Bob B.
Bob the Excel Guru?
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Post by Bob B. on Sept 30, 2005 15:36:08 GMT -4
I'm going to change the subject slightly and ask a question about a somewhat related issue. One of the conspiracy woo-woos claims the Hasselblad camera casing would melt in the pure oxygen environment of the spacecraft. (I believe Cosmic Dave claims this, though he may not be the original source.) Can anyone explain what the origin of this piece of nonsense is?
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Post by JayUtah on Sept 30, 2005 17:50:35 GMT -4
The claim traces its way back to several retellings and reformulations of the fear that the leatherette covers normally put on Hasselblad bodies would outgas in a vacuum. Which they probably would.
The coating on the Hasselblad lunar surface cameras is almost indistinguishable from the thermal coatings on the classic Thermos bottle.
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Bob B.
Bob the Excel Guru?
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Post by Bob B. on Sept 30, 2005 18:23:29 GMT -4
The claim traces its way back to several retellings and reformulations of the fear that the leatherette covers normally put on Hasselblad bodies would outgas in a vacuum. Which they probably would. The coating on the Hasselblad lunar surface cameras is almost indistinguishable from the thermal coatings on the classic Thermos bottle. Thanks, Jay. Many of these hoax claims seem to start out as some obscure fact that, through several generations of retelling, eventually morph their way into the abominations we see today.
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Post by JayUtah on Sept 30, 2005 20:50:11 GMT -4
That happens even with the best of intentions. It's very hard to keep history from degrading with the retelling. Of course it doesn't help when people intentionally co-opt it for their own purposes, but it's hard to get everything right all the time. If you watch much "geek" TV, you know Dr. Roger McCarthy www.engin.umich.edu/alumni/engineer/05S/alumni/madeadifference/who happens to be someone I admire. Not just because he's a fellow Wolverine, but because he deals in failure analysis -- something that interests me too -- and has that uncanny talent to grasp complex issues and explain them succinctly and clearly. His credentials are absolutely impeccable. Yet today I had to scream when he propounded the erroneous "pendulum theory" of rocket stability on a television program. Even the best of experts is not immune to error or misrepresentation.
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Bob B.
Bob the Excel Guru?
Posts: 3,072
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Post by Bob B. on Sept 30, 2005 22:05:29 GMT -4
I believe most people at least try to retell the story accurately, but I don't think this is true of the conspiracy theorists. They simply retell the parts that appear help their cause while omitting the parts that hurts them. In many cases the deception is intentional (e.g. Bart Sibrel), but at other times I think it is done subconsciously. When people with a specific agenda pass on only part of the story each time, it doesn't take too many retellings to really bastardize it.
I'm not real sure what you mean by "geek" TV. I watch a lot of programming on the educational channels like History and Discovery. In fact, I saw the particular program in which Dr. McCarthy incorrectly described a rocket as an "inverted pendulum".
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Post by PhantomWolf on Sept 30, 2005 22:23:27 GMT -4
Heh, I'm finding this in writing my webpage about the history of Apollo. I thought I knew things because I'd read them or seen them or heard the story, but each time I have written up a section I've had to rip it apart and rewrite it, not only to get my biases out of the way and to tell the story genuinely, but to remove the errors that I had always believed. An example of this is that I had thought that von Braun's team only got the chance to launch their satellite because of the Vangaurd's failure, however this isn't true. They had originally been told that they weren't allowed to launch at all, then that they could prepare a backup launch, but that it'd be scrubbed if Vangaurd succeeded, but then the Head of ABMA, Major General Medaris, von Braun and the director of JPL, Wiliam Pickering (who by the way was a Kiwi. ) all demanded the right to launch regardless or they'd resign. It was a threat that worked, and they were finally given permission. In the end I actually think the real history is a little more interesting.
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Bob B.
Bob the Excel Guru?
Posts: 3,072
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Post by Bob B. on Oct 1, 2005 20:55:37 GMT -4
You're a good example, PhantomWolf, of a competent historian trying very hard to get the facts of the story correct. If you were an HB you'd be looking for a way to skew the story so it appears to support the version of history you are trying to tell. The latter case is not very conducive to getting the facts straight.
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Post by spirit on Oct 4, 2005 5:25:12 GMT -4
Hey, that only took 6 minutes! Yeah! Thanx!
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Post by PhantomWolf on Oct 4, 2005 5:58:59 GMT -4
hehe, we're pretty slick about these parts, neighbour.
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Post by dwight on Oct 18, 2005 5:11:09 GMT -4
They could see the area on the TV camera. Oh right. So the TV camera could judge the light levels? Actually the output of an analog video camera is 1 Volt . That means when the camera is targeting, say a sheet of uniformly lit black velvet, the resultant luminance voltage is 0 Volts. When it is pointing at a plain white sheet of paper, the peak output is 1 Volt. Knowing this, one can extrapolate the F-stop setting. F-stops for video cameras and stills cameras are easily correlated for correct F-stop values between the two. The frame rate of the video camera becomes the shutter speed, and there you have your light meter reading. Don't believe me? Well, when publicity photographers visit a TV set, and aren't permitted to use flash photography, they simply can get a Lux value from the lighting director, figure out the F-stops from the TV cameras, set their stills camera, and have correctly exposed photos. It happens world-wide on a daily basis. Furthernore, the contrast ratio of an analog video camera is roughly 20:1. (The rule of thumb in the industry is shoot outdoor scenes on an overcast day) Film has an expontially higher contrast ratio. Thus there is considerable room for error in exposing a shot in a film camera using a video cameras f-stop as a template. Luminance is not dependant on resolution. In theory a one pixel video camera is good enough to use as a light meter. The important thing in setting exposure is the differences in luminance between the darkest and lightest object in frame. How in focus they are has abolutely no bearing on setting exposure. One last important aspect is that the Apollo 11 archive TV downlink is kinescoped. This has inherent lossy image quality. Without question, the live video feed was clearer and (lo and behold) had a higher contrast ration than what you are accustomed to seeing. Apollo wasn't the only thing being kinescoped in those days. For example, If you happen to watch the Kid's tv show Bugaloos made in 1970, it was shot on video, but archived as kinescope. Cheerio, Dwight RTL TX
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Post by ShowCon on Oct 18, 2005 10:57:12 GMT -4
Were any measurements taken of how hot/cold the film actually got? Would be interesting to see how closely the theory came to the reality.
Doug
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Post by JayUtah on Oct 18, 2005 12:09:36 GMT -4
The rule of thumb in the industry is shoot outdoor scenes on an overcast day...
Or if not possible, use reflectors for fill or large screens for shade -- all expensive and time-consuming setups.
Apollo wasn't the only thing being kinescoped in those days. For example, If you happen to watch the Kid's tv show Bugaloos made in 1970, it was shot on video, but archived as kinescope.
I wonder why. Which is to say, I don't wonder why it was archived as kinescope; I wonder why it was archived at all.
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Post by JayUtah on Oct 18, 2005 12:12:53 GMT -4
Were any measurements taken of how hot/cold the film actually got?
No; the cameras were not instrumented with any kind of thermometer.
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Post by echnaton on Oct 18, 2005 12:57:11 GMT -4
Were any measurements taken of how hot/cold the film actually got?No; the cameras were not instrumented with any kind of thermometer. Is it possible to infer a temperature range from the way the film reacted to light?
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Post by moonglow on Oct 18, 2005 16:20:58 GMT -4
Did you mean focal length or focus setting?
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