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Lens Focal Length & F-Stop Focal Length and F Stop are basic indicators of lens performance Focal Length affects magnification and angle of view, while F-stop affects brightness While a wide variety of lenses are available, they are broadly grouped by focal length and F-stop. Lenses with short focal lengths will have a wide angle of view, while longer focal length lenses will have stronger magnification, creating what is called a telephoto lens. The F-stop value shows how bright the lens is, i.e., how much light will pass through it when the aperture is opened to its maximum. The smaller the aperture value, the brighter the lens. A brighter lens gives a photographer more freedom in a variety of situations. What is Focal Length? Focal length is the distance from the center of the lens to the imaging point (focal plane) where the light for the image is collected. When a lens is described as a "50mm lens," it is referring to its focal length. Different foc...