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

It’s simple: it guesstimates based on how clear the image is.

I was looking at an image on my second screen and, because I was unable to focus it AND it looked precisely like being unable to focus an image that is originally sharp, I gaslighted myself into thinking I need new glasses. Then I put in another app that did show things sharply enough that I went “Nevermind!”