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Unformatted text preview: 7/31/2008 1 Key Concepts: 1. Lenses 2. Images 3. Film Observations About Cameras ¡ They record the light from a scene on a film or sensor ¡ Good cameras have to focus, cheap ones don¢t ¡ They sometimes have zoom lenses ¡ Some cameras have bigger lenses than others ¡ Cameras have ratings like focal length and f- number SHADOWS Regions not completely visible by the light sources Light Source Object Shadow PINHOLE CAMERAS Object Image Pinhole ¡ What affects focus? ¡ What affects size of image? Light from an Object ¡ An illuminated object reflects or scatters light ¡ You see object via this reflected or scattered light ¡ The object¢s light forms diffuse illumination ¡ You can¢t form an image on a screen from this diffuse illumination Lenses Use Refraction Curved lenses follow the same rules as flat interfaces, using local surface normal Lens A lens bends light twice Follows laws of refraction at each surface. Close-up 7/31/2008 2 A camera uses a? A. converging lens to form a real image. B. converging lens to form an imaginary image. C. diverging lens to form a real image. D. diverging lens to form an imaginary image. Clicker Question 1 Converging Lenses ¡ A converging lens uses refraction to bend light rays ¡ Light rays converge after passing a converging lens ¡ Rays from a common point on an object converge to a common point on far side of the converging lens Lenses Double Convex Lens Double Concave Lens Converging Lens Diverging Lens Concave Lens Convex Lens Light is Converging Light is Diverging F F¡ C f Terminology of Convex Lens F: Focus f = focal length C: Optical Center Principal axis Let¢s get focused£ ¡ Parallel rays from a specific direction are focused by a convex lens to a focal point....
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This note was uploaded on 02/07/2010 for the course PHY 1405 taught by Professor Russell during the Fall '07 term at Baylor.
- Fall '07