Let me suggest a straw-man hypothesis for the Calvine photo, let's see if it can be torn down. It's based primarily on the focus of different objects.

1. Closest to the camera is the "UFO," a small object held up by one or more strings. Possibly a small kite. The camera's focus is set for this object.

2. Next closest to being in focus are the tree branches, farther away than the UFO.

3. Next closest is the fence, well beyond the tree branches.

4. The most distant object seen, the Harrier jet, is out of focus.

The principal take -away is, the presumably distant UFO is in focus while the actually distant jet is not. We still don't know what kind of camera and lens was used, so we can't quantify the depth of field. We also don't know the f/stop used, which determines the depth of field. The analysis of Andrew Robinson suggests that it was probably taken with a small 35mm camera, with a lens around 50-110mm focus. In other words, very ordinary.

If the UFO were at least as far as the tree leaves or the fence are from the camera, it, too, would be out-of-focus.