Re: [pinhole-discussion] Human eye
Steve Bell wrote: > a little fact that may help: > > when motion pictures/films were first being made, they were > projected at one frame every 30th of a second. this was the slowest > the pictures could move without the human eye detecting that it > wasn't one, but many frames. so my conclusion is that the slowest > 'shutter speed' of the human eye is 1/30 sec. i'm sure that we have > faster 'speeds' built in there somewhere. I'm fairly sure that currently 35mm motion pictures are shot at 24 frames per second. And either 8mm or Super8 is shot at 18 frames per second. If I recall correctly film shot at 24fps is projected in such a way that each frame is shown twice at effectively 48fps. NTSC video is about 30 frames per second, and each frame is two fields (60 fields per second). PAL video is 25 frames per second. I don't know if PAL uses fields. There have been other (faster) frame rates used by various systems, but they tend to lose out to the double whamy of needing special projectors and using more film. -- Brian Reynolds | "But in the new approach, as you know, reyno...@panix.com | the important thing is to understand http://www.panix.com/~reynolds/ | what you're doing rather than to get | the right answer." -- Tom Lehrer
Re: [pinhole-discussion] Human eye
George I don't often have anything new or original to contribute to the discussion (and after this post the consensus will probably be 'just as well') but I can confirm that "pinpoint" pupils (eg from narcotic analgesia) are commonly about one millimetre in diameter, average pupil size is 2-3 mm (indoor lighting) but I have only seen 8mm pupils (fixed & dilated) in the deceased. Ray
Re: [pinhole-discussion] #80 drill bit
Hi Traci My name is Ray, from Oz the land Downunder. I lurk on this list but rarely contribute (there are already many informed voices providing advice and assistance). Regarding your comment .. ..."Or are you sticking this in an eraser like the "old fashion way"? I find that an X-Acto (or similar) hobby knife makes an excellent needle & drill-bit holding tool - see images on my website's camera project page: http://www.pinholephotography.com.au/Project/project.html
Re: [pinhole-discussion] Human eye
a little fact that may help: when motion pictures/films were first being made, they were projected at one frame every 30th of a second. this was the slowest the pictures could move without the human eye detecting that it wasn't one, but many frames. so my conclusion is that the slowest 'shutter speed' of the human eye is 1/30 sec. i'm sure that we have faster 'speeds' built in there somewhere. cheers, Steve > [Original Message] > From: George L Smyth > To: > Date: 1/5/2003 11:53:02 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/ --- Steve Bell --- veracity...@earthlink.net --- "We have...become our own thought police; but instead of calling the process by which we limit our own expression of dissent and wonder 'censorship', we call it 'concern for commercial viability'." -David Mamet
[pinhole-discussion] #80 drill bit
Hi Traci I use a Dremel tool flexshaft and I have no problems with tightening it down on a #80 bit. Sometimes it takes a couple of tries to get the little guy straight, though! Rosanne > Okay, so I ran out and got a #80 drill bit to try. Are you all putting > these in your drill? > Thanks! > Traci Bunkers
Re: [pinhole-discussion] Human eye
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: To: 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" > To: > 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/ > >
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" To: 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/ >
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
Re: [pinhole-discussion] Human eye
If the human eye/mind could be translated to camera variables.. then wouldn't it be sad to be laying on ones death bed, and start to reflect on the life we lived only to find out we forgot to put film in our camera/head. think about it. - Original Message - From: "Gary Nored" To: Sent: Saturday, January 04, 2003 11:19 PM 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 > > Difficult to answer this one (though some will try) > because the human brain does so much post processing. > Neasurements of eyeball parameters such as resolution > or depth of field are largely meaningless; that is, we see > much better than eyeball specifications would indicate. > > For example, no matter what the eyeball's depth of field, > we perceive our 'depth of field' to be infinite because that > which we attend is always in focus, and the brain fills in > the rest to make it seem so. > > Our 'focal range' changes with age. Young people can > see as close as a few centimeters -- older folks may > struggle with a meter or more. > > Our 'film speed' is continuously variable -- a dark adapted > eye can detect just a few photons yet we can also > operate well on a sunny day at the beach -- this is far > more change than can be accommodated by changes in > our 'f-stop setting' (iris diameter). > > Even our 'shutter speeds' can seem extremely short > because for the most part we see even fast-moving > objects clearly and unblurred thanks to the image > processing our brains do. > > Regards, > Gary Nored > > ___ > 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/ >
