Adjust the values and see how the telescope telescopes. Press space to actually do the telescoping. The green lines are the rays of light which reach bob's eyes and the red ones are those which enter the telescope parallel. The red lines entering the telescope parallel are supposed to be parallel as they leave the telescope, which means the telescope is in "normal adjustment" but I have no idea why... Yes, I know lenses are not supposed to be circular but they seem to work well enough. Also, yes, I am too lazy to make different wavelengths refract by different amounts. Also, yes I know that with the default settings, the green rays converge on the left, even though they aren't supposed to, I am just too lazy to find parameters which don't.
