Exercise 10 - Focal lengths

For this exercise I have went to the sea shore and took some pictures of the stones. I am still in doubt, whether it was a good choice of the object for this exercise and the depth of field was enough to show the difference.

The first shot was taken at 18mm focal length (the aperture set at f/10 and with shutter speed 1/160s).

The second shot was taken at 85 mm focal length (aperture at the same f/10, shutter speed adjusted to 1/125) .

Maybe it is not that obvious at first glance, but when looking at both shots closer that first shot is more distorted and has more depth of field, while the second one looks a bit flat. I would say that I like the first one more. I should use my wide angle lens next time, which can be set to 14mm and this would make pictures like this one more interesting. 

The other thing that I noticed was that the second shot's angles are more blurred, though aperture was set at the same f/10 for both shots.