1 point for correct analysis (show your work), 1 point for correct magnification and correct focal length. 1. Watch the video for the procedure. Use both images to determine the focal length. 2. Use one image to study the magnification of the lens. Compare the magnification found using the object height h and the image height h' (m = h/h) with the magnification m = -i/0. Remember that magnification is negative if the image is inverted. We now focus the smaller image on the screen and replace the screen with a pencil and stand at the end of the bench so that we look over the screen into the lens. You should see the image lined up with the pencil. Swinging your head sideways-the image should remain stationary