I'm searching a long time for an answer without helpful results. Here are some examples of unhelpful answers:
The lenses bend the light in such a way that they appear bigger — that's not an answer at all, because the question is what is that “such a way”.
The eyepiece magnifies the image the same way a magnifying glass does — instead of explaining, he is saying that it's the same as another thing that I may not understand how it works, or why it is the same.
Describing where the light converge and diverge — it's necessary to explain how do that cause magnification.
Talking about the advantages of reflecting telescopes over refractive, or other advanced topics, without explaining step one.
The most helpful thing will be, to show two diagrams of the paths of light in a telescope, one diagram of a telescope with a weaker magnification, and one diagram of a telescope with a stronger magnification, so the difference will be obvious.
So my question is why does an objective lens with a longer focal length cause the image to be larger, and why does an eyepiece with a shorter focal length magnify better. And I know that magnification means covering a larger angle when entering the eye. But my question is how do telescopes cause this.
And here is why I don't understand why an eyepiece with a shorter focal length makes the image appear bigger: Here f is the focal point, and there are two eyepieces, A and B. It seems that eyepiece B would magnify better for two reasons. First, because it deals with a smaller portion of the image. Second, if both eyepieces have the same bending power, then eyepiece B would give out rays that are stronger converging (because the incoming rays are less diverging), making it appear bigger (covering more arc degrees).
Links to articles or books that answer my question will be highly appreciated.