ApolloHoax.net
Apollo Discussions => The Hoax Theory => Topic started by: Glom on November 17, 2012, 08:43:59 PM
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I'm sure this is relevant somehow. But I'm staring at these leaflets watching them change colour in the lighting of this establishment. One second the the "coming soon" circle is blue, the next its yellow. The strangest part is that the lights alternate between red and blue so where does the yellow come from?
It shows how weird perceptions can happen. Too often HB's fail to recognize the lack of common sense in what we see sometimes. The rigidity of their interpretations is their undoing.
(yes I'm also quite bored. 1hr 20m till chucking out time)
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The "coming soon" disk is "magenta" in colour
(http://www.infocellar.com/graphics/color-and-light/color_wheel-CMYadditive-and-RGBsubtractive.jpg)
In photography, colours are "additive" (RGB) and "subtractive" (CMY) but a lot can also depend on the "anomalous reflectance" of the ink or dye. Certain inks, dyes and bleaches can reflect more strongly in colours other than that which the eye sees. "Anomalous reflectance" is caused by high reflectance at the near infrared end of the visible spectrum, where the eye has little sensitivity. Its why photographing red flowers can be tricky. Also, ever noticed that in some photos, a bride's wedding dress can appear to have a blue colour cast? This is because some of the bleaches used to whiten the dress emit UV light, and while the human eye cannot see it, film and digital camera CCD can see but can only show it as a faint blue.
In your case, I am guessing that some sort of "subtraction" is going on, so when the lights go red, the red is being subtracted from the magenta being reflected by the impure spectra of the red light, giving yellow.
Just to give you an idea about impure colour spectra, lets imagine that we have two colour filters, a "perfect" blue filter and a "perfect"red filter (there is in fact no such thing as a perfect filter, but lets just assume for argument's sake, that they are perfect). Now we place the two filters, one on top of the other, and then hold them up to a white light. What colour would you expect to see?
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A lot of dyes, pigments, and light sources can have a rather limited number of discrete bands, causing unexpected results under colored illumination. It needn't even be very strongly colored...consider how different colors appear under sodium street lights. The spectrum looks like this:
(http://upload.wikimedia.org/wikipedia/commons/c/ca/Spectrum-hp-sodium.jpg)
Objects under sodium light often don't just look their normal color with a pinkish-orange cast. If a pigment reflects most of its light in the dark bands, it'll just look black under sodium light. Or it may reflect in an assortment of narrow bands, some of which fall in the dark areas of the spectrum, giving it a completely different appearance.
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The proliferation of LED flashlights is going to lead to all sorts of confused color perception. The more recent multi-color "white light" LEDs, like the tetrachromatics, render color better but the efficiency and price point of the blue-LED-with-YAG-"amber"-phosphor means they'll probably dominate the penlight and cell phone light market for years to come.
As a one-time theater designer, and an amateur graphic artist, I've already been in those horrible conversations with a client about what color something "really" is. I can only imagine how many more of those conversations are going to occur, as people take a cell-phone pic of their drapes, illuminated by warm-light CFLs, and then start an argument at the local Orchard Supply over the paint chip they are waving around under the high-pressure sodiums (or whatever high efficiency overhead lighting they are using now).
At least these days I only have to argue perceptual volume levels (usually trying to convince people the drummer hasn't gotten any less noisy, it is just that you've become habituated to it. Which usually happens right about the time hearing fatigue sets in and the high end begins to shut down and the same client begins complaining about the sound not being as bright and crisp as it was an hour ago.....)
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lets imagine that we have two colour filters, a "perfect" blue filter and a "perfect"red filter (there is in fact no such thing as a perfect filter, but lets just assume for argument's sake, that they are perfect). Now we place the two filters, one on top of the other, and then hold them up to a white light. What colour would you expect to see?
Black. (If you consider that a color.)
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I can only imagine how many more of those conversations are going to occur, as people take a cell-phone pic of their drapes, illuminated by warm-light CFLs, and then start an argument at the local Orchard Supply over the paint chip they are waving around under the high-pressure sodiums (or whatever high efficiency overhead lighting they are using now).
That's why any decent paint store will let you borrow their book of paint chips (or at least the chips of the colors you're considering) so you can take them home and see how they'll look under your own lighting and against your other furnishings.
The only remaining problem is that small samples don't look the same as an entire wall covered with the same color. The wall will look darker and/or more intensely colored than the chip. I learned that when I let my wife pick the new color for our internal walls. I don't like darkly colored walls (it's entirely pragmatic - it makes the room harder and more expensive to light) so I always opt for the lightest color she'll tolerate and then it'll be just barely bright enough for me.
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Which usually happens right about the time hearing fatigue sets in and the high end begins to shut down and the same client begins complaining about the sound not being as bright and crisp as it was an hour ago.....)
Having listened to my share of loud music in my youth, I now wish my high end would shut down -- at least when there's no external sound in that range.
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Having listened to my share of loud music in my youth...
Ditto, plus in my case a long string of increasingly powerful engines.
-- at least when there's no external sound in that range.
What? ;D
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Having listened to my share of loud music in my youth, I now wish my high end would shut down -- at least when there's no external sound in that range.
Ditto for me. Add in riding motorbikes.....
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lets imagine that we have two colour filters, a "perfect" blue filter and a "perfect"red filter (there is in fact no such thing as a perfect filter, but lets just assume for argument's sake, that they are perfect). Now we place the two filters, one on top of the other, and then hold them up to a white light. What colour would you expect to see?
Black. (If you consider that a color.)
Yep. You should see nothing at all. No light whatsoever would get though the filters.
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Tinnitus much?
I once had an episode of low-frequency tinnitus. I could only hear it when my ear was covered (like, lying on my side with my head on a pillow). It was a sort of thwupping sound, repeated about once a second... but with occasional pauses or delays. It was pretty maddening, but I could avoid it by lying on my back or other side.
My best guess is that I was having some sort of muscle spasm in the (inner?) ear, sort of "aural hiccups". It lasted about two days, then went away. It hasn't happened since.
ETA: in reply to ka9q, if it wasn't obvious.
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I once had an episode of low-frequency tinnitus. I could only hear it when my ear was covered (like, lying on my side with my head on a pillow). It was a sort of thwupping sound, repeated about once a second... but with occasional pauses or delays. It was pretty maddening, but I could avoid it by lying on my back or other side.
Sure you weren't hearing your own pulse? Given the ear's sensitivity, it's kinda surprising we don't hear the blood pulsing through the nearby capillaries more often, especially when your blood pressure is high.
My best guess is that I was having some sort of muscle spasm in the (inner?) ear, sort of "aural hiccups". It lasted about two days, then went away. It hasn't happened since.
The spasm could be in the stapedius or tensor tympani muscles. They're both in the middle ear where they form an AGC (automatic gain control) mechanism. The stapedius is attached to the stapes, one of the bones in the middle ear, while the tensor tympani is connected to the base of the malleus. The acoustic reflex causes them to contract involuntarily in response to loud sounds, dampening the motion of the bones and reducing the ear's gain.
The tensor tympani is controlled by the trigeminal nerve. I have periodic problems (trigeminal neuralgia) with that nerve, and in an episode several years ago that muscle contracted randomly without sound input. Very annoying.
Evolutionary trivia note: the three bones of the middle ear are a distinguishing feature of all mammals, evolving from what were originally bones in the jaw. Cetaceans (whales and dolphins) still listen primarily through their lower jaw bones.
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Sure you weren't hearing your own pulse?
That happens to me off and on. Usually when hiking up a long hill traverse at a fast pace. Occasionally when I have mixed coffee and pseudoephedrine. In either case it means I need to slow down what I am doing.
My hearing impairment, as a result of a misspent youth, means that some sopranos sound distorted. It is like they are overamplified through to small of a speaker.
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I once had an episode of low-frequency tinnitus. I could only hear it when my ear was covered (like, lying on my side with my head on a pillow). It was a sort of thwupping sound, repeated about once a second... but with occasional pauses or delays. It was pretty maddening, but I could avoid it by lying on my back or other side.
Sure you weren't hearing your own pulse? Given the ear's sensitivity, it's kinda surprising we don't hear the blood pulsing through the nearby capillaries more often, especially when your blood pressure is high.
Quite sure. It was neither correlated with my heart rate nor did it sound at all like the rushing of blood, which I have heard on a number of occasions. This was a very different sound, one I'd never experienced before or since.
Although it cleared up on its own it did give me some real sympathy for people who have long-term problems with tinnitus. I can see where it would drive you bonkers.
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...Too often HB's fail to recognize the lack of common sense in what we see sometimes. The rigidity of their interpretations is their undoing.
True. When I got seriously into photography in the early '70s I slowly became astonished over how lousy my perceptions had been of what I saw -- how many things I had "seen" but never really noticed and appreciated for what they really were.
I had always considered above-ground power and telephone lines to be ugly eyesores, but then I found that with the right lines and the right light of a low sun glinting off them, and with the right scenery and background, and the right exposure on the right slide film (prints from negatives are often useless), they could actually make surprisingly attractive photos.
Also, I had never noticed backlighting and rimlighting before. Later in the 70s and 80s, in winter I often went out for a lunchbreak to a nearby intersection where the low noon sun shone along one of the streets and beautifully rimlit the long hair and winter clothing of pedestrians as they crossed at the traffic lights. It was fantastic to relax and watch and appreciate over and over the sights which I had never noticed before getting into photography.
Sometimes I wonder if the "no stars" thing crops up because of movies and TV, particularly space stories. Of course there are always stars showing in bright sunlight (which is impossible in real life), but how often do they give us a vista of real, recognisable constellations? We can't expect to see those in the Star Wars movies because they are filmed "in a galaxy far, far away", but surely we should be able to see them in something that's set in our own solar system.
There's an ad on New Zealand TV at the moment which shows twinkling "stars" that look nothing like the real night sky, and in over 50 years of viewing them, I can only ever recall seeing one case of any fictional advertisement, TV programme or movie showing recognisable constellations. I was amazed!
Instead we often see the sort of nonsense like in (IIRC) the Leonardo DiCaprio movie The Beach. A girl in the tropics had a Hasselblad with a standard lens on a tripod, pointed the camera almost vertically up, and took time exposures of a few seconds. "So far, so good for once," I thought. "If we see the results there should be slightly streaked stars near the ecliptic." We did see the results, but they were very long exposures with stars circling the north celestial pole and taken from about 40 to 50 or even 60 degrees north latitude. To get just a slightly similar shot, with the pole star close to the horizon, the lens axis would have needed to be nearly horizontal.
Another thing that wakes us up regarding our perceptions is to see an extremely wide-angle photo of a recognisable scene, such as a shot of a long brick wall with the lens axis at right-angles to its centre. Often viewers will exclaim that the wall is distorted, but, except for the usual minor distortions of most lenses, that might not be the case. The main problem is that our brains are too good at reinterpreting things we see and making them acceptable to us. We need to study that wall from the same perspective as the camera, turning our head up, down and to both sides, and noting how the lines of of the bricks recede to a vanishing-point in all areas except those very close to the lens axis.
It can be quite startling to stand at the centre of an end wall in any large, rectangular room in a house and hold up two straightedges so that they match the joins between the side walls and ceiling or floor. Betcha your brain has been deceiving you all along over how sharply they converge to a vanishing-point.
Perceptions, experiences, emotions, memories and understanding are everything, and very important during circumstances which don't match any previous experiences we've understood.
I guess those are what make most of us poor eyewitnesses of any out-of-the ordinary or frightening event.
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When I got seriously into photography in the early '70s I slowly became astonished over how lousy my perceptions had been of what I saw -- how many things I had "seen" but never really noticed and appreciated for what they really were.
This is true for any synthetic lighting experience, including stage lighting. Expertise in lighting and composition for film or stage comes only after one has acquired a conscious awareness of one's perception of detail, form, contour, shadow, juxtaposition, luminosity, hue, and saturation. You can find any number of illustrations of these perceptual filters in the form of optical illusions, especially the ones that ask you to judge relative brightness.
Especially in cinematography, one's natural sense of hue and lightness must be explicitly overridden to accommodate lighting and film "temperatures." Having worked in theater for years, and having been a photographer for almost as many years, I was still also astonished when I began working in Hollywood. For example, the rich reds of TNG/Voyager Starfleet uniforms (as photographed) are actually almost a comical fuscia in natural light. The "black" parts are actually a surprisingly light gray. These costumes were designed by experts who knew not to trust their perception under the work lights, but who understood how the studio lights would "shift" their creation toward the actual intent.
Similarly I have watched novice scenic artists paint masterpieces as seen under the shop lights, but which turn to gray mush on stage. They failed to consult the lighting designer. If they want any sort of chromatic perception under subdued and possibly limited wavelengths, they need to make their piece look like someone threw up Skittles on it.
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Another thing that wakes us up regarding our perceptions is to see an extremely wide-angle photo of a recognisable scene, such as a shot of a long brick wall with the lens axis at right-angles to its centre. Often viewers will exclaim that the wall is distorted, but, except for the usual minor distortions of most lenses, that might not be the case. The main problem is that our brains are too good at reinterpreting things we see and making them acceptable to us. We need to study that wall from the same perspective as the camera, turning our head up, down and to both sides, and noting how the lines of of the bricks recede to a vanishing-point in all areas except those very close to the lens axis.
Thank heavens there are others that GET this!!!! I've had some extremely frustrating discussions with folks who maintain that straight lines are always straight, and that effects as wide-ranging as the Moon-tilt 'illusion' thru to fish-eye curvature of the view from a very short focal length lens are all nothing but illusions and lens effects..
I'm thinkin' about writing a web article about this topic, as I haven't found many decent references..
It can be quite startling to stand at the centre of an end wall in any large, rectangular room in a house and hold up two straightedges so that they match the joins between the side walls and ceiling or floor. Betcha your brain has been deceiving you all along over how sharply they converge to a vanishing-point.
That's one of the ways I try to explain it, but it seems it just doesn't get through - even to some folks who should really know better.
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Part of the issue is that artists "correct" what they "see" to match their perceptions, rectifying the primary object to be "square". Thus, we've been trained that this is how the world should be. Hence, view cameras where the focal plane is set parallel to the object to be photographed, squaring it up, because that's the most pleasing.
The difficulty is that there is no single objective reality. It depends on what you're trying to accomplish. An object that fills a frame with a long lens looks remarkably different than an image of the same thing taken with a long lens (Hitchcock and his cinematographer used this to remarkable effect in Vertigo by trucking the camera and changing the focal length of a zoom lens at the same time, keeping Jimmy Stewart the same size in the frame).
As I said, it depends what you're trying to accomplish. Just remember, never take a tight close-up of someone with a short lens if you want to stay friends...
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Having worked in theater for years, and having been a photographer for almost as many years, I was still also astonished when I began working in Hollywood. For example, the rich reds of TNG/Voyager Starfleet uniforms (as photographed) are actually almost a comical fuscia in natural light. The "black" parts are actually a surprisingly light gray. These costumes were designed by experts who knew not to trust their perception under the work lights, but who understood how the studio lights would "shift" their creation toward the actual intent.
You worked on TNG and Voyager? Tell us more!
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Jay, you have interested Graham again!
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*raises hand* I would also be interested to hear of this.
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You worked on TNG and Voyager? Tell us more!
I wish! I worked at Paramount (and Warner Bros.) on and off on other smaller projects for several years, commuting from Utah as needed. But I managed to spend a bit of time visiting Star Trek sets when they were open, and occasionally with the members of the cast and crew during their breaks. That's how I know what the costumes and other items look like in natural light. Previously I had met Patrick Stewart while I was working on the stage crew at Kingsbury Hall (Univ. of Utah) when Stewart was touring his one-man Christmas Carol. I wish I could say he remembered me when I ran into him again as Capt. Picard, but he did not.
I had more occasion to talk to the Voyager cast and crew, and to meet one of my acting muses Ethan Phillips. It was a bit surreal to share coffee with him while he was in Stanford sweats but full Neelix makeup. By that time most of the Star Trek stages were a little more tightly controlled, but it's amazing how far you can go with a "crew" badge. It also helps if you befriend minor cast members and the crew who will vouch for you. Normally in a major studio, the convention is that if a stage's "elephant door" is open, visitors can enter the stage. However, for Star Trek stages you still needed production-specific credentials to be on the stage, mostly because props and things had a habit of going missing, to be sold to collectors. I was surprised at how many extras and bit players were Star Trek fans, and had turned down other, better-paying work to get to be in a Star Trek episode.
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(Hitchcock and his cinematographer used this to remarkable effect in Vertigo by trucking the camera and changing the focal length of a zoom lens at the same time...
Dollying. Trucking is moving left or right, relative to the optical axis. Dollying is moving forward or backward along the optical axis. The cinematography term for this is simply the "dolly zoom," although it was referred to briefly as the "Spielberg zoom" when I was studying cinematography because the prevalent example of it had become Jaws. It's even a pre-programmed macro in some motion-control systems.
But yes, the proper distance from the subject versus the focal length is something you study also in still photography to properly compose a portrait and to properly manage the depth of field and focus. And you must be consciously aware of how the camera renders the impression of relative distance versus how your eyes perceive it. That it is typically unconscious in most people is how the dolly zoom achieves its unsettling effect.
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Hitchcock and his cinematographer used this to remarkable effect in Vertigo by trucking the camera and changing the focal length of a zoom lens at the same time, keeping Jimmy Stewart the same size in the frame
Thanks for that. I saw Vertigo about 1959-60 when I wasn't yet a teenager, so wouldn't have taken much notice of that effect, but when watching the DVD of Jaws a few years ago I certainly noticed, because that was the earliest example of it (1975) that I could recall, and I wondered who originated it.
Does anyone know exactly where that scene is in Jaws? From memory it's a shot of Roy Scheider sitting on the beach and he realises the shark is starting to "bother" people close to shore, round about the time that a dog disappears.
The effect is currently in an advertisement on New Zealand TV where a young couple is house-hunting. It's a view of them standing back-on to the camera and facing a house they like. The lens might have a bigger zoom range than the one in Jaws.
The DVD of Vertigo has been selling here for around $10 recently, so I must grab it. Maltin says it's a great film, and it lingered in my memory for a few years.
Just remember, never take a tight close-up of someone with a short lens if you want to stay friends...
Oh, I dunno about that. We have a lot of Polynesians in New Zealand and some have fairly flat, wide faces with even flatter and wider noses, so careful use of a shorter lens, closer in than usual, often gained me happy customers. Conversely, someone with a very long nose can be made to look better with an extra-long lens. The whole art of being a successful portrait photographer is, in some cases, re-interpreting reality. Painters have probably done that for centuries.
The difficulty is that there is no single objective reality.
A favourite escape clause of mine is, "Everything is relative and every situation is unique. Everything depends on something else." It got me out of all sorts of trouble.
A classic case is the derisive expression, "Aw, c'mon man, it's just common sense." For something to be common sense, you have to be in possession of the appropriate information.
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...the proper distance from the subject versus the focal length is something you study also in still photography to properly compose a portrait and to properly manage the depth of field and focus. And you must be consciously aware of how the camera renders the impression of relative distance versus how your eyes perceive it.
Getting a good full-face portrait on a large-format studio film camera of a long-nosed dog can be quite difficult. You need to know that you have sufficient depth of field to cover the distance between at least the tip of its nose and its eyes, but preferably its ears too, and often in a studio you won't be able to see exactly how much depth of field you have at a small aperture. You also need to know that about two-thirds of the depth of field will be sharp behind the point of focus, and one-third in front, and focussing on the appropriate point can be difficult if the dog isn't too happy about sitting or standing still.
It's worth studying similar photos to see if the photographer stuffed up. Some don't even try it. It might be easier when using digital cameras with their smaller image size, assuming that the manufacturers actually publish such esoterica as depth of field information.
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Thank heavens there are others that GET this!!!!
There certainly aren't many HBs who get it, just as there aren't many HBs who think to pause and spend a few seconds laying straightedges along the “parallel” shadows that Bennett and Percy show them on page 22 of “Dark Moon” and in their video, or the shadows that Sibrel shows them in his video, “A Funny Thing Happened on the Way to the Moon.” I suppose that the few who do have the brains to check don't claim the moonlandings are hoaxed because they already know that they've been taken in by people who deal in terminological inexactitudes.
...effects as wide-ranging as the Moon-tilt 'illusion'...
Haven't heard of that one, but I do know about the "gigantic" full moon as it rises behind a hill or distant trees.
It can be fun at any gathering where there is no moon visible, to hold up both hands with thumbs touching, fingers splayed, little fingertips and thumbtips in a straight line, and arms straight, and ask everyone to say how much of those two handspans they think it takes to cover the full moon, or even the rising full moon. It might also pay to say that those who know the exact answer should say nothing.
I've even had people say the whole lot -- 40 degrees roughly! Very few people will say that they could cover two moons with one fingertip and some may not believe the correct answer. It's an excellent example of how people perceive things -- even something they might have seen over and over for many years.
Another interesting way to mess with perceptions and maybe see the fur fly is, at a gathering of parents, ask the fathers if they would be perfectly happy for their teenage daughters to meet guys who are exactly the same as they were when they were teenagers.
Just be aware that it might pay to stand at least 1-1/2 arms-lengths from anyone you ask, and that doing so could cause a divorce!
I can honestly say that I'd prefer that my daughters did.
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There certainly aren't many HBs who get it, just as there aren't many HBs who think to pause and spend a few seconds laying straightedges along the “parallel” shadows that Bennett and Percy show them on page 22 of “Dark Moon” and in their video, or the shadows that Sibrel shows them in his video, “A Funny Thing Happened on the Way to the Moon.” I suppose that the few who do have the brains to check don't claim the moonlandings are hoaxed because they already know that they've been taken in by people who deal in terminological inexactitudes.
There's something else that a lot of people - HBs and otherwise - don't seem to understand that affects lunar shadows and a host of other things.
Anyone who has spent much time in a desert area is probably aware that while a surface can look relatively flat and level, when you begin to traverse the terrain it's likely to be very uneven; the combination of the nearly monochromatic surface and bright sunlight (with few shadows) tends to conceal the irregularities.
Looking at the images the astronauts took of the lunar surface, it mostly looks even, so when shadows - which of course follow the terrain - go in different directions, it just looks strange to the eye.
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(Hitchcock and his cinematographer used this to remarkable effect in Vertigo by trucking the camera and changing the focal length of a zoom lens at the same time...
Dollying. Trucking is moving left or right, relative to the optical axis. Dollying is moving forward or backward along the optical axis. The cinematography term for this is simply the "dolly zoom," although it was referred to briefly as the "Spielberg zoom" when I was studying cinematography because the prevalent example of it had become Jaws. It's even a pre-programmed macro in some motion-control systems.
But yes, the proper distance from the subject versus the focal length is something you study also in still photography to properly compose a portrait and to properly manage the depth of field and focus. And you must be consciously aware of how the camera renders the impression of relative distance versus how your eyes perceive it. That it is typically unconscious in most people is how the dolly zoom achieves its unsettling effect.
Don't ask me where I got trucking. I knew it was dolly.
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Does anyone know exactly where that scene is in Jaws? From memory it's a shot of Roy Scheider sitting on the beach and he realises the shark is starting to "bother" people close to shore, round about the time that a dog disappears.
I think so, but I haven't seen it in a while. Honestly, I think I've seen Vertigo more recently.
The DVD of Vertigo has been selling here for around $10 recently, so I must grab it. Maltin says it's a great film, and it lingered in my memory for a few years.
Yes, I believe it's one of Roger Ebert's Great Movies. And I trust Roger more than I trust Maltin, who's getting to be a bit of a corporate shill these days. Commentary tracks are one thing, but Disney seems to have Maltin on retainer these days. He hosts all of their fancy tinned box sets. While wearing a Mickey Mouse lapel pin.
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Even further offtopic..)
...effects as wide-ranging as the Moon-tilt 'illusion'...
Haven't heard of that one, but I do know about the "gigantic" full moon as it rises behind a hill or distant trees.
It's my personal favorite.. Pick a time when both Moon and Sun are in the sky but are a reasonable distance apart, around sunrise or sunset. Look at the angle from which the Moon is illuminated and mentally draw a straight line back to where the Sun *should* be... It misses by a significant margin! (which to some tinfoilhatters is proof that the sky/sun/moon is a hologram.. It's really quite a weird effect if you've never seen it before.
The reason for the 'illusion' (it isn't really an illusion at all) is simple perspective distortion - the same thing you get when standing near and beneath that long straight wall or standing on railway lines, the same thing that causes (anti-) crepuscular rays to fan out from the sun overhead and yet re-converge at the vanishing point on the opposite horizon. Apart from those that run along the horizon and those directly overhead, those rays *cannot* be straight lines *from our viewpoint* - after all, they go from the two vanishing points spread by 180 degrees, but then fan outwards up to 45 degrees as they go over your head - no straight line could do that... :P
But yes, of course the light rays do follow a straight line in 3d reality - it is the projection of that straight line on our 'spherical' - yet 2d - viewpoint that causes the curve (and it's a real curve..). I've probably described that badly, but it's hard to express in words..
Interestingly, the effect vanishes ('shifts' is a better word) if you alter your 'horizon' to match any curved ray, but by doing so, the actual horizon now becomes bent... The fascinating thing is that because we *always* perceive the horizon as level and straight, your brain doesn't like doing that and will do its best not to let you perceive the curve.
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That was a really good explanation. When I've tried to describe it I use an analogy of a great circle: the shortest distance between two points on the surface of a sphere is a great circle, now translate that up to the sky.
Over at the ATS forum there is a 40 page debate about the wet moon and dry moon.
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Even further offtopic..)
...effects as wide-ranging as the Moon-tilt 'illusion'...
Haven't heard of that one, but I do know about the "gigantic" full moon as it rises behind a hill or distant trees.
It's my personal favorite.. Pick a time when both Moon and Sun are in the sky but are a reasonable distance apart, around sunrise or sunset. Look at the angle from which the Moon is illuminated and mentally draw a straight line back to where the Sun *should* be... It misses by a significant margin! (which to some tinfoilhatters is proof that the sky/sun/moon is a hologram.. It's really quite a weird effect if you've never seen it before.
The reason for the 'illusion' (it isn't really an illusion at all) is simple perspective distortion - the same thing you get when standing near and beneath that long straight wall or standing on railway lines, the same thing that causes (anti-) crepuscular rays to fan out from the sun overhead and yet re-converge at the vanishing point on the opposite horizon. Apart from those that run along the horizon and those directly overhead, those rays *cannot* be straight lines *from our viewpoint* - after all, they go from the two vanishing points spread by 180 degrees, but then fan outwards up to 45 degrees as they go over your head - no straight line could do that... :P
But yes, of course the light rays do follow a straight line in 3d reality - it is the projection of that straight line on our 'spherical' - yet 2d - viewpoint that causes the curve (and it's a real curve..). I've probably described that badly, but it's hard to express in words..
Interestingly, the effect vanishes ('shifts' is a better word) if you alter your 'horizon' to match any curved ray, but by doing so, the actual horizon now becomes bent... The fascinating thing is that because we *always* perceive the horizon as level and straight, your brain doesn't like doing that and will do its best not to let you perceive the curve.
A really short lens (fisheye) will demonstrate that well: keep the horizon level, and every other horizontal line curves; select another reference, and the horizon curves. Of course, with that type of lens, there is deliberate barrel distortion in the entire image. Also, go to www.widescreenmuseum.com and look at any of the Cinerama images where the camera was panned up or down and the horizon is visible - because the image is on a flat plane (your monitor), and not a curved screen, you'll see a bent horizon.
If you think about it, every lens that images anything less that 180 degrees is really magnifying the center of that fisheye image, so the curves become less and less apparent. What lens makers work so hard at is managing edge distortion by keeping a straight line straight while maintaining focus to the edges of the frame. Poorly made lenses will exhibit either pin-cushion or barrel distortion. Actually, a well made lens has deliberate distortion to satisfy our perception of reality.
If you want to prove this to yourself, take a camera outside and shoot a 180 x 180 panorama using a normal lens (35 mm for most modern digital SLR,'s), and try to stitch the images together, without using a photo-stich software. You will find that there will be discontinuities at the edges of the images where the lens maker kept the lines straight (and now you know why you pick joining references in that software - they force a fix).
It's the inverse of the problem of matching aeronautical or nautical charts at the edges because the lines of latitude and longitude were kept straight.
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If you think about it, every lens that images anything less that 180 degrees is really magnifying the center of that fisheye image, so the curves become less and less apparent. What lens makers work so hard at is managing edge distortion by keeping a straight line straight while maintaining focus to the edges of the frame. Poorly made lenses will exhibit either pin-cushion or barrel distortion. Actually, a well made lens has deliberate distortion to satisfy our perception of reality.
There are actually several different types of projections that are possible. Fisheye lenses are generally a spherical projection that preserves solid angles...the image area an object occupies doesn't vary with its location on the image plane. Straight lines not passing through the axis project to curved lines, and distortion of shape becomes extreme towards the edges of the image. Real fisheye lenses often modify this for aesthetic reasons.
"Standard" rectilinear lenses are not just a fraction of a fisheye projection, they instead attempt to approximate a pinhole camera: straight lines in the scene project to straight lines on the image plane, but angular sizes are not constant along the image plane, spheres become distorted toward the edges, and it's geometrically impossible to have a view angle greater than 90 degrees from the camera axis (and in practice, extremely difficult to get very close to that).
Human vision is neither. Our view of our surroundings isn't an impression of light on a 2D image plane, it's a composite representation of a 3D scene cobbled together in our brain from two constantly moving eyes attached to an also-mobile head. Overall, there's a similarity to spherical projection, except without any conscious perception of distortion of straight lines.
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If you think about it, every lens that images anything less that 180 degrees is really magnifying the center of that fisheye image, so the curves become less and less apparent. What lens makers work so hard at is managing edge distortion by keeping a straight line straight while maintaining focus to the edges of the frame. Poorly made lenses will exhibit either pin-cushion or barrel distortion. Actually, a well made lens has deliberate distortion to satisfy our perception of reality.
There are actually several different types of projections that are possible. Fisheye lenses are generally a spherical projection that preserves solid angles...the image area an object occupies doesn't vary with its location on the image plane. Straight lines not passing through the axis project to curved lines, and distortion of shape becomes extreme towards the edges of the image. Real fisheye lenses often modify this for aesthetic reasons.
"Standard" rectilinear lenses are not just a fraction of a fisheye projection, they instead attempt to approximate a pinhole camera: straight lines in the scene project to straight lines on the image plane, but angular sizes are not constant along the image plane, spheres become distorted toward the edges, and it's geometrically impossible to have a view angle greater than 90 degrees from the camera axis (and in practice, extremely difficult to get very close to that).
Human vision is neither. Our view of our surroundings isn't an impression of light on a 2D image plane, it's a composite representation of a 3D scene cobbled together in our brain from two constantly moving eyes attached to an also-mobile head. Overall, there's a similarity to spherical projection, except without any conscious perception of distortion of straight lines.
No disagreement. I was just trying, in a simple fashion, to point out that anything less than a 180 view is section of the visible field., that's all.
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That was a really good explanation. When I've tried to describe it I use an analogy of a great circle: the shortest distance between two points on the surface of a sphere is a great circle, now translate that up to the sky.
Over at the ATS forum there is a 40 page debate about the wet moon and dry moon.
I haven't seen the ATS thread, and probably don't want to.. :P I think where the great circle explanation fails to get through is that the reader thinks the distortion is happening up in the sky.. when in reality the 'great circle' is in this case your curved retina and brain trying to perceive a straight line that:
- covers a very wide angle compared to our normal* f-o-v of say 20-40 degrees
- is neither directly above or to the side of the viewer's angle of view
Both of these factors are unusual for us..
* - I mean normal for perceiving/measuring straight lines or segments thereof..
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When I've tried to describe it I use an analogy of a great circle: the shortest distance between two points on the surface of a sphere is a great circle, now translate that up to the sky.
It's counter-intuitive. People sometimes have a hard time believing that a Great Circle route is shorter... but it means constantly adjusting your course. A rhumb line maintains a constant heading but is longer.
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It's counter-intuitive. People sometimes have a hard time believing that a Great Circle route is shorter... but it means constantly adjusting your course. A rhumb line maintains a constant heading but is longer.
A rubber band and a globe should be handy teaching tools.
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Human vision is neither. Our view of our surroundings isn't an impression of light on a 2D image plane, it's a composite representation of a 3D scene cobbled together in our brain from two constantly moving eyes attached to an also-mobile head.
A perfect description of what I was trying to say earlier.
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Part of the issue is that artists "correct" what they "see" to match their perceptions, rectifying the primary object to be "square". Thus, we've been trained that this is how the world should be. Hence, view cameras where the focal plane is set parallel to the object to be photographed, squaring it up, because that's the most pleasing.
The difficulty is that there is no single objective reality. It depends on what you're trying to accomplish. An object that fills a frame with a long lens looks remarkably different than an image of the same thing taken with a long lens (Hitchcock and his cinematographer used this to remarkable effect in Vertigo by trucking the camera and changing the focal length of a zoom lens at the same time, keeping Jimmy Stewart the same size in the frame).
As I said, it depends what you're trying to accomplish. Just remember, never take a tight close-up of someone with a short lens if you want to stay friends...
Well, to be more pedantic, visual artists developed "linear perspective" as a tool to create scenes with some illusion of depth. The methods are simple to learn and the look is codified, in large part because for moderate fields of view it "feels right" to the eye. Aka the closer you get to the center of the image, the closer the match is between the point focus of the human eye and the various approximations of artistic perspective.
Even then, many artists cheat it a little. Manga artists in particular have a couple of specific ways they juggle the mechanical perspective on objects that are close to frame edge/filling the frame (I'd look up the name of the one I know about but that would take about ten minutes of digging through reference books).
And when you really want to get crazy, you break out curvilinear perspective. Which can be a bear to plot out, is unusual enough to be exciting to look at, but is perhaps a little too much to use on every panel. Comic books and manga, in particular, are often about the clean, simple look, and the straight lines of linear perspective support that. Extreme case being funnies, where everything is flattened to the camera and depth is indicated only with depth planes.
I do know at least one web comic which is drawn almost entirely in curvilinear perspective, though, and once you tune in to the style it is quite comfortable to read.
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I do know at least one web comic which is drawn almost entirely in curvilinear perspective, though, and once you tune in to the style it is quite comfortable to read.
Linkage please? I'm curious to see it and could always use another webcomic to add to my list
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Might take a while. I archive-binged it, then realized what their update schedule was, and basically lost the link.
Or I'm confabulating, and the comic I'm actually remembering is Winter Melody. Which is worth a look anyhow. But I was so sure the one I was thinking of was in full color.....