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. Sign up now. > > http://mailplus.yahoo.com > > > > _______________________________________________ > > Post to the list as PLAIN TEXT only - no HTML > > Pinhole-Discussion mailing list > > Pinhole-Discussion@p at ??????? > > unsubscribe or change your account at > > http://www.???????/discussion/ > > > > > > _______________________________________________ > Post to the list as PLAIN TEXT only - no HTML > Pinhole-Discussion mailing list > Pinhole-Discussion@p at ??????? > unsubscribe or change your account at > http://www.???????/discussion/ > >
