There are four types of lenses used in digital cameras. These are: fixed focal length lens, retractable zoom lens, fixed zoom lens and interchangeable lens. Each lens has its own advantages and disadvantages, and it is for the photographer to decide which lens to use. This decision is made on the kind of pictures that the photographer needs to shoot, and the skill levels of the photographer.
Most low-end cameras sport fixed focal length lens. They are sleek and compact and easy to work with. Almost all functions like controlling the light intensity to focusing are done automatically in these cameras. A single push of the button is all that is required to shoot a picture.
Cameras with these lenses can be used for home photography. They can also be used for nature photography or for shooting group pictures in the macro or landscape mode. Lens converters cannot be used with these cameras because they have a fixed lens system. Optical zoom facilities are also absent. They are best for children since they do not require much understanding.
Most mid-range cameras have a retractable zoom lens. This essentially means that you would be able to zoom into a picture to a maximum level of 3X. This is not very high but works well for home photography. It is also useful for beginners. These cameras have an inbuilt shutter system that protects the lens. The zoom starts automatically functioning once the camera is witched on. Other than that the functioning of the camera is mostly automatic. However, lens converters cannot be used with these cameras too. The plus point is that the models are very sleek and elegant. They are also lightweight and compact.
If photography is your job then it is best to use a camera that has a fixed lens. The biggest advantage of using a fixed lens is that you can use lens converters with ease. They just have to be fixed on to the lens. They are not retractable in nature. By using the lens converter you can improve the quality and the style of the photographs.
An added feature of most of these cameras is the high level of magnification that can be attained. The magnification ranges from a mere 3X present in a retractable lens camera to a 12X. Along with lens converters you can also use external flash units and filters. The user is in better control of the camera functions though the controls may be confusing at times. Manual operation is also possible. The camera is definitely bulkier than automatic cameras, and more expensive.
The SLR digital cameras with the interchangeable lenses are definitely for the professionals. In these cameras the entire lens system can be detached and replaced by a new lens system. This allows the photographer to capture almost any kind of photograph. The zooming and the picture quality are also excellent. The only disadvantage is that you should be a skilled photographer; only then you can handle this camera. Each separate lens used with these cameras is costly and needs to be stored carefully.