Building a Keplerian Telescope requires two converging lenses, an objective and an eyepiece, aligned coaxially and sharing a focal point. Parallel ways enter the objective, converge at the shared focal point, invert and are made parallel again by the eyepiece. The magnification and increased intensity are represented by the tighter spacing of the rays as they enter the eye. We find the focal point of the eyepiece by focusing the image of the hallway on a sheet of paper. While objects infinitely far away would focus to a point, objects that are only much further away than the focal length focus to an image that is barely past the focal point. We then focus the objective lens the same way on the same sheet of paper. Once both lenses share a focal point, they form a working telescope. As you can see, they form a focused, inverted image of the hallway. A Galilean telescope uses a similar converging objective lens, but a diverging eyepiece. Again, these two lenses share a focus, but now the eyepiece is inside the objective's length. Starting with the existing capillary in telescope, the converging eyepiece is replaced with a diverging lens. The objective is then brought closer until the telescope comes into focus. This Galilean telescope is not only much shorter in length than the capillary, it also produces a non-inverted image.