Power Generator
Imaging Lens
Image Sensor
Polyoptic Wheel
Viewfinder, Eye
LED Flash
LCD Display
Electronics
Image Processing

Downloadable PDFs

Teach
With
Bigshot
Prev
Introduction      Pinhole      Refraction      Lens Basics      Thin Lens
Lens Properties      Focusing      Image Appearance      Illustrations
Next

Focusing

Lens law
Figure 12: Thin lens law

Let us revisit the example of you taking a picture of your friend with a thin convex lens. If your friend (object) is standing at a distance o from the lens, and the focal length of the lens is f, then the distance i at which her image is formed can be found using the thin lens law [1]:

Lens Law Equation

The above equation tells us that, for an object at distance o, there can be only one distance i at which the image is focused. If the image sensor is not located at this distance i, your friend will appear blurred in the image. For this reason, most cameras allow you to adjust the distance between the sensor and the lens so that your object of interest can be brought into focus. This process is called focusing.

Prev
Next

ReferenceReferences

[1] E. Hecht, Optics. Addison Wesley, 2001.