There are various aspects of lens that effect the photographs.
Among them the most misunderstood is the focal length. Very often it is used to get close to the subject (zoom in), but that is not the sole purpose of it. One of the primary effect of changing focal length is on the relative size of objects in the foreground and background. The smaller the focal length the more is the order of relativity. The larger the focal length, the lesser is the order of relativity.
What it really gives, is the fact that with lower focal length, the distance between foreground and background elements is more as compared to larger focal length, in the photograph.
Another surprising behavior is, "if you keep the size of subject fixed as framed in your camera, then depth of field is largely immune to focal length changes and would change only with aperture"
Among them the most misunderstood is the focal length. Very often it is used to get close to the subject (zoom in), but that is not the sole purpose of it. One of the primary effect of changing focal length is on the relative size of objects in the foreground and background. The smaller the focal length the more is the order of relativity. The larger the focal length, the lesser is the order of relativity.
What it really gives, is the fact that with lower focal length, the distance between foreground and background elements is more as compared to larger focal length, in the photograph.
Another surprising behavior is, "if you keep the size of subject fixed as framed in your camera, then depth of field is largely immune to focal length changes and would change only with aperture"
