About Zoom Lenses

• Zoom lenses are made up of a collection of different lens groups that move together to create a different range of perspectives. They are used to focus in on an object or item you wish to photograph. With a zoom lens, you may be standing many feet away, and depending on the power of the lens, zoom into something very closely and photograph it clearly.
  
  

Identifying Zoom Lenses

• Zoom lenses are identified by the range of zoom they have. For example, a 35mm to 200mm zoom lens has a greater range than one with a 70mm to 130mm zoom lens. There are two types of zoom lenses: optical and digital. Optical lenses move in and out to focus on the subject. Optical lenses are discussed in further detail in the next section. Digital zoom lenses merely increase the size of the image. This process can create a more pixelated image. Some cameras will advertise a combination zoom ratio. For example, part of the camera's zoom ability may be attributed to an optical zoom, but the rest of the camera's zooming ability is based on the digital zoom.
  
  

How Zoom Lenses Work

• Inside a zoom lens there are four kinds of optical groups. These four groups work together to allow you to zoom. The first group, the focus group, allows you to focus your subject. This group will sometimes focus automatically or may need to be adjusted manually. The next group, the variator group, is the group that adjusts how much a subject is magnified. A third group, the compensator group, works with the variator group by moving together to maintain the focus as the focal length and magnification changes. Lastly, the master group, the group of lenses closest to the camera itself, works to control all of the groups together and correct any visual abnormalities.
  
  

How Zoom Lenses Are Used

• Two ways camera zoom lenses are controlled are through a button on the camera itself that zooms in and out or with a turning ring on the lens itself. When prompted, the lens groups all work together to create a clean, zoomed in image. After light is transferred through all four of the lens groups, the camera body receives the light, and the image is created.