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Photo Forum / Film Photography / 35 mm / November 2006Is f/ 1,000,000 a Possible Aperture?
Diffraction limitation and exposure time considerations aside. Can a photon(s) squeeze through something this tight and still for some kind of image? And to open it up to, let's say, to f/5000, would one take ExLax or an aspirin? Going to the opposite extreme -- can an f/0 "lens" exist (other than in the imagination or in the Twilight Zone?... P.S. - What's the bokeh like on an f/1,000,000 (?pinhole?) "lens" and would you bracket exposures using this "lens" in centuries or light years? Dark years? Dark Milleniums? > Diffraction limitation and exposure time considerations aside. Can a > photon(s) squeeze through something this tight and still for some kind [quoted text clipped - 7 lines] > would you bracket exposures using this "lens" in centuries or light > years? Dark years? Dark Milleniums? First, the size of the aperture depends on the focal length of the lens for a given f/stop. For a 10,000mm lens, f/1,000,000 would be 1/100mm, plenty big enough for several photons. Second, the exposure time would depend on the sensitivity of the sensor. In your imaginary world you must have a sensor with an ISO in the 100,000 range with an infinitely linear response curve. f/16 @ 1/100,000th (sunny 16 rule) becomes 11.9 hours @ f/1,000,000 (with tri-x the exposure would be about 124 days not accounting for reciprocity failure) The f/0 lens is another matter, dividing by zero being undefined and all.... I apologize in advance for any arithmetic errors.  SignatureTom Thackrey www.creative-light.com tom (at) creative (dash) light (dot) com do NOT send email to jamesbutler@willglen.net (it's reserved for spammers) BIG SNIP OF INCREDIBLY DETAILED REPLY > I apologize in advance for any arithmetic errors. > [quoted text clipped - 3 lines] > tom (at) creative (dash) light (dot) com > do NOT send email to jamesbutler@willglen.net (it's reserved for spammers) No need to apologize. And thanks. I am amazed that you went through so much trouble to do all the math in the first place! I won't ask you about neutral density filters or exposure compensation factors for bellows extension factors and exposure times for f/1,000,000 close ups... ;-) > Second, the exposure time would depend on the sensitivity of the > sensor. [quoted text clipped - 4 lines] > (with tri-x the exposure would be about 124 days not accounting for > reciprocity failure) Actually, you're applying the change for the miniscule f-stop twice here. You can keep the film/sensor ISO at 100 or whatever you like, but then apply the f-stop to that figure. Sunny 16 is simply a shutter speed of 1/ISO, and all you have to do is expand the f16 to f1,000,000. > I apologize in advance for any arithmetic errors. We'll wait and see who nails the ones in my post ;-) - Al. SignatureTo reply, insert dash in address to match domain below Online photo gallery at www.wading-in.net > Diffraction limitation and exposure time considerations aside. Can a > photon(s) squeeze through something this tight and still for some kind [quoted text clipped - 7 lines] > would you bracket exposures using this "lens" in centuries or light > years? Dark years? Dark Milleniums? F stops are just a ratio of two lens dimensions....Yes, an aperture of a million can exist, but f/0 cannot...... > > Diffraction limitation and exposure time considerations aside. Can a > > photon(s) squeeze through something this tight and still for some kind [quoted text clipped - 10 lines] > F stops are just a ratio of two lens dimensions....Yes, an aperture of a > million can exist, but f/0 cannot...... Not even if I hold up my hand in front of the lens to block out all the light? ;-) >> > Diffraction limitation and exposure time considerations aside. Can a >> > photon(s) squeeze through something this tight and still for some kind [quoted text clipped - 13 lines] > Not even if I hold up my hand in front of the lens to block out all the > light? ;-) No, this would (theoretically) have the opposite effect, and give you an infinitely large f stop.....Remember, the larger the f stop, the slower the lens.....No light at all is a very slow lens...... > Diffraction limitation and exposure time considerations aside. Can a > photon(s) squeeze through something this tight and still for some kind [quoted text clipped - 7 lines] > would you bracket exposures using this "lens" in centuries or light > years? Dark years? Dark Milleniums? Since f-stop is a relation to focal length over aperture, theoretically, extremely small f-stops are possible. An f-stop of 2.8 on a 50mm lens is actually an opening that is 1/2.8 of the focal length, or 17.85mm. An f-stop of 1,000,000 (for a 50mm lens) is .00005mm, or 50,000 nanometers. Visible light runs between 400 and 700 nanometers, so even given the thickness of the aperture material, you should be able to let plenty of photons through without wave interference. You're actually indicating an opening of a fine human hair (but not a coarse one). Then you come to the problem that you're focusing the light through a lens. Given that different wavelengths (colors) of light get bent by differing amounts when passing through the same material, methinks you stand the chance of registering a 'focused' image in only one color, and that's only if you have a precise alignment of the teeny aperture within the nodal point of the lens for any given wavelength. Exposure time? About sixteen stops down from Sunny 16. With ISO 100 film, that's 655 seconds. But considering that you may only be getting a portion of the light focused through the lens, you may need a lot longer than that. Get rid of the lens and simply use your 50,000n opening as a pinhole lens, and now you're talking about f920,000. Hey, that's only 575 seconds, for them action shots! Your glacier photos will no longer be blurry... (These times, of course, say nothing about reciprocity failure, which will slam the hell out of them) I have heard of people creating ultra-fine pinholes with an electrical charge grounded into a thin brass sheet (zap!), so 50,000n may even be possible. And without the lens, you should be free of color problems. Second question: Is f0 possible? Well, no, not in the conventional sense that it is a measurement based on focal length. You can probably approximate it by hauling your film out of the cassette in bright daylight, though. So, what's the bokeh like on an f1,000,000 pinhole? You silly, there *is* no bokeh - pinholes work by making everything in focus. Given, however, that most pinholes are not perfect, the end effect is usually a certain level of softness or diffraction, and that differs for every pinhole. You can call that bokeh if you like. See http://ca.geocities.com/penate@rogers.com/pinsize.htm and http://www.ringsurf.com/netring?ring=pinholephotography;id=1;action=list for sources of this info, and bear in mind I sucked at math, so decimals may have wandered out of place. The f-stop of the pinhole (used alone) was based on a rough measurement from the inside edge of the body cap for Canon EF cameras - I got a 46mm focal length. - Al. SignatureTo reply, insert dash in address to match domain below Online photo gallery at www.wading-in.net >> Diffraction limitation and exposure time considerations aside. Can a >> photon(s) squeeze through something this tight and still for some kind [quoted text clipped - 30 lines] > portion of the light focused through the lens, you may need a lot longer > than that. Yeah....When you get down to quantum calculations, you are talking about probabilities....What is the probability that your photon will happen to hit the hole, and get through to your sensing plane? ....:^) > >> Diffraction limitation and exposure time considerations aside. Can a > >> photon(s) squeeze through something this tight and still for some kind [quoted text clipped - 34 lines] > probabilities....What is the probability that your photon will happen to hit > the hole, and get through to your sensing plane? ....:^) ...It depends on how good your golf swing is... ;-) For a 50mm lens f/1,000,000 is 50 x 10^-3 x 10^-6 = 50 x 10^-9 = 50 nanometers Light will get through - semiconductor manufacturers are pushing light through 35nm apertures but there it is a contact printing process and there is a lot funny business going on. All you will get out of this is diffraction - well not even diffraction - more like fog. Getting any exposure on the film is another matter what with reciprocity failure. The quantum realm aside, you are 40 stops below f1.0 - light is attenuated by a factor of ~10^-12. Sunny 16 on ASA 125 film will be 2^25 seconds or about 1 year at f/1,000,000. SignatureNicholas O. Lindan, Cleveland, Ohio Darkroom Automation: F-Stop Timers, Enlarging Meters http://www.nolindan.com/da/index.htm n o lindan at ix dot netcom dot com "Nicholas O. Lindan" <see@sig.com> wrote in news:LXG5h.6124$ig4.4796 @newsread2.news.pas.earthlink.net: > For a 50mm lens f/1,000,000 is 50 x 10^-3 x 10^-6 = > 50 x 10^-9 = 50 nanometers I'm missing something here (and it could be me - you do a lot more in this realm than I do). But where did the 10^-3 part come from? I got f/1=50mm, f/10=5mm, f/100=0.5mm, and so on to f/1,000,000= 0.00005mm, which should be 50 microns or 50,000 nanometers. > Light will get through - semiconductor manufacturers > are pushing light through 35nm apertures but there it [quoted text clipped - 9 lines] > on ASA 125 film will be 2^25 seconds or about 1 year > at f/1,000,000. The rest I get, especially when you're talking aperture openings smaller than the wavelengths of the light you're trying to admit. Your aperture material also has to be thinner than the wavelengths, otherwise you're just scattering it in the "tube" and/or diffraction affects all photons passing through. - Al. SignatureTo reply, insert dash in address to match domain below Online photo gallery at www.wading-in.net "Al Denelsbeck" <newsgroup@wadingin.net> wrote in message > > For a 50mm lens f/1,000,000 is 50 x 10^-3 x 10^-6 = > > 50 x 10^-9 = 50 nanometers > I'm missing something here (and it could be me - you do a lot more > in this realm than I do). But where did the 10^-3 part come from? 50mm = 50 millimeters = 50 1/1000's of a meter = 50 x 10^-3 meters 1/1,000,000 of 50 x 10^-3 meters = 50 x 10^-9 meters = 50 billionths of a meter = 50 nanometers SignatureNicholas O. Lindan, Cleveland, Ohio Darkroom Automation: F-Stop Timers, Enlarging Meters http://www.nolindan.com/da/index.htm n o lindan at ix dot netcom dot com "Nicholas O. Lindan" <see@sig.com> wrote in news:VoI5h.5897$L6.2181 @newsread3.news.pas.earthlink.net: > "Al Denelsbeck" <newsgroup@wadingin.net> wrote in message > [quoted text clipped - 10 lines] > = 50 billionths of a meter > = 50 nanometers Ah, gotcha! Took me a few, but I eventually realized I started with millimeters, not meters. You're right. Shift decimal three to the right. So, short answer, "No." - Al. SignatureTo reply, insert dash in address to match domain below Online photo gallery at www.wading-in.net > For a 50mm lens f/1,000,000 is 50 x 10^-3 x 10^-6 = > 50 x 10^-9 = 50 nanometers [quoted text clipped - 18 lines] > http://www.nolindan.com/da/index.htm > n o lindan at ix dot netcom dot com Thanks for the math check, Nicholas. BIG SNIPS > Get rid of the lens and simply use your 50,000n opening as a pinhole > lens, and now you're talking about f920,000. Hey, that's only 575 seconds, > for them action shots! Your glacier photos will no longer be blurry... LOL, thanks I needed that laugh :-) > (These times, of course, say nothing about reciprocity failure, which > will slam the hell out of them) [quoted text clipped - 8 lines] > approximate it by hauling your film out of the cassette in bright daylight, > though. Hahaahahahahahahhhahaahahhhaahhaahahhaa.... Now I'm blowing photons out my nose... > So, what's the bokeh like on an f1,000,000 pinhole? You silly, there > *is* no bokeh - pinholes work by making everything in focus. [quoted text clipped - 15 lines] > To reply, insert dash in address to match domain below > Online photo gallery at www.wading-in.net Thanks for the link... and the explanation :-) > Diffraction limitation and exposure time considerations aside. Can a > photon(s) squeeze through something this tight and still for some kind [quoted text clipped - 7 lines] > would you bracket exposures using this "lens" in centuries or light > years? Dark years? Dark Milleniums? To get any kind of image you need at aperture of at least a few wavelengths. So lets say you want an aperture of 0.005mm, at f/1,000,000 you would need a FL of at least 5,000,mm. And the image you would get would be maybe 100 pixels in resolution and would require film or a sensor that was a few meters on a side. Now an electron mircoscope and run at f/1,000,000 because the wavelength of an electron is much smaller. Or you could use hard x-rays with shorter wavelengths. Scott [SNIP] > Now an electron mircoscope and run at f/1,000,000 because the > wavelength of an electron is much smaller. Or you could use hard > x-rays with shorter wavelengths. But then what do you make your aperture out of? Given that it needs to be thin, you'll have as many X-rays passing right through it as go through the hole in it. :-( Peter > [SNIP] > > [quoted text clipped - 9 lines] > > Peter You use a mirror at a glancing angle. Scott > > [SNIP] > > > [quoted text clipped - 11 lines] > > You use a mirror at a glancing angle. Ahh, that makes sense. What will act as a mirror for hard X-rays? (I'm thinking not the same things as we use as a mirror for light.) Peter >> > [SNIP] >> > > [quoted text clipped - 14 lines] > Ahh, that makes sense. What will act as a mirror for hard X-rays? (I'm > thinking not the same things as we use as a mirror for light.) Crystals can be used to bend/reflect x-rays.......I see the SLAC lab in Menlo Park, California is building an x-ray laser source.....Coherent x-rays....What a concept! > >> > [SNIP] > >> > > [quoted text clipped - 18 lines] > Menlo Park, California is building an x-ray laser source.....Coherent > x-rays....What a concept! Don't tell McDonalds, they already make their French Fries fast enough! :-) OK, here's a stupid thought, if X-ray lasers are possible then how about radio waves or micro waves (someone is about to tell me they are the same thing - I am not that hep on all of the subtleties of the electromagnetic spectrum...) lasers? Pulse it fast enough and it could be used for communications or frying birds in mid-flight befor they could fly into the openings of jet engines... > > >> > [SNIP] > > >> > > [quoted text clipped - 28 lines] > be used for communications or frying birds in mid-flight befor they > could fly into the openings of jet engines... ...Speaking of lasers... do holograms have bokeh or is that sort of negated by the fact that all of the light rays used to take them with are parallel, don't require lenses that could make blur circles, and therefore don't form blur circles... unless there is some kind of intermediary kind of light between lens focused light and the perfectly collimated (if that's the right term) laser light that you could still make a hologram with... Its been years but I don't remember any selective focus effects with the holograms I saw in college, the bokeh was mostly in the fuzziness/"fuzzy logic" of my mind ;-) >> > >> > [SNIP] >> > >> > > [quoted text clipped - 39 lines] > selective focus effects with the holograms I saw in college, the bokeh > was mostly in the fuzziness/"fuzzy logic" of my mind ;-) Yes.....I've never seen a hologram that had anything in it out of focus.....But then, I haven't seen a lot of these things....They were a big thing about 30 years ago, but they never lived up to their promise, and they sort of. "died on the vine"....... > ...Speaking of lasers... do holograms have bokeh or is that sort of > negated by the fact that all of the light rays used to take them with [quoted text clipped - 5 lines] > selective focus effects with the holograms I saw in college, the bokeh > was mostly in the fuzziness/"fuzzy logic" of my mind ;-) A hologram recreates the wave front of light and so when you are looking at you it looks just as if the object was there. I use to shoot a lot of holograms and one of my tricks I would play on people would be to leave the object that the hologram was taken of in place and have people view the holograms. They would claim they could not see the hologram until I had them put their hand between the holograms and the object, and of course you can still see the object. I did vibration testing using holograms and since a hologram is not the easiest thing to put in a test report we would shoot 35mm photos of it. This is not much different then shooting a photo of the real object, you had to worry about DOF and what you f/number setting was. Scott > > ...Speaking of lasers... do holograms have bokeh or is that sort of > > negated by the fact that all of the light rays used to take them with [quoted text clipped - 19 lines] > > Scott What would you get if you made a hologram of an actual lens with an object behind it, would the hologram show the bokeh of the lens's image? Just a thought... SNIP I use to > shoot a lot of holograms and one of my tricks I would play on people > would be to leave the object that the hologram was taken of in place > and have people view the holograms. They would claim they could not > see the hologram until I had them put their hand between the holograms > and the object, and of course you can still see the object. SNIP Should have tried it with a skull and a real person sitting where the skull would be, fo split lighting on the real person (axes optional ;-)), darken the real persons side of the face with a fill light on a dimmer switch and you could have gotten "The Incredible Melting Face" for Halloween. Sort of like a real 3D version of the "Portrait of Dorian Gray", add Zach Braff from "SCRUBS" and Grey's anatomy and Bones and you could have "Portrait of Dorian on NBC/Fall Season Line up Sneak Preview", slogan could be "NBC... Face it... Our shows rot" ;-) LOL The progression... Bass-O-Matic Betamax Radio TV Color TV Extended Definition TV High Definition TV Ultra High Definition TV Holographic 3DTV Holographic 3DTV in Smell-O-Vision ("Yes It Really Stinks") 2027 A.D. NBC fall line up on Holographic 3DTV in Smell-O-Vision ("Yes It Really Really Stinks") "The Matrix" Tivo (in case you missed "The Matrix" and want to view it in flexitime) "My Mother The Car" World War IV in HD replaced by an old repeat of "Will & Grace" "Bartleby Jones" Tivo again (in case you missed World War IV b/c you were numing your popcorn while the world was getting nuked and you wanted to watch it all again in flexitime after the EMP effects or the melted butter wore off) World War V (for those who've missed world wars III and IV and forgot to buy Tivos, World War V is just a rerun of World War IV but without the commercials...) "Hawaii 50" Stone age people (no, not the cast of "Murphy Brown!) in loin cloths talking into conch shells in loin cloths with whiny little Don Pardo voices in loin cloths around a campfire in loin cloths pretending they're broadcasting on radio again adjusting tiny stones on big rocks pretending to Tivo their own "broadcasts" -- in loin cloths Morlocks in loin cloths in outer space, watching reruns of "The Matrix" and "The Time Machine" on their Tivos casually munching Eloi for snacks - "Now that's brain food!" "The Matrix in NBC fully censored HD Loincloths" (foreign title is "Rocky XXXXXXXXX to the power of MCM") "Young Frankenstein" unnoticingly replaced by an endless Tivo'd loop of Janet Jackson covering her wardrobe malfunction "Designing Women" World War VI (sorry, Tivo box being repaired, must re-stage the war live for all mutants who are left to see it) Kodachrome II Betamax Good bokeh!!! Oh yeah... and Bass-O-Matic again Scmidgital (schmuckle with bokeh and seven lively seasonings) "That 7000000000000000000000s Show" (The Stoned Age again) Full circle... OK well, full eliptical qualities of existence anyways... "Papshmear?" > Should have tried it with a skull and a real person sitting where the > skull would be, fo split lighting on the real person (axes optional [quoted text clipped - 4 lines] > and you could have "Portrait of Dorian on NBC/Fall Season Line up Sneak > Preview", slogan could be "NBC... Face it... Our shows rot" ;-) LOL This is very doable and a pretty weird effect. The other thing that is very hard to get use to is looking through the hologram and reaching around to the object that is still there. If you are only lighting up the hologram and not the object you can see the object right where it is and you can feel it right where it is but you can see your own hand, this is very unsettling. The other thing that is fun to do is take a hologram with your hand in it. For an object to show up in a hologram it has to stay still to less then a wave length of light during the exposure. I would expose anywhere from 5 second to 1 minute so there was now way for you hand to say still, even 1/1000 of a second would be far too long. The result is that where you hand is just black, a void. But the void is three-dimensional. You can't see through it but there is just nothing there, it is like a bit of space has been removed. Scott SNIP > The other thing that is very hard to get use to is looking through the > hologram and reaching around to the object that is still there. If you > are only lighting up the hologram and not the object you can see the > object right where it is and you can feel it right where it is but you > can see your own hand, this is very unsettling. Why is that unsettling? -- wouldn't it be more unsettling to see your own hand grasp for the (holgraphic image) object and grasp at nothing but air? > The other thing that is fun to do is take a hologram with your hand in > it. For an object to show up in a hologram it has to stay still to [quoted text clipped - 6 lines] > > Scott That would have to be a pretty slow piece of film (I.S.O .0003 ;-) or you'd have to use a pretty dim laser and/or you'd have to place somekind of ND filter in front of the laser (and/or the film?) that wouldn't get fried by the heat of the laser. I've heard there is such a thing as either white light or rainbow holograms that are viewable without? a laser source? but for taking the original hologram, what would youdo to get such a slow exposure? If some kind of new technology semi-transparent plasma/LCD/LED/silicon etc. _recording_ media could be used (and later viewed) instead of film then are "digital holograms" a possibility or not enough MP of data would br available through this new "digigram" process to reconstruct a sufficiently detailed enough interference pattern/wavefront to generate the holographic image? Just a thought... Oh, no, I think I'm just about to invent HTV (Holographic TV as opposed to HGTV (the Home and Garden Television Netweork) - infommercials in 3D... bleccch! "But wait... now for a limited time only you can get a third set of Ginzu knives free" "But wait... there's even more... Call now and get a lifetime supply of Chia seeds with your order" But wait... there's even more than that... Now for a limited time only, you can..." > SNIP > [quoted text clipped - 26 lines] > without? a laser source? but for taking the original hologram, what > would youdo to get such a slow exposure? The film (well plates) had an ISO of about 0.04. I was normally using a laser that had an output of 20mw or so. The object I would shoot would be up to a foot or two across, so it was pretty dim illumination. In fact the hologram was often much brighter then the object. > If some kind of new technology semi-transparent plasma/LCD/LED/silicon > etc. _recording_ media could be used (and later viewed) instead of > film then are "digital holograms" a possibility or not enough MP of > data would br available through this new "digigram" process to > reconstruct a sufficiently detailed enough interference > pattern/wavefront to generate the holographic image? The holograms I made were on 4 x 5 glass plates and the interference pattern that was being captured to make the hologram was on the order of 500 line pairs /mm to 1000 line pairs /mm. Figure you need two pixels / line pair and you are looking at least 1 MP / mm^2, or about 13 GP for the whole plate. But you really only need about 1 mm^2 for a hologram to be useful so you could make a useful one with just 1MP. One of the demos I would do was to drop the glass plate and have it break in to many small pieces. You could pick up any piece and shine a laser through it and get an image of the whole subject. Different pieces would all give an image of the object but different ones would show it from a different point of view. Scott > > SNIP > > [quoted text clipped - 51 lines] > > Scott What would happen if you shined a separate laser through each of two or more pieces -- a room crowded with images of the same object seen from different angles? What would happenif you shined two or more lasers at different angles through the same broken piece of the hologram, the same image multiplied or multiple slightly different images? How about shining two lasers sotheir light paths would intersect/"interfere" at the same hologram (whether that was a brokne piece of hologram or the full thing? What would happen if you took/_exposed_ a hologram with multiple pairs of lasers intersecting/interfering from multiple angles -- multiple full images from different angles? a holomovie? a holoheadache? ;-) Could multiple red, green and blue lasers used to interfere with other multiple red, green and blue lasers form an equivalent white light laser hologram or would you need a whole spectrum of multiple lasers at slightly different frequencies from red to green to bluue to accomplish this if it is even accomplishable at all? Enquiring minds want to know ;-) > > > SNIP > > > [quoted text clipped - 73 lines] > slightly different frequencies from red to green to bluue to accomplish > this if it is even accomplishable at all? OK, here's a stupid thought, if X-ray lasers are possible then how > about radio waves or micro waves (someone is about to tell me they are > the same thing - I am not that hep on all of the subtleties of the > electromagnetic spectrum...) lasers? Pulse it fast enough and it could > be used for communications or frying birds in mid-flight befor they > could fly into the openings of jet engines... They probably are possible, but it's not a trivial matter to make even coherent x-rays.....Here is a link to the machine that they believe will do it..... http://www-ssrl.slac.stanford.edu/lcls/ > OK, here's a stupid thought, if X-ray lasers are possible then how > > about radio waves or micro waves (someone is about to tell me they are [quoted text clipped - 7 lines] > it..... > http://www-ssrl.slac.stanford.edu/lcls/ Thanks for the link, William :-) > [SNIP] > > [quoted text clipped - 3 lines] > > But then what do you make your aperture out of? SNIP ...butterscotch pudding - the x-rays that do get through taste better that way ;-). > Diffraction limitation and exposure time considerations aside. Can a > photon(s) squeeze through something this tight and still for some kind [quoted text clipped - 7 lines] > would you bracket exposures using this "lens" in centuries or light > years? Dark years? Dark Milleniums? Well I have seen F 1.0 lenses, but unless the lens can have an infinity diameter, f 0 seems rather impossible. P.S. So far out there, I don't care! > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 [quoted text clipped - 44 lines] > > --------------060707070207010600080301-- Couldn't the entire universe act as a lens and use gravity to bend the light waves... now if I can only find a piece of film that big ;-) I wonder if Pentax's ghostless SMC coating works in interglactic space?... LOL :-) > Couldn't the entire universe act as a lens and use gravity to bend the > light waves... now if I can only find a piece of film that big ;-) I > wonder if Pentax's ghostless SMC coating works in interglactic > space?... LOL :-) Galaxies certainy are massive enough to form gravitational lenses (predicted by Einstein and only observed since the early/mid 90's) and I believe that so-called "dark matter" has been observed to lens light as well. many examples in one image: http://csep10.phys.utk.edu/astr162/lect/galaxies/a2218lens.gif graphic: http://upload.wikimedia.org/wikipedia/en/0/02/Gravitational_lens-full.jpg Cheers, Alan Signature-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: Remove FreeLunch. > Going to the opposite extreme -- can an f/0 "lens" exist (other than in > the imagination or in the Twilight Zone?... Or, what would a 1mm f/1 rectilinear lens look like? > > Going to the opposite extreme -- can an f/0 "lens" exist (other than in > > the imagination or in the Twilight Zone?... > > Or, what would a 1mm f/1 rectilinear lens look like? I don't know about the size of it, since the laws of physics would probably be violated, but time would probably run backwards through that lens and you'd probably stand before the lens as an old man and the image that would be formed would be formed out the other end would be Britney Spears or a zygote, take your pick ;-). We could call it the "Oops I did it again!" lens. As the aperture was stopped down (?goed up?) an increasing sense of Deja vu' would ensue and the words "Cranberry sauce" or "I buried Paul" would form on your lips as sucking sounds prceeded from your lips until you vaccuumed up the whole Sea of Holes in your King Features Syndicate version of Yellow Submarine. "How do you find America?" "Take a left at Greenland". >>>Going to the opposite extreme -- can an f/0 "lens" exist (other than in >>>the imagination or in the Twilight Zone?... [quoted text clipped - 12 lines] > Holes in your King Features Syndicate version of Yellow Submarine. "How > do you find America?" "Take a left at Greenland". Here's a prototype: http://www.edgehill.net/1/Misc/photography/1mm-f1-lens/1mm_f1.jpg You have to crouch inside it to operate. > Diffraction limitation and exposure time considerations aside. Can a > photon(s) squeeze through something this tight and still for some kind [quoted text clipped - 7 lines] > would you bracket exposures using this "lens" in centuries or light > years? Dark years? Dark Milleniums? Millenia. The f number that describes an aperture is simply the focal length of the lens divided by the diameter of the opening (assuming it's round, a diameter equivalent value if not). So yes, you could have an f1,000,000 lens - for example a 1,000mm lens with an aperture 1/1,000mm in diameter, or, more practically, a 1/1000mm diameter pinhole, 1m away from the film plane. 1/1,000mm is getting 'a bit' close to the wavelength of light, though, so it is debatable whether you would get any image... A pinhole 1/100mm in diameter, 10m from your film plane would also be f1,000,000, obviously, and a bit more likely to give you an image. Whether an image so dim could actually be recorded is a different question altogether though. For the same reason, no, you can't have an f0 lens. For the aperture to divide _zero_ times into the focal length, the aperture would have to have an infinite diameter. f1 is a challenge because, as you can imagine, a 50mm (2 inch) aperture in a 50mm lens requires a huge piece of glass, and the rays passing thorough the edge of the aperture need to be bent a lot in order to get them to focus close to where the central rays do. That is, the growth of aberarations as lenses get faster is getting pretty extreme by the time you reach f1. f0.95 and f0.75 lenses have been made, and there are probably faster optics for special purposes, but you can see that an f0.5 lens, for example, is really ceasing to be a practical proposition, even though that (and faster) is certainly possible theoretically. But not f0. Peter > > Diffraction limitation and exposure time considerations aside. Can a > > photon(s) squeeze through something this tight and still for some kind [quoted text clipped - 34 lines] > > Peter Alright, then, Peter, couldn't, in theory, a large amount of f/1 or slower lenses take pieces/small segments of the image and when re-combined/stitched together in Big Think (a computer with infinite speed and infintie RAM and Photoshop to the power of verion 99999999999999999999999999999999999999999999999) give an effect similar to a well corrected f/0 lens? [SNIP] > > > Going to the opposite extreme -- can an f/0 "lens" exist (other > > > than in the imagination or in the Twilight Zone?... [SNIP] > > For the same reason, no, you can't have an f0 lens. For the > > aperture to divide _zero_ times into the focal length, the aperture [quoted text clipped - 18 lines] > 99999999999999999999999999999999999999999999999) give > an effect similar to a well corrected f/0 lens? f0 is infinitely faster than f1 - so you'd need an infinite number of such f1 lenses. Big Think could have told you that, but thought that "you're not going to like it..." and so kept quiet. Peter > [SNIP] > > > > Going to the opposite extreme -- can an f/0 "lens" exist (other [quoted text clipped - 32 lines] > > Peter True, Peter. Though no need to keep quiet about it and no need for Big Think, I assumed as much on my own -- I said it half in jest (don't know what the other half was ;-)). But in theory, and possibly in reality, you would not need an infinite number of lenses to approach the equivalent of an f/0 lens, just one lens moving at near infinte speed (do I hear warp factor 10 Mr. Scott?) taking multiple shots. Now a computer with enough RAM to piece this all together into one giant f/0 "satellite map" of the universe would be another story... >> Diffraction limitation and exposure time considerations aside. Can a >> photon(s) squeeze through something this tight and still for some kind [quoted text clipped - 32 lines] >lens, for example, is really ceasing to be a practical proposition, even >though that (and faster) is certainly possible theoretically. But not f0. For an object at infinity and an aplanatic lens in air, the theoretical widest aperture is f/0.5 (NA 1.0). Some lenses have been constructed which approach this limit, but you are unlikely to come across them. The widest I can recall being generally available commercially was f/0.95. For a lens system* using immersion oil with refractive index equal to that of the glass used, you can achieve NA = 1.4 (f/0.35). Such lenses are regularly used for microscopy (I have a couple in my drawer) but are of course bugger all use for general photography. *This includes a suitable condenser light source, which must also be oiled to the specimen slide. David SignatureDavid Littlewood > Diffraction limitation and exposure time considerations aside. Can a > photon(s) squeeze through something this tight and still for some kind [quoted text clipped - 7 lines] > would you bracket exposures using this "lens" in centuries or light > years? Dark years? Dark Milleniums? f/1,000,000 can exist. It's a ratio, after all, not a dimension. so, the dimension can be 1 mm (lots of photons) and the focal length that many mm (1mm into a 1 km fl). What rules here is the exposure (photons/second/area). With extreme apertures and 1/r^2 law, not many photos will fall on the detector/film at the other end in a reasonable time, so the detector/film will be exposed by "noise" (heat, gamma rays, etc.). f/0 would be infinitely wide, so meaningless. The bokeh depends on optical properties. You can surely calculate the time required yourself? at a given ISO: f/1 for 1/1000s === f/1,048,576 for 34.84 years not accounting for reciprocity failure, of course. Cheers, Alan Signature-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: Remove FreeLunch. > > Diffraction limitation and exposure time considerations aside. Can a > > photon(s) squeeze through something this tight and still for some kind [quoted text clipped - 38 lines] > -- [SI] gallery & rulz: http://www.pbase.com/shootin > -- e-meil: Remove FreeLunch. If f/0 is an infinitely large aperture and can't exist then what about f/8 ? Wouldn't that be an infinitely small aperture with inifinite depth of field and form the non-image of an infinitely small?/large? headache at the film plane? At what point do mathematics and physics/physical reality breakdown in all these f/stop ratios? > > > Diffraction limitation and exposure time considerations aside. Can a > > > photon(s) squeeze through something this tight and still for some kind [quoted text clipped - 44 lines] > headache at the film plane? At what point do mathematics and > physics/physical reality breakdown in all these f/stop ratios? Apparently google's reality breaks down a lot sooner than my keyboard (option key + the number 5 key on my Mac), I typed in f/ and the infinity sign and they munged it into f/8 instead. The above paragraph should read... If f/0 is an infinitely large aperture and can't exist then what about f/infinity ? Wouldn't that be an infinitely small aperture with inifinite depth of field and form the non-image of an infinitely small?/large? headache at the film plane? At what point do mathematics and/or physics/physical reality breakdown in all these f/stop ratios? Or is it all just different levels of quantum "slippery math" from the mirco to the macro/universal. Besides me,does the universe have a few marbles loose and/or is both "actual reality" and the way we describe it just an infinitely slippery slope - and how/when does one where galloshes to keep from slip sliding away on this relativistic terrain? I guess at some point the mind's eye becomes the f/stop as observation affects results/reality? Am I getting warm or am I just "cosmic sneezing" (left nostril f/0 and right nostril f/infinity ;-)) the math/reality away? >> If f/0 is an infinitely large aperture and can't exist then what about >> f/8 ? Wouldn't that be an infinitely small aperture with inifinite [quoted text clipped - 21 lines] >results/reality? Am I getting warm or am I just "cosmic sneezing" (left >nostril f/0 and right nostril f/infinity ;-)) the math/reality away? Try Googling "Airy Disc". (Note - not Airey, though since many people mis-spell it, you may find it there as well.) You will find that the diameter of the diffusion disc (to the first dark band) is given by D = 2.44*lambda*N, where lambda is the wavelength, and N is the f-number (NOT the aperture). Note that the outer rings in practice make the image size greater than this. The image created by a point source of 550 nm yellow light from an f/1,000,000 aperture (i.e. N = 1,000,000) would give an airy disc of over 1 metre (2.44*550*10^-9*10^6). IOW, a meaningless mush. This would be true whether the lens was a 1,000 metre lens with an aperture of 1 mm, or a 50 mm lens with and aperture of 50 nm. David SignatureDavid Littlewood > Try Googling "Airy Disc". (Note - not Airey, though since many people > mis-spell it, you may find it there as well.) You will find that the [quoted text clipped - 9 lines] > This would be true whether the lens was a 1,000 metre lens with an > aperture of 1 mm, or a 50 mm lens with and aperture of 50 nm. OK so you just need a real big 'film' plane for this lens. 1km long, so say around 3,000m 3km wide film for a 6MP image. > If f/0 is an infinitely large aperture and can't exist then what about > f/8 ? Wouldn't that be an infinitely small aperture with inifinite > depth of field and form the non-image of an infinitely small?/large? > headache at the film plane? At what point do mathematics and > physics/physical reality breakdown in all these f/stop ratios? I don't where in school you missed that x/0 tends towards infinity. That's the only point where it breaks down mathematically. eg: x/0.0000000001 is "huge" compared to x/0. Physically it breaks down where the diameter of the hole is so small that light cannot pass at the wavelengths of interest. (Which is why I took the "mm" sized aperture approach with a very long lens where everyone else took the tiny aperture "normal" lens approach. Once you get down to sub-mm apertures the difraction effects will soften the image a lot and at some point (many micrometers) the image will be useless. Further down visible light won't pass at all (begining at wavelengths of 700nm and lower.) f/8 simply means the focal length is 8 times longer than the diameter of the aperture, a relatively easy concept, I would think? So f/1000000 requires a tiny aperture or a very long lens (better: both), but difraction effects have to be avoided as do wavelength filtering. Stop down your lens (DOF preview or Bulb setting with shutter) and look at it from the front. Imagine the focal length of the lens (from the film plane) v. the aperture you see. Surely that's enough? Cheers, Alan Signature-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: Remove FreeLunch. >So f/1000000 requires a tiny aperture or a very long lens (better: >both), but difraction effects have to be avoided as do wavelength >filtering. Alan, diffraction is a function of f-number, not absolute aperture size. Makes no difference if you use a 1,000m FL lens with 1mm aperture. See other post. David SignatureDavid Littlewood >> So f/1000000 requires a tiny aperture or a very long lens (better: >> both), but difraction effects have to be avoided as do wavelength [quoted text clipped - 3 lines] > Makes no difference if you use a 1,000m FL lens with 1mm aperture. See > other post. I was wondering about that as I wrote it ... I always thought the slit had to be closer (really closer) to the wavelength to cause difraction. We get all goosy about f/22 and tighter beginning to have difraction effects where large format photogs have no qualms about f/64... Signature-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: Remove FreeLunch. > >> So f/1000000 requires a tiny aperture or a very long lens (better: > >> both), but difraction effects have to be avoided as do wavelength [quoted text clipped - 6 lines] > I was wondering about that as I wrote it ... I always thought the slit > had to be closer (really closer) to the wavelength to cause difraction. Any slit will cause diffraction, but larger one diffract over smaller angles. > We get all goosy about f/22 and tighter beginning to have difraction > effects where large format photogs have no qualms about f/64... f/64 in LF will make just as large a blur circle as f/64 will in 35mm. Scott >>>>So f/1000000 requires a tiny aperture or a very long lens (better: >>>>both), but difraction effects have to be avoided as do wavelength [quoted text clipped - 14 lines] > > f/64 in LF will make just as large a blur circle as f/64 will in 35mm. Then that's why it's tolerated in LF... makes proportionally smaller blur circle over the whole image. Signature-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: Remove FreeLunch. >>> So f/1000000 requires a tiny aperture or a very long lens (better: >>>both), but difraction effects have to be avoided as do wavelength [quoted text clipped - 9 lines] >We get all goosy about f/22 and tighter beginning to have difraction >effects where large format photogs have no qualms about f/64... Well, 5x4 involves a whole lot less enlargement than 35mm, so there is a lot more resolution to "spare", or IOW the size of the Airy disc on the finished product will be relatively smaller. David SignatureDavid Littlewood > We get all goosy about f/22 and tighter beginning to have difraction > effects where large format photogs have no qualms about f/64... The aperture of diminishing returns varies with format. From testing I have found: Format Optimum aperture - where closing down any more makes things visibly worse 35mm f8 6x6 f11 4x5 f22 8x10 f45 Lens focal length didn't seem to have a lot to do with it. As always, YMMV. SignatureNicholas O. Lindan, Cleveland, Ohio Darkroom Automation: F-Stop Timers, Enlarging Meters http://www.nolindan.com/da/index.htm n o lindan at ix dot netcom dot com > > We get all goosy about f/22 and tighter beginning to have difraction > > effects where large format photogs have no qualms about f/64... [quoted text clipped - 15 lines] > Lens focal length didn't seem to have a lot to do with it. > As always, YMMV. This depends on how good your lens is and how flat you are holding the film. Assuming a good lens, the same film and reasonably flat film you should see this get bad at the same f/number regardless of the format. As you have already noted it does not matter what the FL of the lens is. So take the case of a 100mm lens in front of 35mm film and 100 mm lens in front of 4 x 5 film, how is the center 36mm x 24mm piece of film going to know what format camera it is from? Of course the design on the 4 x 5 lens is harder because it is much wider angle and so if the lens is not got aberrations might limit you more then diffraction. Your f/8 number seems pretty optimist I would be pretty surprised to see any visible degradation until you were past f/11 and even at f/16 it would take a pretty sharp image to see it , assuming you are using film. Scott >>We get all goosy about f/22 and tighter beginning to have difraction >>effects where large format photogs have no qualms about f/64... [quoted text clipped - 6 lines] > > 35mm f8 > Lens focal length didn't seem to have a lot to do with it. > As always, YMMV. Certainly. With some of my 35mm lenses peak measured sharpness is at about f/16 and others at somewhere between f/8 and f/11. Signature-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: Remove FreeLunch. >>>We get all goosy about f/22 and tighter beginning to have difraction >>>effects where large format photogs have no qualms about f/64... [quoted text clipped - 10 lines] >Certainly. With some of my 35mm lenses peak measured sharpness is at >about f/16 and others at somewhere between f/8 and f/11. Assuming it is not a DoF issue (and I know you are smart enough not to get confused by this), maximum sharpness at f/16 is not a good advert for the lens in question. A really outstanding lens for 35mm (which includes most top enlarging lenses) will give best resolution at f/5.6. A merely very good or good lens will peak at f/8. For a lens to have a (necessarily lower) resolution peak at f/16 suggests poorly corrected aberrations. Of course, contrast may improve a stop or two down, and this can sometimes make the perceived sharpness increase on a cursory examination. David SignatureDavid Littlewood > A really outstanding lens for 35mm (which includes most top enlarging > lenses) will give best resolution at f/5.6. That is what I was expecting ... that Summicrons and Micro-Nikkors would be best at ~4-5.6 and cheaper lenses at F8+. Surprisingly it was f8 across the board. There was some variation but it was on the level of noise in the experiment. > Of course, contrast may improve a stop or two down, and this can sometimes > make the perceived sharpness increase on a cursory examination. Well, perceived sharpness when reading an AF resolution chart image on a Tech-Pan negative with a research microscope was the methodology. There was quite a bit of judgement doing it this way: eye fatigue, the effect of lunch and coffee. SignatureNicholas O. Lindan, Cleveland, Ohio Darkroom Automation: F-Stop Timers, Enlarging Meters http://www.nolindan.com/da/index.htm n o lindan at ix dot netcom dot com >> A really outstanding lens for 35mm (which includes most top enlarging >> lenses) will give best resolution at f/5.6. [quoted text clipped - 11 lines] >was the methodology. There was quite a bit of judgement doing it >this way: eye fatigue, the effect of lunch and coffee. Hm, maybe just enlarging lenses then... There are two factors I suppose tilt it this way: (1) the magnification factor makes diffraction effects much larger in this application, and (2) enlarger lenses tend to be optimised for a limited range of conjugates, whereas camera lenses require to work over a wider range. Microscope lenses, which of course are designed for use at a fixed object distance, give maximum resolution wide open. I suspect process lenses are similar, but these are outside my experience. David SignatureDavid Littlewood >>>> We get all goosy about f/22 and tighter beginning to have difraction >>>> effects where large format photogs have no qualms about f/64... [quoted text clipped - 18 lines] > (necessarily lower) resolution peak at f/16 suggests poorly corrected > aberrations. Just looking at a variety of MTF charts (various manufacturers measured independantly by photodo or Chasseur D'Images) that show peak sharpness is at anywhere 'tween f/8 to f/16 by lens manuf/FL/speed (and FL for zooms). Often the curve from f/8 to f/16 (ish) is flat enough as to really not matter; and for that matter, not significantly sharper than f/8. Signature-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: Remove FreeLunch. > >So f/1000000 requires a tiny aperture or a very long lens (better: > >both), but difraction effects have to be avoided as do wavelength [quoted text clipped - 3 lines] > Makes no difference if you use a 1,000m FL lens with 1mm aperture. > See other post. Yes, this is true IF you correct the f number for increased extension. That is, at high macro you'll find more diffraction than you'd expect just by looking at the aperture number that you've set on the lens. If you take the bellows extension factor that you need to apply to correct the exposure, and use that to come up with a corrected f number, then _that_ is the 'reference' stop for how much diffraction will affect your image, not the marked stop. Peter > > > Diffraction limitation and exposure time considerations aside. > > > Can a photon(s) squeeze through something this tight and still [quoted text clipped - 45 lines] > headache at the film plane? At what point do mathematics and > physics/physical reality breakdown in all these f/stop ratios? what you're missing is this; the complex numbers violate a basic law of algebra, A != A, as in, the algebra of complex numbers state that A = A, whereas with most other algebraic structures, A != A. this is the source of not being able to divide by zero. another way of looking/thinking about this is that the mathematical continuum and the physical continuum are _not_ the same. in mathematics, there always exists an A, B, and C such that; A < B, B > than C, and A > C. in physics, it is easy to find an A > C, as well as a B that is indistinguishable from A _or_ C, as in B = A, and B = C. SignaturedonLouis papaindia (at) comcast (dot) net > > > > Diffraction limitation and exposure time considerations aside. > > > > Can a photon(s) squeeze through something this tight and still [quoted text clipped - 62 lines] > donLouis > papaindia (at) comcast (dot) net Too many numbers (Alan - though I think you might have been responding to my f/8 comments before I corrected them to what I typed/intended which was f/infinity - thanks for the links, though) and letters don, though I appreciate the efforts -- me mind is melting. Mathematically, on a good day, I can tie my shoes or my pants without either tripping me up/falling down ;-). The only thing I get from all this is that "real reality" and mathematical reality are two separate things and one tastes better than the other depending on which side of the aperture one stands :-). It does make me think/wonder that if we were all shrunk down to the size of a quark or so whether all would be darkness b/c we would be too small for light waves (or particles, whichever you prefer) to knock us on our a.ses much less enter through our pupils/eyes... > The only thing I get from all this is that "real reality" and > mathematical reality are two separate things and one tastes better > than the other depending on which side of the aperture one stands :-). you know, i never thought of it that way before... > It does make me think/wonder that if we were all shrunk down to the > size of a quark or so whether all would be darkness b/c we would be > too small for light waves (or particles, whichever you prefer) to > knock us on our a.ses much less enter through our pupils/eyes... strictly speaking, it would be "dark", insomuch as quarks "exist" on a level smaller than subatomic. SignaturedonLouis papaindia (at) comcast (dot) net >> The only thing I get from all this is that "real reality" and >> mathematical reality are two separate things and one tastes better [quoted text clipped - 9 lines] > strictly speaking, it would be "dark", insomuch as quarks "exist" > on a level smaller than subatomic. Yes.....At some small enough level, light becomes a macro concept...... > >> It does make me think/wonder that if we were all shrunk down to the > >> size of a quark or so whether all would be darkness b/c we would be [quoted text clipped - 6 lines] > Yes.....At some small enough level, light becomes a macro > concept...... i suppose that it is possible that there exists an energy suitable for a visual apparatus. i tend to think, however, that due to the high rate of speed at the quantum level, that clairvoyance/clairaudience would be more useful. SignaturedonLouis papaindia (at) comcast (dot) net > > >> It does make me think/wonder that if we were all shrunk down to the > > >> size of a quark or so whether all would be darkness b/c we would be [quoted text clipped - 15 lines] > donLouis > papaindia (at) comcast (dot) net ..."In space, Con Edison can't hear you scream" ;-) > f/0 would be infinitely wide, so meaningless. An f/0 lens of finite width is possible if the focal length is 0mm. I suspect a retrofocus design will be necessary, otherwise the light falloff towards the edge of the frame might be quite noticeable. SignatureMatthew Winn [If replying by mail remove the "r" from "urk"] > > f/0 would be infinitely wide, so meaningless. > [quoted text clipped - 5 lines] > Matthew Winn > [If replying by mail remove the "r" from "urk"] Yes, but can you get it in Pentax, Nikon or Canon mounts? ;-) >> f/0 would be infinitely wide, so meaningless. > >An f/0 lens of finite width is possible if the focal length is 0mm. >I suspect a retrofocus design will be necessary, otherwise the light >falloff towards the edge of the frame might be quite noticeable. Afraid not. David SignatureDavid Littlewood > P.S. - What's the bokeh like on an f/1,000,000 (?pinhole?) "lens" and > would you bracket exposures using this "lens" in centuries or light > years? Dark years? Dark Milleniums? Light year is a measure of distance - about 365.24*24*3600*3*10^8m. To answer your question, light years only if the bracketing is descibing how much the camera moves between exposures. /Martin Martin S?rensen wrote: > > P.S. - What's the bokeh like on an f/1,000,000 (?pinhole?) "lens" and > > would you bracket exposures using this "lens" in centuries or light [quoted text clipped - 5 lines] > > /Martin I know, Martin, it was a joke ;-) > an f/1,000,000 (?pinhole?) "lens" and > would you bracket exposures using this "lens" in centuries or light > years? Dark years? Dark Milleniums? As mentioned that would work with a 1 mm pinhole and 1,000,000 mm (1 km, 0.6 miles) focal length. Who knows, it might work nicely for shooting the sun though you'd need a hell of a crane to point it up & track with... that's a long toilet paper tube! Math assignment for those capable or inclined: How big would the bottom of the tube/film/sensor need to be to fit the sun? SignaturePaul Furman http://www.edgehill.net/1 Bay Natives http://www.baynatives.com > > an f/1,000,000 (?pinhole?) "lens" and > > would you bracket exposures using this "lens" in centuries or light [quoted text clipped - 13 lines] > Bay Natives > http://www.baynatives.com ...At least over 870,000 miles, but the real big problems are pushing the sun down the tube and keeping the tube from melting in the first place ;-) >>>an f/1,000,000 (?pinhole?) "lens" and >>>would you bracket exposures using this "lens" in centuries or light [quoted text clipped - 11 lines] > the sun down the tube and keeping the tube from melting in the first > place ;-) I think this one wouldn't be wide enough and it seems there is some worry about piercing the atmosphere: <http://educate-yourself.org/zsl/zslonekilometercloudbuster7sep02.shtml> video: http://www.enviromission.com.au/project/video/video.htm OK I need to get some stuff done... LOL > >>>an f/1,000,000 (?pinhole?) "lens" and > >>>would you bracket exposures using this "lens" in centuries or light [quoted text clipped - 18 lines] > > OK I need to get some stuff done... LOL The Solar Tower seems like a great idea -- an alternative alternative energy generator combining the best attributes of windmills and solar panels (what is that circle onthe ground, some kind of reflector to heat up the tower?) but the cloud buster rant is sheer beyond whacko -- angels and dead spirits in orbit (or at least between the Earth and the moon), I don't think even Jules Verne or The X-Files would have the cajones to touch that... well, maybe the X-Files. Scully and Mulder where are you? Got to go now... my Fruit Loops are receiving signals from the next realm... Elvis wants another stamp made of him and he's tired of hanging out at the SevenEleven to advertise it... LOL >>>>>an f/1,000,000 (?pinhole?) "lens" and >>>>>would you bracket exposures using this "lens" in centuries or light [quoted text clipped - 23 lines] > panels (what is that circle onthe ground, some kind of reflector to > heat up the tower?) I think it's more like a greenhouse to create heat to funnel up the chimney. > but the cloud buster rant is sheer beyond whacko -- Ha ha ha! 'The sky is falling!' > angels and dead spirits in orbit (or at least between the Earth and the > moon), I don't think even Jules Verne or The X-Files would have the > cajones to touch that... well, maybe the X-Files. Scully and Mulder > where are you? Got to go now... my Fruit Loops are receiving signals > from the next realm... Elvis wants another stamp made of him and he's > tired of hanging out at the SevenEleven to advertise it... LOL SignaturePaul Furman http://www.edgehill.net/1 Bay Natives http://www.baynatives.com SNIPS > > The Solar Tower seems like a great idea -- an alternative alternative > > energy gen |
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