George. The brain DOES NOT take in light similar to a movie camera's film mechanism. It "sees" light as a continuous stream. It is only through mechanical processes that wheels appear to be turning backwards whilst the vehicle is moving forward.
So there! sreehC Alan ----- Original Message ----- From: "George L Smyth" <glsm...@yahoo.com> To: <pinhole-discussion@p at ???????> Sent: Monday, January 06, 2003 5:53 PM Subject: Re: [pinhole-discussion] Human eye > While light does stream in continuously, the brain takes it in similar to a > movie camera's film. This is why you may see a bicycle's tires appear to move > backwards as it goes forwards. > > Cheers - > > george > > > > --- erick...@hickorytech.net wrote: > > Another thing occurs to me. The camera analogy is also limited by the fact > > that camera shutters open and close, while light streams into the human eye > > continuously. The operative 'shutter speed" would have to be the duration of > > exposure to the rod or cone required to trigger nerve conduction. I don't > > know whether there is a trasmission period followed by a refractory period, > > which would equate to shutter speed, or not. > > ----- Original Message ----- > > From: <erick...@hickorytech.net> > > To: <pinhole-discussion@p at ???????> > > Sent: Sunday, January 05, 2003 11:30 AM > > Subject: Re: [pinhole-discussion] Human eye > > > > > > > Here is some information I have. How it applies I'm not sure. The eye is > > > only the aperture, lens and sensing apparatus. Because the eye is attached > > > to the brain it would make more sense to use a digital camera as a model > > > rather than film camera. The mind can read an image and give a response in > > > as little as 0.04 seconds- a professional pingpong players response time, > > > for instance. Nerve transmission time mind to brain can be measured by > > > measuring cortical evoked potential responses to visual stimuli. I might > > > have once know the limiting values but I don't recall them. A big name in > > > research in this area is Meichenbaum, if you want to look it up. As for > > > aperture, the lens to retina distance is roughly 25 mm. Maximum pupil > > size, > > > i.e. aperture diameter, is maybe 8 mm in an adult, so the maximum F stop > > > would be 25/8= 3.1. Minimum aperture would be about 25/2 for 'pinpoint" > > > pupils, an F stop of 12.5. I think that the eye processes light sensation > > > somewhat differently at low light levels, so "film speed" would be a > > guess. > > > Remember too that the eye and brain cannot distinguish as separate images > > > any sequence more rapid than about 14/second. That is the basis for movies > > > and television, sequences of still images projected faster than the eye > > can > > > distinguish, thus blending them into apparent continuous motion. > > > > > > I----- Original Message ----- > > > From: "George L Smyth" <glsm...@yahoo.com> > > > To: <pinhole-discussion@p at ???????> > > > Sent: Sunday, January 05, 2003 10:53 AM > > > Subject: Re: [pinhole-discussion] Human eye > > > > > > > > > > On 22 Jul 2002, at 11:16, eco...@aol.com wrote: > > > > > > > > > I know this is not strictly pinhole, but I wondered if > > > > > anyone had access to the average human eye values for the > > > > > camera variables. ie Respective - film speed, shutter speed, > > > > > aperture, focus range, depth of field etc. Thanks > > > > > Ellis > > > > > > > > > > > > When I looked into shutter speed many years ago, I came upon the > > > conclusion > > > > that the eye's shutter speed is approximately 1/100 second. You can > > > verify > > > > this by taking successive pictures of a waterfall. We all know that > > > slowing > > > > down the shutter speed to a second or more will make for silky water, > > > which is > > > > not what we see. From there, take pictures with faster and faster > > speeds > > > > (don't forget to take notes). When you get the results, compare the > > > pictures > > > > with what you see and make the decision for yourself. > > > > > > > > Cheers - > > > > > > > > george > > > > > > > > ===== > > > > Handmade Photographic Images - http://GLSmyth.com > > > > DRiP Investing - http://DRiPInvesting.org > > > > > > > > __________________________________________________ > > > > Do you Yahoo!? > > > > Yahoo! Mail Plus - Powerful. Affordable. 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