The directions arrow<span> is </span>always<span> going the wrong </span>way<span>.</span>
<span>Wave energy is an idea that Robert Hutchings Goddard introduced in his “Further Developments” to his research "A Method of Reaching Extreme Altitudes" </span>
It is round or say spherical to widen the range of photography and it is designed to focus the image as the ray are coming from infinity so !!
I am not an expert of camera but ya it is the main theme !!