To define a camera lens you just have to consider photography without it and you may understand its essence. How should a human being define life without the eyes? With the only downside that we couldn’t hook an image printer and a memory card to save the images that we see so photography has been an indispensable tool for most of us. The rest of course is mimicry as we only imitate nature in technology. As of this writing we have a long telephoto lens for eagle’s eyes, a macro lens for a hummingbird’s and of course the very popular fisheye lens for those images that defy orientation. So if you are fascinated with life beyond what your eyes could normally see, picking up a digital SLR camera with the lens of choice is the common way to go and sure enough seeing the beauty of life which used to depend on the eye of the beholder has just gone farther beyond as the beholder gets equipt with 'sets of eyes' aside from what was 'standard issue'.