Quiz photos: photos suprise ... what is it?

[oli 80]

Hi everybody,
I think it's the underside of a mushroom

without google, seen in another post from forum

[Christophe]

Won!

Ckoi_solution.jpg (144.44 KiB) Viewed 1922 times

It's your turn !

[Christophe]

Not a photo quiz but an optical phenomenon to explain.

I have a motor with 4 threads distributed over a square.

When the engine is running, the circle of this "square" is not centered.

The phenomenon of non-centricity is better visible to the naked eye than in the photo. I did what I could:

20210812_174237.jpg (131.62 KB) Viewed times 1820

Why?

(I have the solution, it's not very hard to find but ... it intrigued me for a few minutes and still deserves a little thought)

[Christophe]

As specified, it is better visible to the naked eye, so it is not an optical effect of the photo ...

Take your brain!

ps: the vaccinated are not allowed to participate

[Christophe]

It runs on the RS:

quizz.jpg (335.43 KB) Consulted 1404 times

[oli 80]

Hi everyone here is one in the same genre or you have to understand


it took me a while to understand

[Christophe]

It's not a photo Quiz Oli since there is the answer...

[Obamot]

Not a photo quiz but an optical phenomenon to explain.

I have a motor with 4 threads distributed over a square.

When the engine is running, the circle of this "square" is not centered.

20210812_174143.jpg

The phenomenon of non-centricity is better visible to the naked eye than in the photo. I did what I could:

20210812_174237.jpg

Why?

(I have the solution, it's not very hard to find but ... it intrigued me for a few minutes and still deserves a little thought)

Already there is the deformation due to the optics (which is not well centered) then there is the retinal persistence when it turns?

[Christophe]

Almost but no...

[Obamot]

And why? Because there is a hole whose bottom is “light” and the other three “black”, suddenly when it turns, with retinal persistence, it gives the illusion that it is not centered: I am you good?