If you spend quite some time watching videos in YouTube then I’m pretty sure you have seen at least one video from Corridor Digital. They are a bunch of digital film makers who use compact video cameras (Scarlet and Canon SLRs) to create graphic-intensive videos. Since they are using lenses with the cameras, they are pretty knowledgeable in explaining the basics to those unfamiliar with lenses, despite not really specializing in photography.
In this video, Niko explains the basics about lenses, why they are expensive and how they generally work. For around 8 minutes you’ll learn a lot about why a good lens is better than an expensive camera.
Source : YouTube