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

The distance measuring device is your brain and the fact you have two eyes.

The brain calculates the distance of an object by measuring the difference betweem the images the eyes receive.

Close one eye, then the other. Things that are closer shift around more than those further away.