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what is the F stop of our eye's pupils?

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Google is your (and my) friend. Just look for 'f ratio of human eye' and in the first hit you'll find this:

"Computing the f-number of the human eye involves computing the physical aperture and focal length of the eye. The pupil can be as large as 6–7 mm wide open, which translates into the maximum physical aperture.

The f-number of the human eye varies from about f/8.3 in a very brightly lit place to about f/2.1 in the dark.[8] The presented maximum f-number has been questioned,[9] as it seems to only match the focal length that assumes outgoing light rays.[clarification needed] According to the incoming rays of light (what we actually see), the focal length of the eye is a bit longer, resulting in maximum f-number of f/3.2.

Note that computing the focal length requires that the light-refracting properties of the liquids in the eye are taken into account. Treating the eye as an ordinary air-filled camera and lens results in a different focal length, thus yielding an incorrect f-number."
 
And our brains do so much post-processing or real-time processing, that make most scenes much more detailed and full of information even if theoretically a camera can out-resolve the human eye...
 
The brain doesn't do anything as boring as restrict itself to what the eyes actually record. The visual system interprets the data it gets from the eyes and replaces the data with it's best guess for what it expects to see. It's why optical illusions work. It's also why human beings make such appallingly bad witnesses - they tend to remember and see what they expect to see, not what was actually there.

--
StephenG
 
Are rods noisier than cones?

How many MP does 20/20 vision equate to?

What's so funny about vitreous humor?
 
emax said:
What's so funny about vitreous humor?
Click to expand...
"I'm seeing spots in front of my eyes.."
"That sounds bad. Have you seen a doctor?"
"No. Just these spots... sort of floating... in front of my eyes..."
--
Regards,
Baz

"Ahh... But the thing is, they were not just ORDINARY time travellers!"
 
Yes, but a lot of the processing takes place in the eye itself. The retina is more like a part of the brain than a sensor or film. The rate of firing of a neuron in the retina influences the rate of firing of surrounding neurons.

In the central area of vision this attenuates detail and enables to perceive both big contrasts and fine nuances (but not at the same time). E.g. you can see details on the moon more easily when it is on the day sky than with a dark background at night.

In the peripheral vision the neurons interact in a way which enhances the perception of movement.
osage_archer said:
And our brains do so much post-processing or real-time processing, that make most scenes much more detailed and full of information even if theoretically a camera can out-resolve the human eye...
Click to expand...
 
Mike Yorkshire said:
You might like to read through this > > >

http://www.clarkvision.com/articles/eye-resolution.html

It claims the human eye is around 324 to 576 Megapixels.
Click to expand...
That assumes that the high central resolution is duplicated all over the field, which it isn't really.... because our perceptions of a scene are built up gradually, by scanning the maximum rez area of the retina over the entire field.

The Cambridge in Colour link, already cited, is much more realistic in camera terms...

http://www.cambridgeincolour.com/tutorials/cameras-vs-human-eye.htm
Mike Yorkshire said:
The article also claims that a dark-adapted eye is around 800 ISO
Click to expand...
Sounds about right.
--
Regards,
Baz

"Ahh... But the thing is, they were not just ORDINARY time travellers!"
 
You could also argue that the resolution of the eye is much higher than that because when you look at someting you can move - you look from a distance and take a close look.

I think the eye is not really much like a camera. Eye is not a machine - vision is a function of a whole living organism.
 
osage_archer said:
Google is your (and my) friend. Just look for 'f ratio of human eye' and in the first hit you'll find this:

"Computing the f-number of the human eye involves computing the physical aperture and focal length of the eye. The pupil can be as large as 6–7 mm wide open, which translates into the maximum physical aperture.

The f-number of the human eye varies from about f/8.3 in a very brightly lit place to about f/2.1 in the dark.[8] The presented maximum f-number has been questioned,[9] as it seems to only match the focal length that assumes outgoing light rays.[clarification needed] According to the incoming rays of light (what we actually see), the focal length of the eye is a bit longer, resulting in maximum f-number of f/3.2.

Note that computing the focal length requires that the light-refracting properties of the liquids in the eye are taken into account. Treating the eye as an ordinary air-filled camera and lens results in a different focal length, thus yielding an incorrect f-number."
Click to expand...
Right - f/3.2-f/4 is about right.

--
Lee Jay
(see profile for equipment)
 
Barrie Davis said:
Barrie Davis said:
The article also claims that a dark-adapted eye is around 800 ISO
Click to expand...
Sounds about right.
Click to expand...
Not to me. My dark-adapted vision can capture far more through the same optics than my camera at ISO 12,800 with a 1 second exposure. Given that our eyes can integrate only around 1/10 of a second, that means we're over 128,000 when fully dark adapted. In fact, my own experiments suggest it's more like ISO 500,000.

--
Lee Jay
(see profile for equipment)
 
ljfinger said:
Barrie Davis said:
Lee Jay said:
The article also claims that a dark-adapted eye is around 800 ISO
Click to expand...
Sounds about right.
Click to expand...
Not to me. My dark-adapted vision can capture far more through the same optics than my camera at ISO 12,800 with a 1 second exposure. Given that our eyes can integrate only around 1/10 of a second, that means we're over 128,000 when fully dark adapted. In fact, my own experiments suggest it's more like ISO 500,000.
Click to expand...
I used to think it was higher, too, but have read so many worthy authorities that didn't put it above 2000 ASA/ISO I have been obliged to revise my opinion.... Besides, my eyes are getting old, and I can't see the crack under the darkroom door anymore, no matter how long I spend in there. :-(
--
Regards,
Baz

"Ahh... But the thing is, they were not just ORDINARY time travellers!"
 
Barrie Davis said:
ljfinger said:
Barrie Davis said:
Barrie Davis said:
The article also claims that a dark-adapted eye is around 800 ISO
Click to expand...
Sounds about right.
Click to expand...
Not to me. My dark-adapted vision can capture far more through the same optics than my camera at ISO 12,800 with a 1 second exposure. Given that our eyes can integrate only around 1/10 of a second, that means we're over 128,000 when fully dark adapted. In fact, my own experiments suggest it's more like ISO 500,000.
Click to expand...
I used to think it was higher, too, but have sread so many worthy authorities that didn't put it above 2000 ASA/ISO I hve been obliged to revise my opinion.... Besides, my eyes are getting old, and I can't see the crack under the darkroom door anymore, no matter how long I spend in there. :-(
Click to expand...
I keep hearing that too, but try your own experiment:
  • Get dark adapted (10 minutes in the dark).
  • Look around in a dark location.
  • Shoot at shot at 1/10th, f/3.5 with your camera.
  • Adjust ISO on the camera until what it's capturing is about what you're seeing.
I'd bet you won't be able to get that high.

--
Lee Jay
(see profile for equipment)
 
ljfinger said:
Barrie Davis said:
ljfinger said:
Barrie Davis said:
Lee Jay said:
The article also claims that a dark-adapted eye is around 800 ISO
Click to expand...
Sounds about right.
Click to expand...
Not to me. My dark-adapted vision can capture far more through the same optics than my camera at ISO 12,800 with a 1 second exposure. Given that our eyes can integrate only around 1/10 of a second, that means we're over 128,000 when fully dark adapted. In fact, my own experiments suggest it's more like ISO 500,000.
Click to expand...
I used to think it was higher, too, but have sread so many worthy authorities that didn't put it above 2000 ASA/ISO I hve been obliged to revise my opinion.... Besides, my eyes are getting old, and I can't see the crack under the darkroom door anymore, no matter how long I spend in there. :-(
Click to expand...
I keep hearing that too, but try your own experiment:
  • Get dark adapted (10 minutes in the dark).
  • Look around in a dark location.
  • Shoot at shot at 1/10th, f/3.5 with your camera.
  • Adjust ISO on the camera until what it's capturing is about what you're seeing.
I'd bet you won't be able to get that high.
Click to expand...
None of my cameras go above 3,200-ISO
--
Regards,
Baz

"Ahh... But the thing is, they were not just ORDINARY time travellers!"
 
I think it depends on what you mean by dark adaptation. The central part of the retina with cones is much less adaptable to lowlight but perceives more detail than the peripheral vision based on rods. When you walk after sunset and it gets gradually darker at some point you will not be able to distinguish between red and dark grey. At about the same time you will not be able to read normal sized print. But it can get much darker before you lose the ability to keep to a path and not to bump into trees.

In some photographic darkrooms you can see a little after adaptation - in a light which is so low that you can handle high ISO film safely. (Panchromatic films can be handled in low green light which makes some visual orientation possible beacause the sensibility of the rode vision at this wavelength is enormous compared to any film).
ljfinger said:
Barrie Davis said:
Lee Jay said:
The article also claims that a dark-adapted eye is around 800 ISO
Click to expand...
Sounds about right.
Click to expand...
Not to me. My dark-adapted vision can capture far more through the same optics than my camera at ISO 12,800 with a 1 second exposure. Given that our eyes can integrate only around 1/10 of a second, that means we're over 128,000 when fully dark adapted. In fact, my own experiments suggest it's more like ISO 500,000.

--
Lee Jay
(see profile for equipment)
Click to expand...
 
Barrie Davis said:
ljfinger said:
Barrie Davis said:
ljfinger said:
Barrie Davis said:
Barrie Davis said:
The article also claims that a dark-adapted eye is around 800 ISO
Click to expand...
Sounds about right.
Click to expand...
Not to me. My dark-adapted vision can capture far more through the same optics than my camera at ISO 12,800 with a 1 second exposure. Given that our eyes can integrate only around 1/10 of a second, that means we're over 128,000 when fully dark adapted. In fact, my own experiments suggest it's more like ISO 500,000.
Click to expand...
I used to think it was higher, too, but have sread so many worthy authorities that didn't put it above 2000 ASA/ISO I hve been obliged to revise my opinion.... Besides, my eyes are getting old, and I can't see the crack under the darkroom door anymore, no matter how long I spend in there. :-(
Click to expand...
I keep hearing that too, but try your own experiment:
  • Get dark adapted (10 minutes in the dark).
  • Look around in a dark location.
  • Shoot at shot at 1/10th, f/3.5 with your camera.
  • Adjust ISO on the camera until what it's capturing is about what you're seeing.
I'd bet you won't be able to get that high.
Click to expand...
None of my cameras go above 3,200-ISO
Click to expand...
Shoot in raw. and push in post. If 800 is right, you'll have no problem getting there without pushing.

--
Lee Jay
(see profile for equipment)
 
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