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Post by JayUtah on Jan 23, 2007 3:14:55 GMT -4
The phenomenon of film saturation applies to the reflection question.
Let's consider the black-and-white case, understanding that it generalizes perfectly to the color case.
The light-sensitive part of film is an emulsion of photoreactive chemicals, such as silver salt crystals. As photons strike the crystals, they induce localized chemical changes to a degree proportional to the total number of photons. This geometric arrangement of radiometrically altered salts is called the latent image. Later, during development, the degree of change in the photoreactive salts translates to differences in opacity via a series of chemical reactions.
There are two reciprocal types of process: negative and reversal. Emulsions of both types begin transparent and remain transparent until the development stage. In negative emulsions, exposed areas turn dark (opaque). In reversal emulsions the exposed areas remain transparent and the unexposed remainder turns dark (opaque).
For the sake of discussion we'll use the descriptive terms conventional to the final image: exposed elements are considered to be bright or white; unexposed elements are considered dark.
The photochemical response is not infinitely proportional. A certain amount of light must initially strike the emulsion to get the reaction going. And after a certain amount of light has struck the emulsion, the reaction does not continue. The art of photographic exposure is the manipulation of the camera controls to restrict the amount of incoming light so that the proportional chemical reaction and the resulting eventual variation in lightness/darkness corresponds to the viewer's expectations from direct observation of the same scene.
Saturation occurs when the chemicals at a certain location have exhausted their ability to react to light. Further incoming light does not produce any additional effect in the latent image. Saturation appears white in the final image, corresponding to the viewer's expectated appearance of an excess of light. It's important to understand that when saturation occurs, the final image is no longer a reliable indicator of how much light has actually struck the film. A point on the image is just as white when scarcely saturated as it is when grossly saturated. This affects the interpretation of white saturated fields in the image: there is no justification to claim that the uniformity of the white saturated fields implies that an equal amount of light struck all portions of the field. Where the saturated field appears to represent the image of a physical object, you cannot claim that the object was uniformly lit on the basis of the uniform appearance of saturation.
Now we need to discuss the limitations of optical assemblies. There is no perfect reflector or refractor; all such elements scatter incident light to some extent. Generally the intensity of scattered light falls off according to the cosine of the angle of deflection. That is, if you were to shine a finely-focused laser beam through a typical optical assembly and expose the film to reveal the fall-off, it would appear as a small bright spot in the center of a circle that faded very rapidly the farther it got from the center.
Scatter affects all light that passes through the lens, but generally the amount of scatter occuring at ordinary light levels does not noticeably affect adjacent elements of the image. Scatter is not a concern for normal photography at normal exposures. However, when an element of the scene is several orders of magnitude brighter than its surroundings, such as the sun or reflections of the sun from an efficient reflector, scatter in the lens becomes important. The scatter becomes significant enough to affect the surrounding image, and may in many cases be intense enough to cause saturation. Thus it becomes impossible to distinguish the directly-focused saturated field from the larger surrounding scatter-saturated field. As various conditions change that affect only scatter, the size of a saturated field will vary.
Optical conditions in this category include lens element placement that changes with focus adjustments and zoom adjustments (if applicable), as well as exposure settings -- both aperture diameter and shutter speed. If the aperture is closed, admitting less light, the scatter may be reduced back into the film's normal dynamic range and appear as brighter tones of actual objects. Since film exposure is cumulative, shortening the shutter speed has approximately the same effect by reducing the duration of the photon fluence.
Chemical conditions apply too. There are different chemical formulations for photoreactive emulsions. A property of each is the function that defines the precise proportionality of chemical response to incident light. No film is purely linear, nor would a purely linear response produce realistic tones in the final image. But because some film responds according to higher-order functions, the degree to which varying amounts of scatter saturate the film varies from film type to type. Thus you cannot directly infer the similarity in strength of incident light from scatter-saturated fields in two different photographs taken on different film formulations.
Now we turn to electronic photography. The charge-coupled device (CCD) reproduces in semiconductor form the radiometrically proportional response of chemical film. Each element in a CCD matrix changes its electrical properties proportional to the amount of incoming light. After the image is accumulated in the CCD, the CCD's electrical properties are "read out" by the supporting electronic circuits and then the elements are reset. The intensity of light at each element (pixel) is represented as a digital number in any of several standard digital image formats. Like film, a CCD has a saturation point. And since the optics are no different in electronic photography, lens scatter is every bit as significant in electronic photography as it is in chemical photography.
CCDs have response curves as well. Early CCDs especially did not distinguish well between small differences in the higher (brighter) effective exposure range. Thus the CCDs tended to saturate more readily than film. This means that scatter-induced saturation was more of a problem in the early CCD cameras.
Prior to digital photography, a variety of analog electronic devices were employed based on cathode-ray tube principles. They are generally lumped under the term vidicon. These vidicon tubes were the primary means of television photography for decades, including during the Apollo era. As expected, they share many of the same properties as CCDs and chemical film, specifically in that they have response curves and can be saturated. And because the optical assemblies do not change, lens scatter is a problem.
The surface of the vidicon onto which the image is focused is made of a photoelectric chemical. As light falls on a spot, that spot acquires an electrostatic charge proportional to the amount of light. Behind it and separated by a semiconductor is a chargeable plate. This sandwich forms the receiver end of a cathode-ray tube. When a beam of electrons is focused on a point on the charge plate, its electrical response is governed by the degree of charge on the vidicon surface. The voltage on the charge plate is measured and correlated with the current position of the scanning electron beam in order to generate a continuous picture signal.
Since the surface discharges to the charge plate when the electron beam strikes, the surface is effectively reset for the next frame. However, under intense light conditions such as those that cause scatter-based saturation in film and CCDs, vidicons have an additional deficiency. They are still susceptible to scatter-induced saturation and have the early CCD's problem of poor response at the top of the dynamic range. But in addition, saturation results in electrical charges that propagate laterally across the vidicon surface. As a spot saturates, the excess charge moves to adjacent spots, often saturating them as well. This produces the characteristic "bloom", or expanded areas of saturation in the television image.
When the image of the feature causing the saturation moves across the frame, it may take several passes of the electron beam to discharge the supersaturated surface completely. The resulting visual artifact is a streak or 'tail" behind a moving bright object. This phenomenon must be considered when analyzing saturation effects in frames from vidicon-based videography.
Because of these two well-known effects, it can be stated as a general rule that videography using vidicons will produce larger, more pronounced saturation fields than either chemical or high-end CCD photography, all other factors being equal. It is most indefensible to try to infer the size of a feature from its saturation field in a vidicon image.
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Post by gwiz on Jan 23, 2007 4:51:19 GMT -4
Nice post, Jay, but he won't believe you. He'll say you are totally untrustworthy because you won't blame the evil government for 9/11 and the JFK assassination. He'll ask all his friends and they'll agree with him. It must be difficult for them all never to look at the photos they take.
Edit to add: 1000 up.
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Post by BertL on Jan 23, 2007 6:21:36 GMT -4
Well, so far he hasn't responded at all.
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Post by Grand Lunar on Jan 23, 2007 8:38:38 GMT -4
Patience. Must wait until the OP returns and is online.
When you do get here David, there's something else I'd like to know.
Why would Apollo be hoaxed? Was there some technical problem with the Saturn 5 that just couldn't be fixed? Was there something wrong with the Block 2 command module? Was there a problem with the LM that made it unsuitable for the missions it would carry out? Was/Is there some unknow factor in cislunar space or on the lunar surface that would prevent such a mission like Apollo from suceeding? What is it?
Oh yes, I want your thoughts on this. I want to know where you are coming from, not what other HBers think. Just you. And yes, I know you have the time. In the time it takes you to copy and paste links, you could certainly sit down and think of your own answers. That is, if you are serious about this subject.
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Post by JayUtah on Jan 23, 2007 11:09:26 GMT -4
Nice post, Jay, but he won't believe you.
He doesn't have to. Nothing I've said can't be verified by others experienced in photography. And because I've been fairly detailed in my descriptions, anyone (expert or layman) who can find the proper equipment and exerts himself to conduct his own tests can verify for himself that changes occur in the photographed reflection size that have nothing to do with the nearness or size of the light source.
Empiricism is a wonderful thing: it doesn't require anyone trustworthy to attest to it in order to give it value. So Dave can believe or disbelieve what he wishes, but he can't do anything about the readers who have all now been equipped with some of the tools necessary to investigate David Percy's claims by themselves.
This article is one of three or four I plan to write on this topic, time permitting. Yes, they're long and contain what some might consider irrelevant detail. I believe in putting into the reader's hands as much material as he needs in order to investigate David Percy's claims and to conduct further research on his own if he wishes. My willingness to go into whatever detail is appopriate stands in contrast, I believe, to the brevity in some of the conspiracy theories, whose proponents realize that lengthy discussion is simply more rope with which to hang themselves.
Here is David Percy's entire discussion on this point, from page 26 of Dark Moon (emphasis in original).
Just a few sentences that allege so much without providing any supporting evidence for the premises on which his conclusion is drawn. He provides examples of the observations he's trying to explain, but no theoretical discussion or empirical evidence that his explanation is based on demonstrably sound principles.
I don't currently have a Clavius page to address this point, but after our discussion it should be clear that Percy just jumped at his one hypothesis and ignored all other possibilities, as well as counterevidence (hard-edged shadows) against it.
He'll say you are totally untrustworthy because you won't blame the evil government for 9/11 and the JFK assassination.
Luckily I have faith in the reader to recognize when someone is trying to dodge responsibility for his statements.
He'll ask all his friends and they'll agree with him.
And if the universe behaved democratically, that would mean something. The universe does not alter itself based on our wishes or belief, or even the collective belief of thousands.
If you want to know the truth, ask someone with experience how you can go about finding it. If you want to comfort and reinforce your existing beliefs in the face of opposition, ask your friends.
It must be difficult for them all never to look at the photos they take.
I hear what you're saying, but here's where we have to grant some charity. Yes, people generally do not look at their own photography analytically or critically. Nor do most people observe their world analytically or correctly. The human visual cortex does a wonderful job of interpreting images automatically in ways that serve normal human needs. But that automatic interpretation abstracts away certain details that we need for deeper understanding, especially of photographs.
Learning to "turn off" one's intuitive and innate visual perception mechanism is the important prerequisite of photographic analysis, and also of creating representational art. Successful artists find it very easy to transition to photographic analysis. But it's not easy for some people to step outside their intuition and see photographs (or real life) in a purely analytical, abstract way. And there's not much anyone can do to help that process; it either "clicks" or it doesn't. If it never "clicks" then photo analysis is not a viable career path for you.
So from the point of view of those people, not much makes sense in the world of real photo analysis. It would be a natural reaction simply to dismiss it. We have to be careful not to attach too much value judgment to that. Part of the strength of the human race is that individual brains seem to be wired differently and thus more or less adaptable to some particular cognitive task.
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Post by JayUtah on Jan 23, 2007 12:26:04 GMT -4
One more important property of vidicons.
The electrostatic diffusion that causes blooming depends for extent only on the strength of incident light. That is, for some fixed light strength the electrostatic charge will migrate a certain absolute distance across the surface. The distance is not proportional to the size of the vidicon. So for some incident light strength, the bloom will extend a certain number of microns in all directions whether the vidicon is 5 millimeters or 5 meters across.
If the vidicon is small, the effect for some fixed light strength will be proportionally larger in the frame. Small vidicons bloom more than large vidicons. This is important because the miniaturized cameras supplied to Apollo had very small vidicons compared to those in studio television cameras. It would not even be valid to compare saturation fields between Apollo television cameras and, say, an Ikegami studio camera circa 1970. The Ikegami has a large vidicon for the same reason modern cameras use large CCDs and modern motion picture cameras use large film formats: all the absolute-size artifacts associated with photography are minimized when the image target is large.
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Post by JayUtah on Jan 23, 2007 14:30:31 GMT -4
Okay, Percy's argument on visor reflection is still bugging me. Maybe I had better strike while the iron is hot.
Refer to my earlier post for the uninterrupted reproduction of Percy's claims. I apologize for not being able to reproduce Percy's examples here. Suffice to say his "anomalous" examples are all vidicon television stills and his reference photographs are all film photography.
For those who can't refer to Dark Moon or the companion video, Percy raises the reflection argument as a supporting point to the discussion of his Photo Rule #1, which is the one arguing that parallel light rays must cast parallel shadows. The preceding sections examine photographs with allegedly anomalous shadow directions and conclude that an artificial nearby light source must have been used. The reflection section is meant as a secondary bit of evidence in favor of artificial lights -- one that's not tied to shadow analysis. A casual reading suggests that Percy has presented two independent arguments in favor of the photography having used artificial light.
At first we might fault Percy for considering two NASA-supplied photographs as accurate and reliable references and three other NASA-supplied photographs as examples of anomalies. That smacks initially of setting arbitrary goalposts. But to be fair Percy is trying to limit his examination to alleged photographs of sun reflections in space helmet visors. There's just a limit to the number of sources available for that photography. Yes, he might have gone to the Soviet space agency to get pictures of cosmonauts and their visors, but then we'd worry about whether Russian visors have similar optical properties to American visors. We might let Percy off by accepting that he's just testing NASA sources for consistency, but that's not really what he's doing. He seems to accept the McCandless photo as the "right" answer. It's not worth quibbling over whether Percy is inappopriately ambivalent on NASA's authority.
In Percy's television frames, he observes that the reflection occupies "at least 25% of the astronauts' convex visors." I'll stipulate to that observation, and to the comparison that the reflection in the television frames is significantly larger than those in the reference photographs, proportional to the representation of the visor proper. This frees us from quibbling over whether the reflection area or linear dimension is intended, and over whether the reflective portions of the visors differ between space suits.
This result is indicative of a light that is incredibly large and extremely close.
It might be too fine a dissection to ruminate over what Percy intends by "indicative". Specifically, "indicate" may imply necessity or it may imply mere possibility. Is it possible for a large nearby light source to produce such an effect? Unquestionably. But is it necessary to have a large nearby light source in order to achieve that effect? That's the sixty-four dollar question. We need to answer it as a matter of objective understanding, but we also need to discern accurately what Percy's argument purports.
Skipping ahead: An average of 237,800 miles difference between low Earth orbit and the lunar surface cannot increase the amount of sulight reflected in a visor to such an extent. I'll stipulate to what I believe Percy means to say. I think he means to say that the Earth-Moon distance is insignificant compared to the distance from cislunar space to the Sun. Thus moving from Earth orbit to the Moon won't change the apparent size of the Sun in the sky. And all other things being equal, it shouldn't change the size of a reflection of the Sun if you move that reflector such a proportionally short distance.
Percy guesses, and I agree, that NASA will claim the Sun is causing the reflection in both his reference photos and the television frames.
In our opinion these images could only manifest this result if photographed by the light of something other than the Sun.
This sentence sews the argument together. The Sun can't have changed apparent size under the conditions espoused by NASA. And the interpretation of the television frames is of a light source much larger and/or nearer than is apparently consistent with visor reflections of the Sun.
"Could only" clears up the question of necessity. Percy here argues that the nearness and/or size of the light is the "only" explanation for the observation to which I have stipulated. This arguably falls into the class of indirect arguments that I discuss at length at Clavius. These are misguided and fallacious attempts to prove what something is by proving instead what something is not. The reader is supposed to accept the proposition by process of elimination. But the elimination only works when the proponent has been exhaustive. If you propose to prove that a certain animal is a tiger by showing that it is not any other kind of animal (and therefore must be a tiger by default), then you have the burden of proof to eliminate each and every other kind of animal. If you omit an animal, your proof fails -- your candidate animal may either be a tiger or it may be the animal you forgot to eliminate.
And has Percy been exhaustive? Hardly! He hasn't even been cursory. He simply states as his "opinion" that the large reflection "can only" be the result of his hypothetical large, nearby light. Unfortunately whether such results "can only" come from that kind of light (and not, for example, from other effects that may legitimately occur in that kind of photography) is not a matter of opinion. It is a matter of testable fact.
Why does Percy appeal to opinion rather than the exhaustive eliminations we know must accompany the indirect argument? Because Percy represents himself as an expert on photography. He has spent the preceding two dozen pages giving his credentials and speaking otherwise from a position of assumed authority. When he gives his opinion here, he expects the reader to accept that opinion as the learned and well-researched opinion of an expert on the subject of photography and lighting. The reader may suspect that a number of potential factors may affect reflection size, but Percy asks him to trust that he -- the expert photographer -- has considered and eliminated them.
But Percy is not the only expert photographer in the world, and not all readers are obligated to take Percy's opinion as gospel. As we said, Percy's theory is testable and doesn't require being attested to by learned authority.
A brief anecdotal digression. My theater employs a professional photographer, Doug. Doug does all the promotional material, the cast photos, and generally undertakes any task for which professional-quality photography is required. Doug sometimes asks for my assistance. Every six months or so, Doug commandeers one of the large rehearsal halls and offers discounts on actor headshots. That's when he asks my assistance, usually to help him haul in from the parking lot and set up probably the largest softbox I have ever seen. The business end of it is about 12 feet square.
A softbox is a diffusive element placed over a standard studio light. Modern examples collapse flat and can be assembled on location. The principle by which they operate is the notion that a large translucent sheet of material placed some distance from a small light will effectively transform it into a large light. The entire diffusive surface glows with relatively uniform intensity, and sends light in all directions. Doug's subjects sit about ten feet away from the softbox. Portrait photography -- and actor headshots specifically -- thrive on soft lighting that reveals subtle contour and eliminates harsh or hard-edged shadows. The only way to achieve that effect is by a plethora of lights placed in different positions around the subject, or a single very large light that achieves the same plethora of lighting direction with a single instrument.
Why is that relevant? Because one effect of a very large nearby light source -- its principal desired effect and a necessary consequence of it -- is the softening of shadows and shade. Yet in Percy's three example television frames we see the hard-edged shadows we come to associate with other Apollo photography and which we expect in subjects lit by the Sun. This has already been addressed earlier in this thread. David Percy's hypothesis cannot explain all the evidence visible in the frames he has presented, therefore it cannot be considered a complete explanation for the lighting in them. A large nearby light source cannot produce a very large reflection in the visor and simultaneously a hard-edged shadow. And because Percy has styled his theory as the "only" possible explanation, demonstrating it to be incomplete defeats it.
Percy speaks as if from a position of authority on studio photography. He would thus be expected to know all about large-area light sources and why they're used and what effects they would be expected to produce in the image. That is basic lighting technique. If he failed to notice that effect in his examples, then his examination of the Apollo evidence cannot be considered thorough enough to make a meaningful statement regarding authenticity of the record. Others are demonstrably more thorough and arrive at different conclusions. If he noticed it but failed to address it, then it might be the case that he doesn' t know as much about lighting as he purports. In that case his opinion would have no value as proof. If he knowingly failed to address it, then he would be deliberately withholding important evidence that contradicts his belief.
Not only has Percy failed to explain all the evidence he presents, he has failed to explain by what means he eliminated in this case any of the other effects that might demonstrably affect the size of the reflection. Until he presents his cases on those effects we are not obligated to believe he has appropriately eliminated them.
The most salient potential confounding effect is the vidicon bloom principle we have belabored. It is a well-known, easily testable effect. It may not be an accident that all of Percy's allegedly anomalous photos were imaged on vidicon. For consistency's sake, wouldn't hoaxers use similar lighting for the Hasselblad photography? Why are there no allegedly anomalous Hasselblad photographs? If Percy were to present the 70mm film photography alongside the television frames, the reader might get the "wrong" idea that the size of the visor reflection correlates more closely to the choice of imaging technology than to whether the mission was to the Moon or to Earth orbit.
David Percy represents himself as a photographer, but also as a videographer and filmmaker. His resume photo shows him next to a video camera, suggesting he purports expertise both in film and in video. He appears old enough to have used vidicon-based video cameras. Whether he understands the physics behind vidicon bloom is not as important as the extreme likelihood under his claim to authority that he knows full well the significant difference in saturation behavior between film and vidicons. The reader has trusted Percy to inform him if there is any salient difference between video and film that might affect the conclusion, and Percy has failed.
Percy rightly identifies the distance between the light source and the reflector as a predictor of how big the reflection should be. That distance translates to the apparent size of the light source from the reflector's point of view. But he fails to consider the distance from reflector to camera. As reflections depart a convex surface, the light rays diverge even if the original incident light was parallel. This would occur even from a flat reflector due to scatter. The divergence means that visor highlights will eventually disperse if you get far enough away. But the basic nature of saturation means that the reflection will diverge and become larger before it falls below the saturation threshold and its structure is thus discernible on film. Percy does not consider whether the photographer's distance from the reflector might have affected the reflection size.
And so forth: convexity, exposure, film formulation. All these effects are known. They can be isolated tested and shown to have a significant effect on the size of a reflection. And not only did Percy fail to address and eliminate all of them before rendering his all-important opinion, he failed to address any of them.
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Post by Grand Lunar on Jan 23, 2007 14:59:17 GMT -4
I never knew an issue with a reflection was so complicated! A lot Mr. Windley knows.
I suppose this is one of Percy's lesser issues (if that term can be used). One that had me in stitches was Percy's claims regarding the Saturn 5 and the spac shuttle; how the shuttle's boosters are unrealible, and how the Saturn 5 could've been used to boost the shuttle into orbit instead, citing that this would be cheaper.
Certainly scores a 9.0 on my Say-what-O-meter.
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david
Venus
Account Disabled
Posts: 67
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Post by david on Jan 23, 2007 15:49:11 GMT -4
There's nothing rhetorical about my question. I don't see how anybody can say it's rhetorical with a straight face. It was a simple question about a simple picture. I guess everybody was afraid to answer it because they have to agree with the official government version of everything on this site and the official government version is obviously wrong. Well, sidestepping the question says a lot about your level of objectivity too. After seeing everybody's response I would say none of you are objective. I won't be able to post very much for about a week as I have to change residences. If I'm not banned, I'll be back.
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Post by scooter on Jan 23, 2007 16:05:11 GMT -4
David, If the picture was of the quality where I could see a Global Hawk, F-4 or very large duck, I would be right there saying so. Frankly, I just see something coming from the left. To me that's all it looks like, not a 757, not a duck...just a "something. Now, all the supporting evidence at hand says this blurry something is the 757 that hit the Pentgon...eyewitness accounts, recovered human remains, wreckage, radar and controller records...but the picture alone to me is still identifiable just looking at it as a "something". Now, if there was some extenuating evidence out there that said it's something else, hard evidence, I'm all ears.
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Post by JayUtah on Jan 23, 2007 16:56:26 GMT -4
There's nothing rhetorical about my question. I don't see how anybody can say it's rhetorical with a straight face.
"Rhetorical" doesn't just mean a question no one is expected to answer. Rhetoric is the art of effective persuasion in writing and speech. Specifically, you want to persuade people that we can't be trusted, but without having to address what we actually say.
Of course your question itself wasn't a "rhetorical question". Not only did you expect an answer, you expected a certain answer. You had an argument all lined up in the wake of that answer by which you proposed to do an end-run around all our well-supported statements and portray us as "somehow" unreasonable regardless.
It was a simple question about a simple picture.
Hogwash. It was a well-known, ham-fisted, high-school debate trick -- a failed ad hominem ploy to cast vague aspersions on statements you can't answer directly.
I guess everybody was afraid to answer it because they have to agree with the official government version of everything...
Now you're so desperate that you're putting words in people's mouths.
Well, sidestepping the question says a lot about your level of objectivity too.
Except it wasn't sidestepped. It was referred to a more appropriate place on the same forum so that the pending question could resume. Your unwillingness to pursue your own question either to vindication or defeat says a lot about your own integrity.
Truth-seekers accept that a proposition may not be true. Truth-seekers don't mind if a certain proposition is proven false, because that defeat serves the interest of truth. Truth-seekers do not hold conclusions that are shown to have no factual or rational merit. Truth-seekers continue testing questions until they are resolved one way or another, or until the relevant data are exhausted.
Truth-seekers do not abruptly shift to a different question as soon as it becomes apparent that their proposition is in trouble. You only seem interested in engendering doubt and suspicion. How would that converge to the truth?
After seeing everybody's response I would say none of you are objective.
Irrelevant. Objectivity is neither expected nor required. You clearly aren't paying attention to any of this debate. Instead you doggedly pursue your "discredit the opponent at all costs" scenario, even though it has already been defused.
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Post by Jason Thompson on Jan 23, 2007 18:04:47 GMT -4
It was a simple question about a simple picture.
No, it was an impossibly open-ended question about a low quality picture, and had nothing whatsoever to do with Apollo. But if you insist I answer it, I can't see anything identifiable in that picture because the quality is simply too low.
I guess everybody was afraid to answer it
No-one was afraid to answer it. Discussion of the question was redirected to a relevant place. I won't discuss 9/11 here because this board is about Apollo. Heaven only knows why you find that hard to grasp.
because they have to agree with the official government version of everything on this site and the official government version is obviously wrong. Well, sidestepping the question says a lot about your level of objectivity too.
Given that you have completely sidestepped the entire discussion, I hardly think you're in a position to preach about objectivity or willingness to discuss issues. If you want to discuss visor reflections then do it here, if you want to discuss 9/11 do it on the relevant part of this forum.
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Post by Grand Lunar on Jan 23, 2007 19:43:15 GMT -4
There's nothing rhetorical about my question. I don't see how anybody can say it's rhetorical with a straight face. And no one said it was rhetorical. The problem was, you asked it in the wrong forum. You were changing the subject from Apollo to 9/11. That's not a good debate tactic. First off, when you pick a topic, stick to it. Don't go off on a tangent. Second, you were told specifically that this is not the place to talk about 9/11. There is a seperate section for such a discussion. Make use of it. You call being asked to take your 9/11 discussion to the appropiate section of the board "sidestepping"? We are mearly sticking to the subject that you started. You are going off on a tangent. You are in no position to criticize. If you take the advice given to you, then you won't be banned. It's a simple request to simply start a new thread in the appropiate section. I believe I already gave such a suggestion; start a new thread in the "Other Conspiracy Theories" section, and get responses from there. Then, come back to this thread when you have the answers you seek. Will that not be sufficent?
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Post by JayUtah on Jan 23, 2007 20:19:55 GMT -4
And no one said it was rhetorical.
I said that posing it the way he did at that time and place was a "rhetorical trap". And it is. Apparently he assumed I must be referring to a rhetorical question to which the answer is obvious and is raised only to make a point. I think he just had a knee-jerk reaction to that word in my assessment of his approach.
Most kinds of rhetorical traps try to introduce some fallacy as a valid line of reasoning, but do so with some sophistry so that by the time the victim realizes a fallacy has occurred he must often backpedal.
David Percy's characteristic rhetorical trap is to lead the reader to the brink of some conclusion, but avoid drawing it at the last minute. Although the reader has been led there and no other avenues have been explored, Percy can evade responsibility by saying, "But we don't draw that conclusion; if the reader does, that's his problem."
Bart Sibrel's characteristic rhetorical trap in face-to-face debate is to raise a question based on some obscure detail or fact. Of course Sibrel had time before the debate to put the question together. But when his opponent can't pull the answer out of some orifice, Sibrel implies that he is not well-enough informed on the subject to challenge Sibrel's claims.
Our David's rhetorical trap here pushes an affirmation of the consequent. The consequent is our unwillingness to discuss his 9/11 question in this thread. The antecedent he begs is that we refuse on the grounds that we can't answer "truthfully" and still remain faithful serfs to our government overlords. Instead we put forth the antecedent that his question is distractionary and off-topic, but would be proper elsewhere.
The "complex question" fallacy is the most common rhetorical trap.
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Post by Joe Durnavich on Jan 23, 2007 22:08:17 GMT -4
The phenomenon of film saturation applies to the reflection question.
One point in favor of the blooming and scatter explanations put forward by gwiz and Jay is to note the size of the hotspot as it moves off of Dave Scott's visor. (I apologize if this has already been noted.) If we were seeing a not-grossly-overexposed studio light, we should see the complete disk of the bright spot move off the visor as Dave turns and walks away. Instead, as soon as the center of the disk of the spot moves off the visor, the disk quickly collapses to a tiny spot.
This suggests to me that gwiz is correct in that the sun's image is quite small in the visor. When this small spot, which is at the center of the disk, moves off the visor, the camera's tube is no longer overloaded and ceases to bloom as Jay has explained. That it takes a few frames for the spot to shrink is consistent with the overcharged area taking a few scans to discharge completely, but perhaps there is some other effect at work here.
I viewed this sequence on the Spacecraft Films DVD of Apollo 15 and not the Real Media version posted earlier.
One thing to keep in mind about the camera tube used on Apollo 15, by the way, is that it is a Silicon Intensifier Target tube, which as I understand it, has some sort of light intensification assembly in front of a vidicon. (Edit: image intensification and not light intensification.)
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