Lenses
There are three different types of lenses: wide-angle, normal, and telephoto.
The normal lens is 50 mm. If you want to take a picture of a quarter using a normal lens, the quarter would appear in the correct size. Normal lens is what you and I see when looking at objects.
The wide-angle lens is anything below 50 mm. If you take picture of a quarter using a wide-angle lens, the quarter would appear much smaller than its correct size. Wide-angle lenses allow more subjects or scenery into the picture. The smallest wide-angle lens is the fish eye 6mm, lens. This lens can take a 180 degree picture.
The telephoto lens is anything above 50mm. If you take a picture of a quarter using a telephoto lens, the quarter would appear much larger than its correct size. Telephoto/macro lenses allow less of the subject into the picture. These lenses are great for close-ups.
The pictures below were all taken from the same spot, but each used a different lens.
