The lens of a camera is truly the eye to the world in photography. It is the viewer through which the camera sees the shot you want to take. The lens is an essential element needed to take good photographs. So when you purchase a new camera, you should always check out the type and quality of the lens. Even a camera with a superior sensor and an adequate number of megapixels will not produce good photographs if the lens is of inferior quality.

Lenses can be made of glass or plastic or a combination of both. You will want to stick with glass lenses, if at all possible, since glass offers much better clarity. In fact, the lens is sometimes referred to quite simply as the “glass”.

Small point-and-shoot, and mid-range cameras will come with a lens that is built into the camera. A digital SLR (Single Lens Reflux) camera will give you the ability to change the lenses and to use different lenses for different occasions. SLR cameras are sometimes available as a “body only” with no lens. Sometimes they come as a kit with one or two lenses to get you started. You can then purchase additional lenses as the need arises.

The lenses for SLR cameras often cost more than the camera body itself. Truth be told, however, the lens, if handled correctly, will last longer than the camera itself. So most photographers look at the cost of lenses as an investment.

Be aware that when you buy a digital SRL, you are basically buying into the line of lenses that will fit that particular camera. For instance, if you purchase a Canon camera body, you will need to use Canon lenses. The same is true of Nikon. Olympus uses lenses from Zuiko.

One of the main differences is in the lens mount. This is the point of connection between the lens and the camera. Every manufacturer has its own type of lens mount. Some lenses manufacturers like Zeiss have different lines of lenses that will fit Nikon, Canon, and Samsung SLR cameras. They do this by creating each lens with the type of lens mount used by the different manufacturer. In some cases, digital camera lenses also have to coordinate with the size of the sensor. So a four-thirds camera may use different lenses than a full-frame digital camera.

Lenses are created specifically for digital cameras. Those produced for 35 mm film cameras may mount on the bodies of a digital camera. However in most cases, the 35 mm lens is slightly larger and allows unwanted light into the camera body, causing an often unacceptable halo effect. Because most SLR sensors are smaller than the 35 mm format, there is usually also a cropping of the image when compared to the images from the film camera. These problems, in general are so severe that you will want to purchase lenses that were created specifically for a digital camera.

There are several types of common lenses: wide angle, normal telephoto, prime, and zoom. In this tutorial we will cover some of the more important aspects of a lens, including the types of lenses, the lens focal length, and aperture.