Canon 10 x 30 IS Technology Guide - Page 5

Prism Binoculars/Galileo Binoculars/ Porro Prisms/Roof Prisms Q2 Why Are the Images Magnified? Basically binoculars are made up of the objective lenses for long focal points, and the eyepiece lens, for short focal points. The light from each to the two objective lenses which forms the image of an object (Fig 4-a), passes through the barrel and hits the eyepiece lens, which enlarges the image (Fig 4-b). Objective lens Eyepiece lens a b (Fig. 4) Create a telescope using two camera lenses Attach a wide-angle lens to a telephoto lens. Without shifting the optical axis, look through from the back of the lens and adjust the distance between the two lenses. You will eventually see a sharp inverted image. This is the basic structure of a telescope. Put two of these side by side and you have a pair of binoculars. In addition, the longer the focal point of the telephoto lens and the shorter the focal point of the wide-angle lens, the more the image will be magnified. It is also possible to achieve focus by adjusting the distance between the two lenses. It's very simple. Tested with the EF 300 mm f/4L and EF 24 mm f/2.8, the outcome was pretty obvious. 5