Exercise: Focal Lengths - Different viewpoints

This exercise required me to take two photographs of the same object, (in this case a fenced off tree) firstly with a long focal length and then a short focal length. It also required me to make sure that the subject took up roughly the same amount of space within the frame. The first shot was taken from over 10 metres away; the second shot from no more than 2 metres. Although the exercise required me to walk in a straight line toward the subject between shots, I did have to adjust the angle of the second shot slightly in order to get a similar angle on the fenced off tree in the background. I needed to do this to enable me to show the disparity - from one image to the next - in apparent distance between the two trees .

200mm f/7.1

This shot was taken from a distance and zoomed in at a focal length of 200mm (efl: 300mm) Note that the fence around the tree in the background appears to be around 75% of the size of the fence in the foreground - it appears to be quite close. The field of view is also quite narrow, as you might expect from a long focal length lens.

30mm f/7.1

This second shot was taken with a comparatively wide-angle of 30mm. Again, the fence in the foreground takes up most of the frame, but now the fence in the background appears much smaller, only about 25% of the size of the fence in the foreground and seems much further away. The shorter focal length also provides a wider angle of view, so much so I couldn't get my shadow out of the shot! What is also noticeable is that the background is slightly more in focus in this wide angle shot, even though the lens aperture (f-stop) setting is the same. what is puzzling me at the moment is, is this due to the fact that the background seems closer in the longer focal length image, and hence seems more blurred, or is it because the actual physical aperture size is greater in the wider angle lens? 

The compression effect of the longer lens compared to the wide angle lens is quite remarkable and it is an interesting feature to remember when composing shots. At first I didn't quite believe that the images were of the same pair of fenced trees, but looking closely at the breaks in the fence you can see that they are indeed the same pair.