supported properly and becomes deformed causing light to come into focus at different focal lengths. The image therefore becomes distorted.
             Unwanted Refraction: pouring molten glass into a mold makes lenses. Air bubbles form in the lens as the liquid gas cools. The air bubbles cause, distorted images due to extra refractions.
             Opaque: when some wavelengths of light can't pass through the lens, visible light is dimmed when it passes through, and the lens absorbs ultraviolet radiation.
             The reflecting telescope was helpful in solving some of these problems because they use mirrors with top coated surfaces which light does not enter. Mirrors don't sag because they can easily be supported unlike heavy lenses. Since light doesn't enter the mirror, the problems of different wavelengths, chromatic aberration and opaque do not occur. However, spherical aberration can still occur because when light enters a telescope with a spherical mirror at different distances from the mirror's center, the light comes i
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