Here is a simulation of a telescope. The light from the distant object on the left side comes into the Objective lens (the left lens) and forms a real image {image 1}. The second lens is called the EYEPIECE lens, and is positioned so that the first real image forms at the focal length of the eyepiece lens (this model shows it forming just inside the focal length so that you can see how the image forms). The first real image becomes a real object for the second lens, at the focal length, thus forms a final virtual image {image 2} essentially at infinity. [As the "parallel" rays come into the eye, from the image at infinity, they will converge to form an image on the retina, thus you resolve the image.] You can slide the eyepiece lens toward the left to illustrate adjusting the focus of the telescope. For example : if the original object is very far away, the first real image will form close to the focal length (and you would need to move the eyepiece lens closer to the other lens). If the original object is a little closer, then the first real image would form a little farther away from the focal point .. thus you would need to move the eyepiece lens away from the objective lens, so that the first real image can be at the focal point of the eyepiece lens. Refresh applet