zoomlenzen

Zoomlenzen are photographic lenses with a variable focal length, allowing photographers to change framing without moving closer or farther from a subject. Internally, a zoom lens sequences several groups of lens elements that slide axially relative to each other as the user turns the zoom ring, adjusting magnification.

The zoom range is described by the zoom ratio, typically 3x, 4x, 5x, or higher (for example 24-70mm is ~2.9x, 70-200mm is ~2.9x). Common configurations include wide-angle zooms (roughly 16-35mm), standard zooms (24-70mm), and telephoto zooms (70-200mm, 100-400mm). Many standard and consumer zooms have a variable maximum aperture (for example f/3.5-5.6), becoming darker at longer focal lengths; professional zooms often maintain a constant maximum aperture (for example f/2.8) but are larger and more expensive.

Optical design emphasizes controlling aberrations across the range. Dispersive elements, aspherical surfaces, and special low-dispersion glass reduce chromatic and geometric errors; coatings suppress flare and ghosting. Modern zooms frequently include image stabilization (or vibration reduction) to counteract camera shake and improve handholding at longer focal lengths.

Autofocus is typically provided by built-in motors, with varying performance. Some cinema and high-end still lenses are parfocal, preserving focus when zooming; many general-purpose zooms are not.

Zoomlenzen are widely used across photography and video for versatility, including travel, events, sports, and documentary work. They embody trade-offs between range, speed, weight, and optical quality, and continue to evolve with advances in optical materials and coating technologies.