Approximating the human eye

Discussion in 'Beyond the Basics' started by selmerdave, Mar 9, 2005.

  1. selmerdave

    selmerdave TPF Noob!

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    I read recently in a photography book that the human eye seems to perceive motion at roughly 1/15th of a second. Objects in motion will appear about as blurred in a photo taken at 1/15th of a second as they do to the naked eye. I don't know whether many people agree with this but it makes some sense to me.

    I'm wondering if anyone knows of a similar equivalent for depth of field, or if anyone would like to guess one, say with a 50mm lens. f4?

    Dave
     
  2. Unimaxium

    Unimaxium TPF Noob!

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    Well my assumption is that human eye DOF would change like the aperture on a camera, as our pupils / irises contract and expand depending on the amount of light. But I bet this would be hard for anyone to notice anyway since our brains do a good job of compensating.
     
  3. panchromatic

    panchromatic TPF Noob!

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    The human eye stinks. Its our brains that do 90% of the "seeing", a good example of this is the blind spot test. Your brain takes most of the information and generates it. I always think of the human eye as a wide angle lens, and your DOF is quite small if focusing on something close and vise versa if looking at something far away... though your eye has very little edge to edge sharpness.


    --Ryan
     
  4. lazarus219

    lazarus219 TPF Noob!

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    well i know if you put a pen about 5cm from your eye and look at it, your eye will focus on the pen and everything will blur except the pen, i guess that DOF. I have been wondering about the eye since i got into photography- because i know video cameras still use the shutter to make each frame but i just figured your eyes are always open right? (like a shutter not open like it usually means)
     
  5. Hertz van Rental

    Hertz van Rental TPF Noob!

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    The problem is that we do not perceive everything the eye sees - and the eye is by no means very well designed - so any discussion on what the eye sees has to take the brain (and indeed psychology) into account.
    The information gathered by the eye is processed - and processing starts in the optic nerve (by the way it is constructed). The brain then filters and interprets this information and fills in any gaps - and also leaves out a lot.
    The shortest interval the brain can comprehend is 1/60th of a second but the eye can capture much shorter intervals. A flashgun going off can generate a light for less than 1/10,000th of a second. The eye catches this but the brain interprets it as 1/60th.
    The hardest thing to get to grips with is that colour, as we perceive it, does not exist outside the visual cortex.
    As for depth of field - this is affected by lots of factors in the eye. The lens changes shape, the pupil aperture varies, even the shape of the eyeball changes. The eye is doing all this constantly. And then, of course, the brain is involved. Not to mention the zones on the eye - the central area and the peripheral zone. Oh, and the blind spot where the optic nerve leaves the eye.... and the fact that light has to travel through a several layers of cells before it hits the rods and cones... and the capillaries that are in front of the light receptors...
    If anyone tries to argue in favour of 'intelligent design' as opposed to Darwin, just show them the human eye and mutter about 'bl**dy amateurs'. ;-)
     
  6. Rob

    Rob TPF Noob!

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    There may be no I in team, but there is a U in c%nt.

    Sorry, couldn't resist. :)
     
  7. panchromatic

    panchromatic TPF Noob!

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    i was not comparing anything to do with cameras, that is a total apples and oranges comparison. The camera does not plug in spots that are missing or covered (like the brain does.) You have blind spots, nerves and other things covering what you "see" and the brain "removes" them and replaces them with what it things should be there (BLIND SPOT). Cameras record what is there, if you have massive finger prints on your lens then your camera sees it. I never said the brain and eye do not work as one, in fact I said they do. I never said a camera was better than the human eye and brain, if my camera had a brain then it would be the best thing ever.

    next time read what i am saying before you post, and if you post do not put words in my mouth i do not appreciate it.

    and you definitly where trying to be a prick.
     
  8. thebeginning

    thebeginning TPF Noob!

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    this has been the only worthwile post in this entire thread. :-D

    ive never noticed my eye's (or brain, whatever) DoF...it's very hard to tell. but i think i do agree with the 1/15 thing. it seems so much faster, but once you think about it, it does make sense. your eyes just tend to follow things i guess, so it compensates for the blur.
     
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  9. DocFrankenstein

    DocFrankenstein Clinically Insane?

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    Don't anybody know physics here?

    To get the same bokeh in camera as the "human eye"
    Diameter of the pupil = diameter of the diaphragm

    Problem solved
     
  10. selmerdave

    selmerdave TPF Noob!

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    Isn't it a factor of the relative relationship rather than the absolute size? I think in room lighting my pupil would be a similar size to the aperature of a 50mm lens at f22. A photo at that opening, even of a close object would have considerably more depth of field than I perceive that I have.

    Dave
     
  11. DocFrankenstein

    DocFrankenstein Clinically Insane?

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    My eye in a relatively bright room has a diameter of 4mm (just checked in the mirror)

    50/x=4
    x~12

    50mm f/12

    or...

    35mm at f/8

    or...

    24 at f/5.6
     
  12. jadin

    jadin The Mad Hatter

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    Television is roughly 30 frames per second, or 1/30th of a second per frame. Anything lower and video won't be fluid. Video games also try to maintain at least 30 fps, ideal 60 fps. IMO the eye needs at least 30 fps, but is probably closer to 60.

    Also, Hertz, I don't think you give the eye enough credit, for starters how fast an eye focuses. It's so fast it doesn't need a large DoF, no matter what you look at it's in focus. Also it serves our purposes. Take a bird of prey's eye, it can see miles away things as small as a mouse roaming a field. Human's don't need to hunt like that, so our eyes aren't as keen. It was designed with what we needed to see... (cut short due to time)
     

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