**Features of Aspherical Lens************************************
	•In this type of lens the glass is formed into a compound curve as shown in Diagram 1 ,This results in all the light being focused at the same plane therefore eliminating barrelling distortion. The other aspect of spherical distortion is a reduction of the effective diameter of the lens.This has the effect of reducing the maximum aperture or increasing the f number, the aspherical lens can produce a larger effective diameter thereby providing a larger aperture and making the lens more sensitive to low light.Diagram 2 illustrates this feature.This technology is making possible lenses with exceptionally small f numbers,thereby reducing even further the light levels under which cameras can operate.
	< Diagram 1 > Reduction Of Spherical Aberration In Aspherical Lens
	< Diagram 2 > Decrease in f Number With aspherical Lens