The Thin Lens Equation
|f||focal length of lens||m|
Tips to Remember
- The object distance do and the image distance di are both measured from the lens. In your standard case with a convex lens, the lens will be between the object and the image, and both do and di will be considered positive.
- Be careful with the algebra in the fractions. If do and di are both 8 cm, that doesn’t make the focal length 16 cm. See the example at the right for the correct algebra.