zoom lens
Quick Summary
A zoom lens, also known as a variable-focus lens, is a type of lens used in cameras and projectors that allows the image size to be changed continuously while maintaining focus. This is achieved by moving lens elements or groups within the system, enabling one lens to replace multiple interchangeable lenses.12
Originally developed for motion-picture photography to create zooming effects, zoom lenses are now common in still cameras. They are complex, often containing 12 to 20 elements to ensure sharpness across a range of focal lengths. Zoom lenses for still cameras can offer focal-length ratios of 2:1 to 4:1 or more.2
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motion-picture technologyPrincipal parts…need for a variety of focal lengths (ranging from ultrawide angle to telephoto) to photograph scenes under the best conditions. To make changing focal lengths more convenient, the lenses have sometimes been mounted on a turret, so that one out of a set of three lenses may be quickly selected.…
Read More…need for a variety of focal lengths (ranging from ultrawide angle to telephoto) to photograph scenes under the best conditions. To make changing focal lengths more convenient, the lenses have sometimes been mounted on a turret, so that one out of a set of three lenses may be quickly selected.…
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technology of photographyVariable-focus lensesIn variable-focus lenses the focal length can be varied by movement of some of the elements or groups within the lens system. One lens can thus replace a range of interchangeable lenses.
Read MoreIn variable-focus lenses the focal length can be varied by movement of some of the elements or groups within the lens system. One lens can thus replace a range of interchangeable lenses.
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microscopeMechanical components…as a portion of a zoom lens, which permits continuous variation of the magnification over a limited range without loss of focus. Such microscopes are widely used in industry.
Read More…as a portion of a zoom lens, which permits continuous variation of the magnification over a limited range without loss of focus. Such microscopes are widely used in industry.
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electron microscopeOperating principles…varied, the electron microscope has variable-focus lenses, and the distance between specimen and objective lens and the separation of the lenses remain constant. The magnification is determined mainly by the value of the current (for magnetic lenses) through the intermediate and projector lens coils. The image is focused by changing…
Read More…varied, the electron microscope has variable-focus lenses, and the distance between specimen and objective lens and the separation of the lenses remain constant. The magnification is determined mainly by the value of the current (for magnetic lenses) through the intermediate and projector lens coils. The image is focused by changing…
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