Prime objective of this lecture is to present on Lenses. Long sighted people can only focus on far away objects.The eye behaves normally.When viewing nearby objects ,the lens brings the rays of light to a focus beyond the retina. Convex lenses bring rays to a focus.The more curved the lens, the quicker the rays are focused. Concave lenses make rays spread out.The more curved the lens ,the more the rays spread out. This is rectified by putting a convex lens in front of the eye.