When your iris changes in size from light why does does the area we can see not change?
In: Biology
Because light travels in all directions at once.
If you shine a flashlight through a hole, you sort of get what you’re talking about. Some light, and a shadow.
But that’s a single source of light moving a single direction.
Your iris is more like the window in your room.
You can go to almost any part of the room and look out the window. But what does “look out the window” really mean? Your eyes don’t emit light, they only receive light. So looking out the window actually means going to a place and observing the light passing through the window and reaching your position. That includes reflected light, so the light bouncing off a car, through the window, and reaching you.
So, say you close your window mostly, leaving just a 6-inch hole in the middle. You can still go to any of the places you could goto before to see out that hole.
The only difference is, now, as you walk around, through this smaller hole, you can see fewer things at a time.
Say, there’s a tree outside your window, a fence further back, and a house even further back.
If used to be, before you covered most of your window, you could stand anywhere in your room pretty much and see the tree, the house, and the fence, all at once.
But, now that you’ve covered most of the window, you can still see everything as you move around, but you see fewer things through the hole at once. Maybe now, from one spot, you can only see some tree leaves, or a section of fence, or a region of house.
That’s mostly what opening and closing the iris does: it allowed your eye to focus.
When your window is very large, as you move about the room, the thing that’s most stable in your vision is t
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