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Old 02-06-2005, 05:06 PM
InvidiousCourgette InvidiousCourgette is offline
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What shape is the human field of vision?

Over dinner tonight I was discussing with a friend the aspect ratios of various film formats. Anyway we were wondering if the common film formats have any relationship with our field of vision. When I stand up cose to something it seems I can see things that are futher apart horizontally than vertically. I am not sure about things that are further away than a few feet though. So how about it, can we say that our field of vision is basically oval or what? Any studies that have quantified it?
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Old 02-06-2005, 05:41 PM
Qadgop the Mercotan Qadgop the Mercotan is online now
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Our visual fields are two circles which overlap. Each circle represents the peripheral vision of one eye which is focusing at an object about the the center of the circle. A visual field test will demonstrate where the blind spot is in the circle, but otherwise everything within the circle should be seen by the healthy eye.

Google "visual field" and you'll find plenty of sites with graphs, etc. Just be prepared to deal with terms like "Homonymous quadrinopia", "Incongruous homonymous hemianopia", "Junctional scotoma" and the like!
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Old 02-06-2005, 06:52 PM
InvidiousCourgette InvidiousCourgette is offline
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Thanks Qadgop, that makes sense. I did some googling and I am still unsure about this, however. If I am in a cinema with a screen say 20' away from me, do my two eyes focus on two different circles, say, 5' away from each other?
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Old 02-06-2005, 07:52 PM
wolf_meister wolf_meister is offline
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Maybe it is a little soon , but sooner or later, someone will want to know about calculating angular size:
www.1728.com/angsize.htm
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Old 02-06-2005, 09:38 PM
Richard Pearse Richard Pearse is offline
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Quote:
Originally Posted by InvidiousCourgette
Thanks Qadgop, that makes sense. I did some googling and I am still unsure about this, however. If I am in a cinema with a screen say 20' away from me, do my two eyes focus on two different circles, say, 5' away from each other?
Your eyes focus on the same spot as each other (otherwise you'd see double images) but there is an area that each eye sees, that the other eye doesn't, and that the brain pretty much ignores unless you mentally focus on it. E.g., I can actually see both sides of my nose at all times, but unless I concentrate on it it dissappears into the blur of unimportant image.

To me, my field of view seems essentially circular, though there is very little to look at vertically so I take a lot more notice of objects arranged horizontally, this maybe why cinematic formats work well, there is very little point showing more sky, but you can achieve a lot by showing more horizon.
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Old 02-06-2005, 10:28 PM
commasense commasense is offline
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You can determine the approximate shape of your visual field by looking straight ahead, and holding a hand out to each side and noticing where you can no longer see them. Do the same for above and below, and you'll see that your peripheral vision probably extends to about 180 degrees (or a little less) left and right, and about 100 degrees up and down. Your brow, nose, and cheeks narrow the vertical angle.

So your visual field has a ratio of about 1 to 1.8.

Interestingly, and not entirely coincidentally, ordinary films and wide-screen TVs have a ratio of 1.78 (16:9).

"Scope" 35mm films are 2.35, and some of the special formats (Cinerama, Todd-AO, etc.) went as wide as 2.76. (See here for more information about film formats.)
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Old 02-06-2005, 11:25 PM
Walloon Walloon is offline
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Nitpick: As the link you supplied says, Todd-AO had an aspect ratio of 2.20:1, which was narrower than CinemaScope, not wider. However, because it used a 65mm negative, it had a much higher resolution than CinemaScope, which used a 35mm negative.
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