|
Post by PhantomWolf on Feb 14, 2006 5:55:47 GMT -4
I think several reflections in the multi-layer visor/helmet rather than a lens flare. Anyone agree?
From my understanding of the helmet construction and optics related to such, yes.
|
|
|
Post by Kiwi on Feb 14, 2006 6:38:48 GMT -4
HB's have often demanded wonderfully hi-res satellite photos of the descent stages and rovers on the lunar surface, but one thing that I've mentioned before seems to have escaped them because of their ignorance of photography: Camera movement. An orbiting satellite may indeed have the ability to resolve the required detail, but could it actually freeze the scene? I haven't investigated this thoroughly, so have doubts. Note in the article that Pettit had to devise a tracking device so that he could photograph cities at night without them being blurred.
|
|
|
Post by gwiz on Feb 14, 2006 7:29:19 GMT -4
An orbiting satellite may indeed have the ability to resolve the required detail, but could it actually freeze the scene? I haven't investigated this thoroughly, so have doubts. I believe both the Lunar Orbiters and the Corona reconnaissance satellites had a velocity/height correction system. I can't remember the details, possibly moving the film relative to the lens as the exposure was made, but it's certainly possible.
|
|
|
Post by Count Zero on Feb 14, 2006 7:35:58 GMT -4
IIRC, low lunar orbit speed is ~3,000 miles per hour - compaable to an SR-71 (which would also be at a comparable altitude).
|
|
|
Post by 3onthetree on Feb 14, 2006 7:45:56 GMT -4
I found another link to that nice photo of the Aurora. www.egr.up.edu/contrib/lulay/Who knows what they can see from above. You just gotta be careful what you do in the pool.
|
|
Bob B.
Bob the Excel Guru?
Posts: 3,072
|
Post by Bob B. on Feb 14, 2006 9:28:16 GMT -4
There are a lot of photographs of aurora from space that show stars. Here is one I have on my Web page: This is a 4-second exposure and already we are seeing streaking in the star images.
|
|
|
Post by sts60 on Feb 14, 2006 10:11:16 GMT -4
An orbiting satellite may indeed have the ability to resolve the required detail, but could it actually freeze the scene? I haven't investigated this thoroughly, so have doubts. I believe both the Lunar Orbiters and the Corona reconnaissance satellites had a velocity/height correction system. I can't remember the details, possibly moving the film relative to the lens as the exposure was made, but it's certainly possible. There are different ways to do it, but commercial imaging satellites (I worked on the ground segment for a couple) typically use a "push-broom" approach where a line imager (using a linear array of detector elements) is scanned along a swath of ground. You can also use a more typical CCD array, sometimes known as a "starer". In any case, you have to compensate for the rapid motion from low orbit. I don't know how the early spy satellites did it.
|
|
|
Post by PhantomWolf on Feb 14, 2006 10:17:43 GMT -4
I found another link to that nice photo of the Aurora
Cool, that's more like what I expected to see, though I'd note that there are still only a few stars, so the exposure time can't have been long. Looking at the one Bob posted you can se that a exposure of a number of secs starts to show up more stars.
|
|
|
Post by JayUtah on Feb 14, 2006 10:23:27 GMT -4
I think several reflections in the multi-layer visor/helmet rather than a lens flare. Anyone agree?
That's certainly possible.
|
|
|
Post by bughead on Feb 14, 2006 10:31:49 GMT -4
I believe both the Lunar Orbiters and the Corona reconnaissance satellites had a velocity/height correction system. I can't remember the details, possibly moving the film relative to the lens as the exposure was made, but it's certainly possible. There are different ways to do it, but commercial imaging satellites (I worked on the ground segment for a couple) typically use a "push-broom" approach where a line imager (using a linear array of detector elements) is scanned along a swath of ground. You can also use a more typical CCD array, sometimes known as a "starer". In any case, you have to compensate for the rapid motion from low orbit. I don't know how the early spy satellites did it. I was at RAF Mildenhall (UK) in the late 80's. We had an SR-71 on base. I was told by a guy who's job was to load and unload the magazines for the camera (not install it in the plane, not develop the film, not see any imagery, JUST load and unload the film. Dividing up the "need to know" and all that) and he told me the film was, basically, IMAX film, and the film was hauled passed a slit-opening,like a long "pinhole," really fast.
|
|
|
Post by JayUtah on Feb 14, 2006 10:57:33 GMT -4
The KH-4 spacecraft used a slit-scan panoramic imaging system, but the scans were transverse to the ground track. Slit-scanning was not used to compensate for vehicle motion.
The standard module five-inch camera systems would be about 120 millimeters, or about twice as wide as the 70mm IMAX format, and I've seen camera systems for the SR-71 that use Estar-based film that looked about ten inches wide. My understanding is that the SR-71 can carry a variety of camera packages. My friend, whose son takes photography lessons from me, collects antique surveillance imaging systems. The biggest one he's got uses a whopping 24x30 inch negative. Neither of us has any idea where the heck it came from.
|
|
|
Post by sts60 on Feb 14, 2006 11:03:34 GMT -4
One assumes that's a plate and not part of a roll...?
|
|
|
Post by gwiz on Feb 14, 2006 11:37:00 GMT -4
I believe both the Lunar Orbiters and the Corona reconnaissance satellites had a velocity/height correction system. I can't remember the details, possibly moving the film relative to the lens as the exposure was made, but it's certainly possible. Further googling has revealed that the Lunar Orbiters had a system that moved the film platen during exposure, while the Coronas nodded the entire camera in the opposite direction to flight, while simultaneously doing the panoramic scan at right angles to the direction of flight.
|
|
lenbrazil
Saturn
Now there's a man with an open mind - you can feel the breeze from here!
Posts: 1,045
|
Post by lenbrazil on Feb 14, 2006 16:04:33 GMT -4
I received a little physics degree some twenty years ago.and I have an equivalent to a US bachelor's degree in physics plus some more qualifications in that subject i.e. almost a master's degree.and I have a physics degree from a well known university ... it is equivalent (even more) than a US bachelor of science.Why don't you spend some time coming up with a consistent fantasy, then try again? edited to add first quote Ever been on a farm, don't you recognize that stink of a giant heap of bulls#it !! Prove me wrong and make a fool of me, Tell us What degree you got from which university in what year and in what subject, then tell us about those other "qualifications". Do you really think you are fooling anyone? Admit you lied and get it over with.
|
|
|
Post by JayUtah on Feb 14, 2006 17:43:10 GMT -4
I knew you had a sense of humor beneath that gruff exterior, Jay.
Actually that's much closer to the real me than anything else I have written.
|
|