The Basics of the Lens

A DSLR camera lens is not very different from a refracting telescope or even a microscope.We need the lens to gather light and focus it while transmitting the light to the image sensor.

Here is an example of a simple lens:
It gathers light to a focus. Sort of. There are some inherent problems with a simple lens.Lets first talk about Chromatic aberration.


Because the lens is thicker in the middle than at the edges all colors of light do not focus in the same place.

There are 2 other undesirable properties of a simple lens: