When your iris changes in size from light why does does the area we can see not change?
In: Biology
Imagine if you held a hole in front of a flashlight. If the hole is very close to the bulb/LED, then it doesn’t really matter how small the hole is (as long as it’s larger than the bulb). The area of light stays the same size because you’re not blocking any light. If you moved the hole further away from the light source, then it starts changing the size of the area.
Similarly, the iris is very close the the focal point, which is where all the light rays converge to a point. Since the light is already concentrated around a tiny point, the size of the iris is always much larger than that point, so light coming from outside of the field of view never would’ve hit your retina regardless of how big your iris was.
Instead, the extra light is coming into the eye from a different angle, but is getting focused to (almost) the same spots in the retina. So instead of getting a wider view, you just get more light.
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