Is night vision blurry?

Question

Because to see in the dark, your pupils (irises, or whatever) get bigger to allow in more light. But the clearest images are produced by pinhole cameras (where the hole is as small as possible).

So is our night vision actually inherently blurry because of the wider aperture? Or do our eyes focus it to normal anyway?

Also I just realised that this probably isnt the right category for this question, but physics people are generally quite knowledgeable about a wide range of things anyway!

Answer 1

Night vision is not inherently blurry. A camera with a smaller aperture doesn't produce a sharper image, it just produces an image with greater depth of field (depth of focus). With some difficulty and a careful setup, you could demonstrate that same effect with night vision. Actually, that sounds like a good science fair project.

With a pinhole, you're not really focusing. Using a lens allows you to gather more light by focusing.

Night vision uses only the rod cells of the eye, which are sensitive enough to detect a single photon. Only with a quantum mindset can you imaging focusing a single photon.

Answer 2

Your eyes are probably doing something weird. There's a lot less light and contacts and glass obscure that light essentially in the opposite way your eyes interpret it to make it clear. Your eyes are really complex; they test you in a brightly lit room, I think because it's 'optimal'. Your eyes may very well see things differently in the dark. My guess behind this is that during the day there as a lot of light coming at you, a lot of reflection of color for your eyes to interpret. With how little of it is coming in at night, your eyes might process it better (or it's worse and you need a stronger prescription).