Eyesight

[Ap30x]

Does anyone know why when looking at something close up does further away look blury, and looking at something further away up close becomes blury.
I have never noticed this before so it’s got me over thinking why this is😂

It’s because your eye muscles tense a variable amount to change the shape of the lens in your eye. The change in shape means you focus on the item you’re looking at (be it far away or close up). You can’t focus on far away and close up at the same time (although there is obviously a middle ground when you’re scanning a room for example)

You get the same effect in photography, it is called 'depth of field'. When you see a portrait where the person is in sharp focus, and the background is a blur, it is because the photographer has set the aperture to achieve this effect. My samsung phone can do the same effect digitally. The iris of the eye widens and narrows for the same effect. If you google depth of field there are loads of websites explaining it better than I can.