A variation in focal length can be achieved with afocal attachments that fit in front of the native lens. This is a bit like using a fixed lens camera to take photos through the eyepiece of telescope. Afocal attachments of the telescopic type are created by the separation of a pair of lens elements by a distance numerically equal to the sum of their focal lengths, giving the principal planes at infinity, i.e. the device has no focal length. Incident parallel light emerge parallel but the diameter of the beams is changed. As opposed to wide angle lens, the telephoto lens attachment decreases the field of view (FOV) of smartphone camera and presents a magnified image. This lens also differs from a macro lens attachment because of long focusing distance and use in a wide range of working distances.