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I'm trying to explain what causes an image to be distorted when seen through a water droplet. Specifically, my example is that of a drop of water on a car window. We can see that the image is reversed, which I understand as I take the droplet to act like a planar-convex lens. However, the image is also heavily distorted, it looks pretty curved/rounded, especially near the edges. I'm having issues explaining using sources, formulas, and to overall give a more formal explanation.

Could anyone help? All I can find online is about the magnifying effect of the droplet. Thank you ! (this is my first post, sorry if I tagged wrong or something like that)

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    $\begingroup$ It's called refraction. The same phenomena your planar-convex lenses use. $\endgroup$
    – DKNguyen
    Commented Apr 6, 2023 at 22:51
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    $\begingroup$ I am a bit rusty with this. But from what I remember, all this stuff with perfect lenses is idealisation. You should already be surprised that you can see anything at all, as different parts of a lens may have different focal distances, which blurs the image. The fact that it is distorted is not a surprise at all. To see what actually happens, you need to consider an actual shape of a drop, carefully take into account refraction angles and see what kind of image is formed. $\endgroup$
    – Dr.Yoma
    Commented Apr 6, 2023 at 22:56
  • $\begingroup$ @DKNguyen I think the OP understands that part. She is asking about the distortion... which is, of course, explained quantitatively in applied optics textbooks. The challenge is to explain that in a "short" answer. One can model it quite easily with a raytracing program, though... experiment with different shapes and see what it looks like. $\endgroup$
    – FlatterMann
    Commented Apr 6, 2023 at 22:57
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    $\begingroup$ sounds like an aberration. $\endgroup$
    – JEB
    Commented Apr 6, 2023 at 23:12
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    $\begingroup$ @StevanV.Saban Well, even a sphere isn't really the shape you want, I believe. Hence aspherical lenses. A very particular shape without a name as far as I know. $\endgroup$
    – DKNguyen
    Commented Apr 7, 2023 at 14:40

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