An unsharp light dot
That video shows that the
lens was
out of focus. (it actually never was able to lock onto the object when the person zoomed into the object). Which explains why the object changes shape. The dot like object's light, get's distributed into a larger surface. In this case a romb like looking object. The camera/lens is trying to focus sharp... its autofocus going back and forth
The
shape of the aperture blade (the hole through which the light travels) is what decides the outer boundaries of the "object" you see in the video. The camera with the video was made with, seem to have had a very
simple aperture (diaphragm)
construction of just 3 or 4 blades, making it look
romb-like.
The more aperture blades a lens has, the rounder the "blob" (blurry objects: such as from peak highlights, street lamps, a bright star or planet, candle, moon, sun, etc, which are way out of focus. Usually when the lens is set to a close point at a close distance, while distant dot-like objects at infinity, become blurry transforming into blobs (also being part of the "bokeh" in a photo).
In normal camera lenses you have at least 5 blades or more. Even better 8-9 blades in more expensive lenses. Some lenses can exhibit up to 16 aperture blades, making everything that is unsharp in the background, look buttery smooth.
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Sometimes, or rather, quite often you find
spots projected within those onion rings; those are
dust particles in/on/between the lens elements which get projected.
The rings inside the "surface", are called
"onion rings", which are caused by the lens' material and how/or that it was molded and glued. Often, in simple lens constructions - as well in complicated zooms, we find "aspherical molded and glued" lens elements, which causes these "onion rings". This happens when the
micro structure of the lens elements is more uneven (in cheap construction like cheap lenses, web cams, cheap zoom lenses) - which are often made out of optical, molded plastic, not glass.
Yet, it can also happen in so called aspherical lens elements made of glass (often molded into the proper shape) instead of the much more expensive and time consuming way of grinding it carefully down to the desired aspherical shape.
The phenomena of "onion rings" is highly disliked in the photography community.
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