Optics Problem: What optical instrument does this?

[e101101]

Homework Statement

Imagine you are using this (2 converging lens system) to image a stellar object with an angular spread of α. (This means, that the object is so far away, that the rays coming from the top of the object arrive at the lens system as plane waves at one angle, and the rays coming from the bottom of the object also arrive at the lens system as plane waves, but at a different angle, and the difference between those angles is α.
Describe the characteristics of the “image”. What optical instrument does this remind you of?

Relevant Equations

none

Im thinking that this is a telescope, but I am having a lot of trouble answering this question.

If the plane waves arrive at different angles, wouldn't the image be distorted?Would the lenses possibly be spherical because of this?

 

[BvU]

Make some sketches. Where do plane waves converge ?