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I observed when a helicopter rotor or fan is spinning the blades blur making it impossible to count the blades, but after a certain speed the blades seem to become visible making it possible to count the blades. Cameras can also do this better.

Do human eyes have a frame rate? What is that called and the most a person can see?

This video in the link shows how these blades seem not to move by timing with the cameras frames rate.



marked as duplicate by Muze the good Troll., Community Apr 27 at 21:14

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  • $\begingroup$ The term you want is "flicker fusion rate". For humans, it's about 30 frames per second, though it varies somewhat between individuals: ps://en.wikipedia.org/wiki/Flicker_fusion_threshold $\endgroup$ – jamesqf Apr 27 at 18:17
  • $\begingroup$ @jamesqf I revised it so your comment can be an answer. Thanks $\endgroup$ – Muze the good Troll. Apr 27 at 19:11
  • $\begingroup$ @BryanKrause TEKKEN? $\endgroup$ – Muze the good Troll. Apr 27 at 21:12