"Focus" and "Zoom" are two completely different but often confused concepts in photography and machine vision. Simply put: Zoom = changing how large the view is (angle of view / magnification) Focus = changing how sharp the view is(the position of clear imaging) Below is a detailed comparison from four aspects: principle, function, operation method, and application scenario. I. Core Definitions Terms: 1. Focus: Adjusting sharpness. Function: To form a clear image of an object at a specific distance on the sensor. 2. Zoom: Adjusting the angle of view. Function: To change the size of the imaging range, i.e., to "zoom in" or "zoom out" the frame. II. Comparison of Working Principles 1. Focus Principle: Move the internal lens group to adjust the distance from the lens to the imaging sensor (image distance), so that light from a certain object distance converges precisely on the sensor. Result: Only objects at a certain distance plane are sharp, while foreground and background appear blurry (depth of field effect). Analogy: Like squinting or wearing glasses — making objects at a certain distance clear. 2. Zoom Principle: Move multiple lens groups inside the lens to change the focal length, thereby altering the field of view (FOV). Result: Telephoto (e.g., 200mm): Narrow field of view, enlarged subject ("telephoto effect") Wide-angle (e.g., 24mm): Wide field of view, capturing more of the scene Analogy: Like walking closer to or farther away from an object — changing the area you see. Key Differences Zoom is not the same as simple magnification! Digital zoom only crops the image and reduces quality; optical zoom is real zoom. Failed focus → the entire image is blurry; changed zoom → the composition range changes.

III. Operation Methods (Taking Cameras as an Example) 1. Manual Lenses 1) Focus: Rotate the Focus Ring 2) Zoom: Rotate the Zoom Ring 2. Automatic Cameras 1) Focus: Half-press the shutter buttonfor Auto Focus (AF) 2) Zoom: Push/pull the zoom lever or rotate the zoom ring 3. Industrial Cameras 1) Focus: Focus adjustment via software-controlled stepping motors 2) Zoom: Fixed focal length lenses (most have no zoom function) or motorized zoom lenses In Industrial Vision: Most applications use Fixed Focal Length Lenses, which only support focus adjustment without zooming. When zooming is required, motorized zoom lenses (e.g., Computar MPT series) are used, with Zoom and Focus controlled via software.

IV. Practical Examples Scenario: Shooting a bird 10 meters away First zoom: Use a 200mm telephoto lens to "bring the bird closer" and fill the frame (changing composition); Then focus: Adjust focus to make the bird’s eyes sharp and clear (ensuring sharpness); ❌ If you zoom but don’t focus → the bird is large but blurry; ❌ If you focus but don’t zoom → the bird is small but clear. Industrial Camera Selection Advice: If the inspection distance is fixed → choose a fixed focal length lens + fine focus adjustment; If the inspection distance varies greatly → consider a **liquid lens** or a motorized focus & zoom lens. ✅ One-Sentence Summary: Zoom determines what you frame (composition), while focus determines whether it’s sharp (clarity). It’s like a telescope: zooming changes the eyepiece magnification, and focusing turns the knob to make stars clear. Mastering this difference will make you more professional and efficient, whether taking photos with a phone, operating industrial cameras, or selecting lenses.