How does the eye know when the image is in focus? There is distance measuring device, only light entering the eye. No outer feedback to be sure that focus is in fact focus not something the eye think is focus.

Question

Thank you all for your respons and upvotes.

I can now see and focus on the answer of my question 🙂

In: 3993

Answer 1

Some quality responses from several commenters but I feel like a true ELI5 is missing. Here’s my take – How does the eye know when the image is in focus? How does the heart know what the heart wants? Why do birds suddenly appear, every time you are near? If a tree falls down in a forest and no one is around to hear, does it make a sound? How do I know if I’m a raging alcoholic?

Notice a pattern?