Camera vs the Human Eye. And do digital sensors lose effectiveness after some time?

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Why can’t I just point my camera at what I’m seeing and record that?” If you are looking for the answer you can find it here at Cambridgeincolor.com. It’s really one of the best articles I have read recently. There are a couple of very interesting facts:

1) Angle of view

Although the human eye has a focal length of approximately 22 mm, this is misleading because (i) the back of our eyes are curved, (ii) the periphery of our visual field contains progressively less detail than the center, and (iii) the scene we perceive is the combined result of both eyes.” and “Our central angle of view — around 40-60° — is what most impacts our perception. Subjectively, this would correspond with the angle over which you could recall objects without moving your eyes. Incidentally, this is close to a 50 mm “normal” focal length lens on a full frame camera

2) Resolution and detail

I guess most of us thought our eye would have more “Megapixels” than a camera. Surprisingly the answer is NO! Cambridgeincolor says: “A single glance by our eyes is therefore only capable of perceiving detail comparable to a 5-15 megapixel camera (depending on one’s eyesight). However, our mind doesn’t actually remember images pixel by pixel; it instead records memorable textures, color and contrast on an image by image basis.”

3) Sensivity and Dynamic Range

Dynamic range* is one area where the eye is often seen as having a huge advantage. If we were to consider situations where our pupil opens and closes for different brightness regions, then yes, our eyes far surpass the capabilities of a single camera image (and can have a range exceeding 24 f-stops). However, in such situations our eye is dynamically adjusting like a video camera, so this arguably isn’t a fair comparison.

Conclusion:Overall, most of the advantages of our visual system stem from the fact that our mind is able to intelligently interpret the information from our eyes, whereas with a camera, all we have is the raw image. Even so, current digital cameras fare surprisingly well, and surpass our own eyes for several visual capabilities. The real winner is the photographer who is able to intelligently assemble multiple camera images — thereby surpassing even our own mental image.

—-

And there is another interesting article at Quesabesde (Click here to read the google english translation) The question is: “Do digital sensors lose effectiveness after some time?” The answer is No!….But not a 100% No :)

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  • cL

    Rather strange article, though I wanted to say misleading, but I don’t think that’s the right word…. Eyes do have a strangely high dynamic range, that’s why no camera can surpass that any time soon, because we also have brains that control the eyes (which is more like the lens). That part I agree. Compare a digital format using megapixel to compare eyes is not effective because eyes are analog. That is, we see full spectrum, not interpolates them into 0’s and 1’s. Though rods and cones of our eyes is the bases of sensor design. Eyes have no megapixels, because we see the whole thing, not parts of the thing is what I am saying. Even if you use ProRGB color space, you’re not going to see the same degree of colors your eyes can interpret. A digital camera has limited AI to interpret things. Even then, it interpret things “objectively” whereas our eyes sees things “subjectively.” And that is a good thing in this regard. Our other senses also affect our vision. Cameras have no emotion, so they can only capture what it is.

  • So my brain is the best RAW converter ever,
    but seriously i don’t think that photographers should be trying to mimic eyesight with cameras, as this is impossible and wouldnt be artistic

    • Atle

      Why wouldn’t it be artistic? Isn’t that just a random limit? Isn’t that just like saying that photos can’t be artistic, only paintins can? I am sure one can be artistic with a camera with more eye-like performance too.

    • cL

      I think art is in the eye of the beholder. There are many types of arts and different people who appreciate each style.

  • What is the aperture of our eyes? ƒ/1.0?

    • I imagine it varies depend on how much light is available ,our eyes dilate in low light and we squint in bright sunshine…

      • I am asking this question because I read stories of very low ƒ-number lenses which are supposed to be “brighter than the naked eye.” But when do we consider a lens to be brighter than the eye?

    • WyldRage

      Google and wikipedia are your friends:

      “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.”

      http://en.wikipedia.org/wiki/F-number#Human_eye

      • cL

        This kind of approximation is sketchy at best. f/number is focal length divided by diameter of the opening…. So that means the distance between cornea and optic disc portion of retina divided by the diameter of pupil. So if your eye size is different, then the number won’t be exact. If your pupil response to light differently than another person around you, then the number would be different. If your optic region is different size, then the DoF would be different. If your rods and cones have different density, then your light sensitivity would be different… If you have more rods than cones, than your perception of color would be different, and let’s not even talk about the optic region of the brain, which also affects how you see things….

        The info proposed is just a theory…. Most parts of human bodies, we still don’t know how they work (we know what they do but we don’t know exactly how they do it, this is especially true for brain and liver).

        Even if you found out the exact f/number of your eyes (which can be done, just simple math), but we won’t know how that interprets into light sensitivity, DR range or DoF.

        Yes, I’ve read human eyes’ f/number is about f/8. But number alone doesn’t mean much, you see. f/8 on a FF is very different from f/8 in a P&S camera, for example.

  • I prefer the cameras dynamic range of 10-12 ev it’s more interesting than the human eye artistically wise, just my thoughts…

    “it instead records memorable textures,color and contrast on an image”
    you can “replicate” this effect with the camera’s tools like spot metering, white balance, focus point etc

    I also find the four thirds 25mm (50mm full frame equiv.)gives me practically the same view on what I’m concentrating/zoning in on visually of a scene in front of me..

    • Mr. Reeee

      Interesting.
      Recently, when I was trying to decide whether to get a 35mm or 40mm lens, I was experimenting with my 14-140mm trying to figure out what was 1:1 for my eyes.

      With one eye looking through the EVF and the other just looking, then trying to overlap the images for scale, my eyes see 35mm (70mm equiv) is just about 1:1 for me.

      That was it, I bought the 35mm!

      • random guy

        Then you are matching viewfinder magnification, not “focal equivalence”

  • Chris

    I think Micro 4/3 will be the future of cameras and getting closer to 1:1 of the human eye. There is a 50 Mega pixel camera, but it costs £20,000 and its used to take pictures of models.

    Its ironic really because you can buy a £40 old medium format camera that was made in the 1950s that can be used too take photos, then the 35mm frame shots scanned too 5 times the resolustion of cameras of today. The result is a better quality photo with more depth of detail. Thats evolustion for you :-)

    • SteveO

      Which is exactly what kept me on the sidelines of digital for quite some time. Finally it was convenience (instant results, no film and development costs, no development delay with uncertain results), not image quality, that carried the day for digital.

    • Camaman

      Isn’t that dependent on viewfinder magnification to?
      I mean the lens should “appear” different if viewfinder magnification is x0,7, x0,95, or x1,15, no?

      • cL

        1.0 magnification means life size. It has something to do with the lens, so you’re right about that.

  • Anonymous

    >”The real winner is the photographer who is able to intelligently assemble multiple camera images — thereby surpassing even our own mental image.”

    No, it´s not about that. The painter is also limited and has to choose the right from reality. But if you take it technically assembling images e.g. with various exposition won´t give you tonal resolution and range of human eye in enviroment limited by color depth and tonal range of the monitor or printer…

  • frankv

    As to comparison of the focal lenght to your field of vision I find that when using the 20/1.7 I always have to take a step back from where I am standing looking at things before I can grab that in a picture.

    So I think my eyes when looking at things while walking around normally work like a lens with a focal length at full frame of about 35mm.

    I have always liked wide angles and normal lenses the best and do not like anything over 135mm full frame.

    • cL

      That’s about the field of view of my eyes too, it’s about 35mm. 50mm is referring to the field of view that is most sharply focused. Our eyes aren’t sharp edge-to-edge. Neither are our eyes have distinct bokeh area. Everything we see are always “relatively” in focus. The bokeh in the photo is a “simulation” of out-of-focus area. So get back to the “theory” that human eyes are about f/8, which I can believe it (just not the absolute number), further away from f/8, the less realistic the photo becomes. And when you use 4/3 sensor, that probably means you want it to be as close to f/5.6 as possible, if what you want is realism. Our eyes hits “infinite” focus rather early, so most of the stuff will be in sharp focus unless you put your subject really close to your eyes, so that means macro photography where you point your subject like 1 inch from your subject and shoot at f/2 would look more artistic than realistic.

  • stopkidding

    what the eye relies on post processing and not SOOC? (Straight out of the Cornea). This is so disappointing! :-D

  • MP Burke

    This is a useful link as it provides a nice short explanation of why we may perceive that cameras have a low dynamic range compared to our eyesight. That site also contains a useful depth of field calculator which can take account of print size and viewing distance, rather than using arbitrary values for the circle of confusion.

  • Inge-M.

    Human eye focal lenght ca. 22mm and angle of view 40-60, so very close to M43 ;-)

  • Scott

    What makes images look artistic or pleasing is to see them from a different percpective than what we see with our own eyes. To me a point and shoot is closer to the human eye.

  • Jim

    Well I think the real achivement of the eye is being able to provide a short exposure (arguably 30fps ish… so 1/30 sec exposuere) in near pich dark and still give a good image… no noise! so what is that a very clean ISO 50k?… better than the D3s!

  • Hogan

    I disagree that 50mm is the closest focal length to the eye.
    Time and again I’ve tried to see the exact size and shapes and 50mm is not it. The picture is much smaller in the 50mm than what I see with my eyes.
    It’s much more closer to 70mm.

  • Per

    The human “camera” has many advantages:
    -The lens is rotating
    -Re-focus in no-time
    -“Processor” that constantly recalculates the capture
    -Based on information stored in the “hard disc” evaluates the content of the capture – including filling in gaps.
    – includes information from other senses

    The photo is just a “save as frozen” 1/125 sec capture from an ongoing scene. It is impossible to see what was outside the frame as well as before and afterwards.
    The key to a really good photograph bridge the gap between photo and human perception by get the viewer’s imagination understand the content in the same way as photographer percieved it before, during and after capture.
    (= do not bother so much if Olympus i better or worse than Panasonic, not speaking of the non-m4/3 enemies! Welcome and embrace technical development, but understand that it has little to do with your success as photographer.)

  • BCK

    Our eyes DO in fact have a higher dynamic range than any consumer camera, but it comes at a cost.

    The human eye has poor acknowledgment of fine gradation steps.

    Think of it as it can only see the difference in a shadows different shades that are separated by at lest 2f stops (-not correct, just an example)

    Otherwise, in our brain the shades will blend into the same colour if they are not separated enough.

  • random guy

    This grossly overlook an important factor. Our eyes do not only do HDR with different apertures. The sensor itself is logarithmic, unlike silicon which is linear. This means that the dynamic range is much larger by itself, and becomes huge when doing “multiple exposure”.
    See here: http://en.wikipedia.org/wiki/Stevens_power_law

    The “drawback” is that it’s less sensitive to small nuance of brightness.

    Then, it doesn’t mention rods, which are super-high sensitive, although very poor quality (besides B/N). Still humans can walk in the “dark” where no camera can take pictures (in visible light, but often there’s enough IR for IR imaging)

  • Kralin

    Actually you are missing a big plus of the human eye. It can adapt dynamically to light even for small region of the retina. Meaning that you can have small sensibility for a part of the retina looking at brigth image, and the remaining part will adapt to what it is “seeing” at the moment. That’s why we hab a much more higher live dynamic range. And that’s why we like HDR images.

  • safaridon

    If true my eye can only resolve anywhere between 5mp and 15mp then it seems quite logical unless one is going to crop significantly that there is no need to go beyond say 10mp-15mp and to limit cropping to not less than 5mp size for good IQ?

    As a wildlife photographer I see many people using shorter normal or effective 135mm lens coming away very disappointed as they try to identify the speck of an animal in their pictures to share with others. Like Reece I come away from the perspective that the size of picture my eye sees is greater than 50mm not less as others have stated. I think that all depends on the distance you are from the object?

    I am not being very scientific here but this is my rational attempt at explanation. First what our eye sees is almost a 180 degree panarama and and an overall scene much larger than projected in our typical small 8×10 photos so more like 1:1 size or 40″x 25″ and not 10″x 8″ or smaller most print due to most common printer sizes. So to get the same animal size in our 10″x8″ picture a reduction of -4x as we see with with our eyes we have to use a 50mm x 4 = 200mm effective lens size for shooting wildlife at a distance! And if we want something to look larger than that speck of a cheetah at 150 yards in the distance we really need an effective focal length of say 400 to 600mm for our telephoto range. This is why for years with SLRs a fast f2.8 200mm tele lens was the norm and now with digital 400mm effective reach is considered a minimum for many as that magnifies what our eye sees by only a factor of 2x for an 8″x10″ print? Please note this perception changes in the opposite direction as we have to go wider instead for close ups.

    I just got back from a 6 day photographic safari in Tanzania’s national parks and found my FF 70-300mm inoperable so had to settle for my 55-200 lens (effective 70-300mm focal length) instead but the 8 GB of photos turned out sharper in my eyes except for some distant cheetah ones because of better depth of field. I took enough pictures that I can even show 4 GB worth 850 pictures as a quick preview video show in less than 4 minutes just holding the view button down on my DSLR. Yes I also took video with a camcorder but hard to do both at the same time. I got much better shots of wildlife just catching the occassion rather than fumbling around trying to change settings on my DSLR and missing the shots of a lifetime.

    Please give your comments, Am I all wet in the above analogy?

    • Jim

      WELL I GOT 20 20 VISION AND MY EP1 KIT ZOOM AT 42MM WILL PICK UP DETAILS MY EYE CANT – … NOT BY MILES BUT IT DOES BEAT MY EYE… SO 12MPIX AT 84MM EFFECTIVE IS BETTER THAN EYE… FOV IS WAY WIDER WITH EYE – MORE LIKE 20MM EQU BUT WITH A 40-50MPIX QUALITY…

      OBVIOUSLY THE EYE SCANS THE VISION AREA SO YOU NEVER SEE THE WHOLE IMAGE AT ONE MOMENT – ITS THE BRAIN THAT “STICHES” THE SCANNIING…

      EXCUSE CAPS….

  • wayne

    The center part of vision is a small spot that has 2400dpi, 1200 in color. The eye flicks around scanning the scene. It diminishes towards the outside where it picks up speed to over 500fps for looking at Sun bright flashes in pitch dark. While the normal angle of view might be most memorable, there is second zone outside that before the third zone where you have to keep turning your head to look to see what it was. When you put all these factors together, our cameras have a long long way to go, we could be talking about 40 thousand pixels accross. Using today’s regular consumer technology and format sizes we could be talking about very noisy images with less than 8 stops of latitude.

    Omron developed a car camera sensor with 27 stops of latitude several years ago, with low light ability and superior color.

  • Jay S

    What a load of crock !! “5-15 megapixels”?? I am looking around my room right now and I can see details that my 14-megapixel camera couldn’t come within whispering distance. True, the central area of focus for the human eye is much smaller than the camera. But the resolution of the human eye is indeed limitless – depending of course, on the health of the viewing eye.

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