Focal lengths and different view points

On this exercise we simply demonstrate how the background will change (will be compressed) when we change focal length.

Both pictures were taken from different spot but our subject to background distance did not change. For the first picture we were closer to our subject and we used wide focal length. The second picture was taken from distance by using telephoto lens. As we can see our subject is the same size in both pictures. The only thing that changed is the background. In the wide focal length picture it is less compressed than when we used telephoto. 

200 mm

17 mm