Zooming

Zooming is the process of changing the apparent size of subjects within an image or scene, achieved by altering the magnification of the optical system or by resampling the image. In photography and videography, zooming is commonly realized with a zoom lens that varies its focal length, producing an optical zoom. Optical zoom changes magnification without changing image resolution, preserving perspective when the subject fills the frame. Lenses are described by their focal length range, such as wide-angle zooms, standard zooms, and telephoto zooms.

Digital or electronic zoom simulates magnification by cropping and enlarging the image data. This enlarges pixels and reduces detail, often creating softness and artifacts. Some cameras and software combine optical zoom with digital zoom (hybrid zoom) to extend reach, but image quality depends on sensor resolution and interpolation algorithms.

Other domains: In maps and image viewers, zooming changes the viewing scale instead of the subject, often via zoom levels or scale factors. In microscopy and astronomy, zoom refers to lens magnification or instrument optics. In computer graphics, zoom can be implemented by adjusting the projection or camera transform, allowing real-time magnification of scenes.

Limitations: Optical zoom requires hardware and may introduce larger, heavier lenses and potential optical compromises; digital zoom does not create new information and degrades quality. Effective zooming balances magnification with resolution, noise, and perspective to maintain image integrity.