Lens and imaging equation
The light rays emanating from the object must be collected through a lens to form the points of an image. The imaging equation describes the applicable laws.
• Ray from the object parallel to the optical axis (parallel ray)
• Ray from the object through the focal point of the lens (focal ray)
• Ray from the object through the central point of the lens (central point ray).
The central point ray passes through the lens without changing direction. The parallel ray passes through the focal point on the other side of the lens, and the focal ray becomes the parallel ray.
Note: The imaging equation is also frequently known as the “lens equation."
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What are lenses needed for?