I want to emphasize one point that has been mentioned. Please look at this photo, in which the man is Picasso,
The bright line (yes, that is one single line) is a camera's view of Picasso's torch, also a "tracer". The line is so long and even, only because the
exposure time of the camera was very long, to the extent that during this period Picasso was able to draw the whole "bull" in the air. What the camera "saw" is a bull, while the human eye would of course only see the moving torch.
There is of course similarity between the way in which the human eye works and that of the camera, but such similarity (not identity) only exists in the optical part of the human eyeball, the neural mechanism of the eye and visual cortex being missing in the case of the camera. It a complex subject that perhaps psychologists on percerption know much about, but it is certain that what a camera sees is not exactly what a human sees.
Another example: a human can be dazzled by bright muzzle flash of a cannon, but
not by a photo of the muzzle flash, meaning that the camera cannot reproduce enough gradations of bright light that a human eye can tell.
So movies of tracers and gun camera film are not good arguments when tracers are discusssed, unless it is the aim of CoD to simulate only the camera's view.
Although I myself have never in person seen tracers being fired, I have doubt that the "light rod" of each tracer should be of both the same brightness and the same width from beginning to end.
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