Actually they do
eyes have an automatic selective focus,
Actually is very small and unlike a camera cannot be changed it's about F1.8-3.5 for focal range of the human eye.
You only true focus on about 1% of your vision and that is central like tunnel vision, outside blur is the same shape as your lens it's circular, your brain compensates for this.
A quick test example for you to try is:
1)Hold your index fingers next to each other
2)Close one eye look at the right index finger and bring the left closer about 6 inches.
3)Now look at each finger as you switch you should see the other go out of focus, it takes about half a second and might freak you out a bit. This is because of the muscles in the eye tensing to focus on close range objects, this tension causes eye strain and is why people need to take breaks from computers.
Also try this to freak your head out a bit:
1)Bring them together the same distance from the opened eye keeping the other closed.
2)Pull them apart about a foot look at the left one and the other should go out of focus and visa versa
This is the selective focus of your periphery, your brain tries to make up the image of a finger but it is not as sharp as the one your looking at, a camera however gets everything at the same range in focus and does not suffer with this.
If you want to really freak out the human eye has a blind spot,
1) Keeping your fingers together and level close your right eye
2) Look through your left eye at your right index finger
3) Starting together move the left index to the left and level slowly your finger tip will disappear at a certain spot once found try wiggling the tip and it should be invisible... freaky huh this is because the brain paints in the blank spot much like a clone stamp and because the majority of the image seen is the backdrop your index finger is literally chopped out this is compensated for with two eyes but still freaky eh
Photosensitive cells compensate automatically for low light conditions in fact your eyes have rods to help see in lower light conditions and cones for day and each are more sensitive to different colours this switching of cells are akin to your ISO
Although we work at speed of a blink in classical terms our eyes have a frame rate.
When looking at a wheel picking up speed when the revs per minute reach out frame rate the wheel appears to slow and reverse direction. (Cool note it's about 60fps pigeons can see a lot faster than us and in fact see films as slide shows)
Our aperture is variable by pupil dilation to let more light in, doctors often check pupil dilation with a light when light is shone on our pupil our eyes dilate to compensate so we can still see at the right light levels.
It's so fast you don't even notice, this image demonstrates.
Looks like they are different but actually
They are the same this is because your brain is used to adjusting your aperture (Dilation) for surrounding shadows and even does it faster than you can think.
This stuff interests me so I can go on for ages but I think I will end it here, basically as close to photo real as you can get it the better for just general realism.