Eli5:If the pupil expands and shrinks depending on light, why dosent our field of view change with the pupil?


Eli5:If the pupil expands and shrinks depending on light, why dosent our field of view change with the pupil?

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5 Answers

Anonymous 0 Comments

I think it would be your depth of field that would change, wouldn’t it?

Does the human eye have differing depth of field with pupil/aperture size due to light?
byu/wakanooms inaskscience


Anonymous 0 Comments

It does, slightly. And as Buck said, it’s more that your depth of field changes than your field of view.

But you also have to be aware that what you “see” isn’t as closely related to the optics of your eye as you’d assume.

Your brain is continuously building a 3D understanding of the entire environment around you based on audio and video information, stitching all those data points together. Your understanding of the environment is more like a 3D HDR reconstruction of what your eye can see than it is like a photograph. Your eyes will continually adjust to things like shadows so that you can know information about what’s under the table, as well as above the table, even though the top of the table is bright enough that your eye doesn’t have enough dynamic range to see that and the shadows at the same time.

The same kind of thing happens with your brain essentially focus stacking the environment. Your eye can’t keep the TV and your table both in focus, but your brain keeps track of what it knows is on both at once.

Anonymous 0 Comments

Because the pupil doesn’t control field of view, it controls the amount of light that reaches the retina. To change field of view, the cornea and/or lens would need to change.

Anonymous 0 Comments

Hey listen, this isn’t going to be an actual exact explanation, so I hope they don’t delete it, but if you want to do a cool experiment regarding this, make a pinhole camera for observing the sun using a cardboard box. Try it in midday when the sun is out and there’s no cloud interference and you’ll get a great image of the sun on the inside of the box. Then, open up the hole a little more and look again. This is a perfect analogy for the situation you’re asking your question about. What you’ll get is just a brighter image of the sun, not a bigger or smaller image or focused differently or anything. You just get a brighter image.

Don’t open it too big or it’ll start to get really blurry though.

edit: you know come to think of it if an actual 5-year-old ask me this question this would be part of how I explained it to him, so I guess it actually is a legit answer and I shouldn’t have worried about it being deleted.

Anonymous 0 Comments

The pupil is just like the aoerture in a camera. It roughly surrounds the point at which on-axis light converges as it travels through the eye between the cornea (lens) and retina (like a camera CCD).

When the pupil contracts, it blocks out off-axis light (light that enters the eye on a path not directly between its source and the convergence point I mention above). Like in a camera, reducing off axis light darkens and sharpens the resultant image.

This is why people who wear glasses often don’t need to wear them on a bright sunny day. Their contracted pupils turn their eyes into pinhole cameras which produce sharper images.