Rear Mount Assembly

• This part of the lens connects the lens to the aperture through a series of washers and rings as well as a small number of carefully placed screws. This part of the lens is important to camera stability. Using a lens without the rear mount assembly can seriously damage the rest of the lens.
  
  

Iris

• The iris of the camera lens is named after the iris of the human eye. The iris on a camera somewhat mimics the function of the human iris, limiting the amount of light that the camera is exposed to. Opening the iris will allow more light into the image and increase the brightness while closing the iris will do the opposite. Some cameras only come with automatic irises, while others have manual ones allowing the photography to fine-tune the exposure.
  
  

Lens Elements

• Lens elements are a small group of various lenses of different shapes and sizes. These usually consist of biconvex lenses, convex lenses and plano-convex lenses. The names describe the shape of the lens and in which direction the lens curves. Biconvex lenses, for example, curve outward on both sides.
  
  

Focusing Ring

• The focusing ring is an important instrument in adjusting the lens elements. It can bring different parts of the desired photograph into focus. Many modern digital cameras include an auto-focus function that can be toggled via a physical switch. Some focusing rings will have markings estimating the distance of the object to be focused on from the tip of the lens.
  
  

Electrical Connector Strip

• The electrical connector strip is what joins the lens to a camera in digital photography. This is not how the lens is mounted, but how the camera properly communicates with the lens. It is important that the strip is properly aligned with the camera for functions such as auto-focus to work properly.