Having one lens for the entire range of 28 mm (wide angle) to 105 mm (2x telephoto) means not having to change lenses for both ends of the range. If you do not change lenses, then you save valuable time when taking pictures, and since the camera is does not have to be opened, as when changing lenses, then you do not have to worry about getting dirt and dust in it.
The only advantages of having two lenses for the 28-105 mm range would be if they were of better optical quality than the single lens, or had lower f-stop ratings, meaning they were "faster", that is, allowing more light into the camera.
First answer by Tigr. Last edit by Tigr. Contributor trust: 1024 [recommend contributor]. Question popularity: 5 [recommend question]
