What’s the F-number of the Human Eye?

Ever wonder what the f-number of your eyes are? It can easily be calculated using the human eye’s focal length (~22mm) and physical aperture size. Here’s what Wikipedia has to say:

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. The presented maximum f-number has been questioned, as it seems to only match the focal length that assumes outgoing light rays. According to the incoming rays of light (what we actually see), the focal length of the eye is a bit longer, resulting in minimum f-number of f/3.2.

The article also notes that the eye cannot be considered an ordinary air-filled camera since it’s filled with light refracting liquid.

F-number: Human Eye (via Reddit)

Image credit: eye 172/365 by attila acs

  • Happy_Tinfoil_Cat

    What’s the sensor size? How many megapixels… I mean rods / cones?

  • Kyoshibecker

    I was always told that it was around a 5.6 as seen on a 35mm dlr

  • Adam Harrison

    No word on the eye’s ISO speed?

  • Mansgame

     How good is the eye’s Vibration Reduction?  That’s gotta be good for at least 3 stops

  • Paul O’ Hanlon

    How about noise performance? Priorities guys! :)

  • kenn

    Exactly how high was the model who posed for this “eye shot”, must have been suffering from glaucoma.

  • Alex Kris K Vich

    I wanna know at which f-stop my eye starts picking up chromatic aberration! 

  • Grog

    my left eye is Expeed 3, my right is digic 5+.. i need a new firmware!! please help!

  • Guest

     I know it’s got to be 3D-capable

  • Com

    Not one person commented on the sheer fact that we as humans were able to figure this out, how far we’ve come. All of you were talking about camera related things, hahaha. It’s fantastic.

  • Blindman

    Mine need to be sent back to the manufacturer for calibration :/

  • Greg Planchuelo

    Does this mean that in brighter places, when the pupil gets smaller (higher f number) we see with more depth of field?


  • Stephan Zielinski

    According to the Wikipedia article on the retina: “The entire retina contains about 7 million cones and 75 to 150 million rods.”  Obviously, we’ve got an internal demosaicing algorithm from hell to make sense of this.

  • RioRyan

    It definitely does, and your eyes know this. If you’ve ever tried to look at something really close up, to the point where your eye is straining, your pupil will get smaller to increase depth of field in an effort to focus. Try it in front of a mirror, or watch somebody else do it!

  • Happy_Tinfoil_Cat

     I guess that means I won’t be upgrading anytime soon. Come on Canon, I want a bionic eye… make it the “Wonder Camera”.

  • B Knapstad

    What’s the dynamic range?

  • MyNAmeisFree

    Exactly. You don’t really “see” what your eyes see so pixels in the end wouldn’t matter too much

  • Zak Henry

    Makes me wonder what advantages a fluid filled camera would offer

  • Guest

    It cannot represented in (shutter)stops unit because the eyes don’t work that way. But they do have VR mechanism, very effective in fact.

  • Guest

    With built HDR, it’s about 20 f-stops.

  • Suman0102

    although there are a TON of rods and cones, not all of those would count as effective pixels in a way since not all of them are used when the brain translates them. So kinda hard to say.

    But according to cambridge: “based on the fact that at 20/20 vision, the human eye is able to resolve
    the equivalent of a 52 megapixel camera (assuming a 60° angle of view)”

    But since we only see sharp details in a small part of the actual field of view, its essentially 5-15MP.

    Anyways, more details here:

  • Suman0102

    its amazing how good the eye is at that. i mean, you could go for a run in the park and everything is very smooth (as opposed to footage from a camera strapped to one’s head)

  • Suman0102

     god or yo mama? lol

  • Suman0102

     like a boss!!

  • waqasnasir

    A single eye does what a series of lenses cannot do .. how amazing the eye is ..

  • Shawn Thompson

    I do not know a whole lot about optics however I do know what we see is
    more an interpretation of the brain vs the eyes actual capacity. When
    you think of it it seems amazing that 20-20 vision can even look sharp
    considering each eye can only focus on a tiny area, and not to mention
    the fact that it is projected upside-down etc and each eye has a huge
    blind spot in the middle. essentially in each eye you only have a ring
    of sight while the centre is blind so it fascinates me that we in fact
    see as well as we do.  A way to prove that your eyes are actually blind
    in the centre is to just look up at the stars at night, and block one
    eye. As the star heads into the centre of that eyes field of vision it
    will vanish because there are no rods or cone cells in the centre of the
    eye since the optic nerve is there.

    In astronomy this is done because if you are looking through a telescope
    and stare up at a star or planet through the centre of your eye it will
    disappear if it is in the centre of your field of vision because each
    eye has a massive blind spot.

  • kendon

     and what exactly would that be?

    apart from the fact that you are comparing a (series of) lens(es) to a lens-sensor-developer-interpreter combination, which the human eye and the brain are.

  • MannDaryl

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  • Jack

    VR?! The human eye CLEARLY uses IS!

  • Bill Smith

    Gee, they could have used an eye that isn’t so bloodshot! It made me feel ill!

  • Wolf Cocklin

    Problem is after reading this thread with my eyes, my brain drive is now full, I need an XQD card and slot to process this.

  • purplepick

    How is the focal length only 22mm? We have an incredibly wide FOV.

  • Guest

    install magic lantern. you have more controls, one of them being manual gain control for audio input (ears) :))

  • Guest

    And, probably, a quad-core processor, to process the new information … 

  • Daniels

    VR it is, cant see the grain haha!

  • jerry

    according to the article it says that the widest aperture is f2.1. but then at what iso because when you calculate the human eye to what a digital camera captures at that F stop with no noise it is ridiculously inaccurate. I would really like to find the real F stop of a human eye in relation to digital Image.

  • pj

    Is our eyes a Canon or a Nikon? lol