it Common method: Half-press and hold the shutter (in Single AF mode). Half-shutter press on most cameras comes with default focus lock. Professional alternative: Use the dedicated AFL button (or AF-ON button) on the camera rear. This fully separates focusing from shutter release. Applicable Scenarios Focus first, recompose later: The most classic usage. Use the fast central focus point to lock onto the subject, hold AFL to fix focus, then

smoothly reframe and fully press the shutter to shoot. (Note: Watch out for cosine error). Intermittent moving subjects: Lock focus when the subject pauses briefly, then wait for the perfect shooting moment. Shoot through foreground elements: Such as photographing a distant bird through wire mesh or gaps in leaves. Without focus lock, the camera

will keep hunting back and forth between the foreground and the subject. On many cameras, exposure lock and focus lock share one combined button labeled AEL/AFL. Users can customize its function via custom

settings: set it to exposure lock only, focus lock only, or lock exposure and focus simultaneously. You may configure it according to your own

shooting habits.

However, it must be mentioned that some compact camera bodies are only equipped with a single customizable button. Users need to assign functions to these controls according to their own shooting needs. It is recommended to carefully read the automatic

operation section of your camera manual, and perform repeated testing and adjustment in actual shooting. This way, you can make the most

of your camera and operate it with maximum comfort and proficiency.