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01-15-2009, 03:42 PM   #1
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Interesintg (?) observation about the "field of view of the human eye"

In discussions in other threads, the subject of what the natural field of view of the human eye (or eyes) might be. 50mm on film (or 35mm on APS-C) is often quoted, but that clearly doesn't account for peripheral vision - we can all see *way* more than that. I can see more than my 18-55 set to 18 on APS-C. So the next claim is usually that 50mm represents the "non-peripheral" portion of human vision, as if there was a hard and fast line. And at some level, there does seem to be something to this, although I've always suspected it's really narrower than that if you want to talk about the "sweet spot" of human vision. Today I had an experience that confirmed this for me.

I was stopped at a traffic light behind and one lane over from a truck that had a turn signal on its driver-side external rear view mirror as well as the usual place in the rear. The light on the mirror was shaped like an arrow pointing in the direction of intended travel. I noticed the two lights were slightly out of sync. I was having trouble if they were *constantly* out of sync - that is, mirror always coming on 0.15 seconds (or whatever) before rear, or whether they were actually flashing at different rates. But I found I was having a *devil* of a time focusing on both at once. If I focused halfway between them, *both* lights felt kind of peripheral, to the point I jus couldn't judge what was going on. My eye kep darting back and forth between them, and of course, in the process of darting, it became impossible to ascertain just what their relationship actually was. Had it not been for the blinking nature of the lights, I might have been fooled into thinking I was seeing them both at once, but the blinking drove home th I was really moving back and forth.

As I looked at the truck, I realized the field of view encompassed by these lights was quite small - about the same as that of my fist held out at arm's length. I know from experience tha this is pretty much the FOV of my 100mm lens. Luckily, I had my camera on the seat next to me, with the 100 mounted. I pointed it at the truck, and sure enough, the lights were on the extreme edges of the viewfinder.

So I can't really say exactly how big the area I can *really* focus on is, but I can tell you this - the field of view is slightly (?) narrower than that of a 100mm lens on APS-C.

01-15-2009, 04:31 PM   #2
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Marc,
as far a I know the 'real' sensor of the human eye is the fovea ('yellow spot' in the middle of the retina). With it, you can read, and that's only about 6 words width. This complies with your finding of the very narrow FOV. This thing works more or less like a slow but high-res line scanner.

On the other hand, the rest of the retina ('sensor') works something like a fast but low-res sensor, giving you something like color and light changes and basic structures (enough light needed).

The actual composition of the image (yeah it's imagination after all) is done through the brain ('jpeg engine'). On occasions like you experienced, this becomes obvious.

The basketball coach taught me to exploit peripheral vision: If you want to simultaneously keep track of two or more subjects at wide angles inbetween them, you can learn to glare 'focusless' right in the middle and then learn to perceive basic alterations of those subjects on the edges. The glaring is like daydreaming, just look straight but cut out the line scanner in the middle.

Maybe something similar is involved with people who are able to use the eye in the camera's viewfinder and the other one looking straight at the subject (they say it's the standard lens that does this job best).

Best, Georg (the baller)

Last edited by georgweb; 01-15-2009 at 04:36 PM.
01-15-2009, 05:30 PM   #3
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Marc,
My understanding has been that a 50mm lenses has about the same magnification as the human eye. Although magnification and FOV are related on a camera; with the human eye, FOV is another thing altogether and varies widely between people (see Georg's note above). Some of us take the wide view, while others the narrow...

Steve

(Think that is why I prefer wide-angle to telephoto lenses...the view looks like what I see...)
01-15-2009, 05:32 PM   #4
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QuoteOriginally posted by stevebrot Quote
FOV is another thing altogether and varies widely between people. Some of us take the wide view, while others the narrow...

Steve
As does POV

Actually for whatever reason on the K20d I find the 43 to have the "right" magnification for my eye. Maybe I'm a mutant...

01-15-2009, 06:29 PM   #5
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Lensbaby photos remind me of human vision.


01-15-2009, 07:02 PM   #6
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personally ive learnt to use my peripheral vision as much as i can.... like i'd be walking around looking ahead but if there's people around me i use my peripheral vision to check up on them (like if they're about to walk into me or something)...

its a good exercise to do - you can train yourself to have better use of it and things get "easier"

and im not a baller... i just like to look at things without people realising i am... (i also have a tendency to wear sunglasses indoors and at night)
01-15-2009, 08:10 PM   #7
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Human vision is using a process called "saccades" to scan different areas of a scene that was stored in an area called superior colliculus. From there, the information is forwarded into processing centre along with other sensory information which include tactile information, smell and hearing etc. All these information are to be "interpreted" by the stored experiences from the past as well as under significant mood status of the individual.

Photography is trying to capture certain visual clues that would evoke a common feeling among the viewers. Thus viewers would share the feeling of the photographers
01-15-2009, 08:53 PM   #8
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Not to threadjack, but I also noticed the other day that the human eye (or mine, at least ) suffers from noise, particularly in low light -- stare at a white wall and relax, and you can see "shimmer" in the flat areas, just like a digital sensor. Your brain is just really good at tuning it out so you don't notice it normally.

Reid

01-15-2009, 09:27 PM   #9
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QuoteOriginally posted by stevebrot Quote
My understanding has been that a 50mm lenses has about the same magnification as the human eye.
This can be true, but it of course depends on the magnification of your viewfinder. Also, I'm not sure if this is an inherent feature of all possible 50mm lenses, or if it is somehow specific to the size and distance of the film/sensor/focus screen from the lens.

But in any case, it *has* also been claimed that 50mm reflects the field of view of human vision. For that matter, it's also been claimed that it reflects the "perspective" of human vision, but we don't need to go there again :-) I'm just making some observations about field of view.
01-15-2009, 11:52 PM   #10
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I remember reading back in school that the "focus area" at any time is only 5% of the total field of view. It's really pitiful how little we can actually focus sharply on at one time but our brain and eye movements are fast enough to make up for it decently. For example, though, if I think about it, I can't even focus sharply on the whole of the text box I'm currently writing in, only about half its width.
01-15-2009, 11:57 PM   #11
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QuoteOriginally posted by rpriedhorsky Quote
Not to threadjack, but I also noticed the other day that the human eye (or mine, at least ) suffers from noise, particularly in low light -- stare at a white wall and relax, and you can see "shimmer" in the flat areas, just like a digital sensor. Your brain is just really good at tuning it out so you don't notice it normally.

Reid
As far as I understand this comes from previous damage that the eye has sustained from looking at overly bright light sources and so forth. But as you say, the brain is generally great at filtering it out. It's much the same thing as a slight case of tinnitus in the ear; you can hear it when in a perfectly quiet environment, but otherwise it's impossible to think of.
01-16-2009, 01:16 AM   #12
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QuoteOriginally posted by roentarre Quote
Human vision is using a process called "saccades" to scan different areas of a scene that was stored in an area called superior colliculus. From there, the information is forwarded into processing centre along with other sensory information which include tactile information, smell and hearing etc. All these information are to be "interpreted" by the stored experiences from the past as well as under significant mood status of the individual.

Photography is trying to capture certain visual clues that would evoke a common feeling among the viewers. Thus viewers would share the feeling of the photographers
James, is there a medical equivalent term for bokeh?
01-16-2009, 01:20 AM   #13
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QuoteOriginally posted by Damn Brit Quote
James, is there a medical equivalent term for bokeh?
Mind altering drugs perhaps????


Damn James ... I didn't realise about that info though.
01-16-2009, 03:27 AM   #14
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I wonder if the most important "optical" nerve is the brain taken as a whole.

For years ornithologist have marveled at a raptors ability to "see" a mouse underneath the leaf litter a half mile away.

It turns out, to some extent, that they were wrong. A Hawk does not so much "see" the mouse but rather the hawk's brain is highly developed to notice (rather than see) any difference in it's FOV as it scans a FOV. First it scans, let's say, from right to left and then stores that image in it's brain and then scans in reverse from left to right. Any difference in the two scans alerts the bird that something important has happened in it's FOV - food. This is pretty sophisticated stuff - rather like a CIA agent comparing two different aerial photos of the same area taken at two different times.

I guess my point in all this is that I think what we think we "see" or don't "see" is not only determined by optics alone but also by our brains. As a result of millions of years of evolution our brains have determined what is most important for us to notice and pay attention to and also what to ignore.

I'd even go further and wonder if humans, being the complex creatures we are, tend to "see" and not "see" different things based on the peculiar culture we grew up in.

Last edited by wildman; 01-16-2009 at 03:37 AM.
01-16-2009, 07:39 AM   #15
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QuoteQuote:
wildman said:
I'd even go further and wonder if humans, being the complex creatures we are, tend to "see" and not "see" different things based on the peculiar culture we grew up in.
Absolutely, a story comes to mind of a tribe from the Amazon jungle. They are said to distinguish and name 40 different colors of green.

Best, Georg (the other)
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