Pixel Still Stuck
Published : 11th February 2005
Just got word from Steve Mahrer at Panasonic that flying any CCD camera exposes it to the ravages of cosmic rays to the tune of several hundred GeV.
Steve suggests always travelling with a copy of the procedure to fix a stuck pixel, and I¹ll make it a point to do so in the future.
I guess I¹ve been lucky not to have taken a hit, but I wonder if the commercially available lead photo bags could be put around the camera body to protect the CCD¹s on flights.
Does anyone out there have an idea about this? How effective are the photo bags? In the brave new world of airport security will a lead bad lead to a strip-search?
However, I guess if cosmic rays can penetrate the earth, a lead bag wouldn¹t do much good!!!
Best regards to all,
>However, I guess if cosmic rays can penetrate the earth, a lead bag >wouldn’t do much good!!!
But if 35,000 feet of air does the trick, then lead might work too...
Very little you can do for a cosmic ray other than carefully placed magnets around your CCD. In fact this might be your best bet. It only takes a very small magnetic field to deflect these particles. More than 80 of cosmic rays are hydrogen nuclei and most of the others are helium nuclei.
They come not as much from our sun but from supernova explosions and the like way out there in places we can't see. Some are real bad boys as the heavy ones are massive atomic nuclei such as nickel and zinc. Yes they pass easily through you and the earth but most are deflected/and or dissipated when they enter the area around the earth hitting other particles. In fact, one of the reasons why we do not know where they come from is that the interstellar magnetic field prevents cosmic rays from reaching the earth directly so their paths here can't be plotted. In astronomy we actually use CCDs to measure cosmic ray particle counts.
If you took a piece of fabric and mounted magnets to it all in the same direction of pole and placed them on either side of your camera, you might be better off than flying in an airplane alone. No guarantee, but definitely has an effect on these particles. The higher you go and the more you go in airplanes the better the odds you are going to start to loose pixels.
Perhaps if enough folks are interested, I'll manufacturer one.
Producer, Director, Creative Director, Cinematographer
BlueSky Sports and Entertainment Marketing, LLC
HellGate Pictures, Inc.
I just talked to a couple of knowledgeable guys around here and we don't have a sure fire solution yet for our HD cams that are on orbit. We currently see a fairly short life expectancy.
Currently our best protection is to store the cameras between water bags on the station. This seems to help a bit. We store film between the station's batteries, but there is not enough room to get a camera body in there. Also, I have it on good authority that Liquid Hydrogen is an effective blocker. But none of this helps your situation with regards to flying in aircraft.
I offer it just for general knowledge.
>We currently see a fairly short life expectancy.
Hence why Hubble optics were already replaced.
>Currently our best protection is to store the cameras between water >bags on the station.
Hydrogen molecules in water and since most cosmic rays are hydrogen protons...
>Also, I have it on good authority that Liquid Hydrogen is an effective >blocker.
More hydrogen molecules tightly packed together. Works even better to stop molecules. But not all the molecules, especially the heavy metals I'd imagine.
>But none of this helps your situation with regards to flying in aircraft. I >offer it just for general knowledge.
As in not a cosmic ray of light?
Producer, Director, Creative Director, Cinematographer
Walter Graff writes :
>If you took a piece of fabric and mounted magnets to it all in the same >direction of pole and placed them on either side of your camera, you >might be better off than flying in an airplane alone.
Fabric sheets with embedded magnets are already available from some medical supply sources, for use in magnetic therapy (mainly for joint healing). Whether those magnets are strong enough to divert high-energy particles is a separate question. (Or will they just as often divert particles right into your CCDs?)
Marin County, CA
>I just talked to a couple of knowledgeable guys around here and we >don't have a sure fire solution yet for our HD cams that are on orbit. We >currently see a fairly short life expectancy.
I remember finding a NASA website last time this issue came up a couple of years back...they flew an HD camera with the specific intent of seeing how the CCD was damaged - as I recall it was something like 50 pixels a day.
The website didn't have any conclusions posted - I've certainly lost the bookmark by now. The preliminary results that were posted weren't even certain of which particles were causing the pixel loss - I think Alpha and Gamma were the primary suspects.
After a conversation with an astronomy student friend, (apparently my knowledge of Hawking radiation is sadly lacking, but I now have a reading list...) it struck me that the CCDs on Hubble must be protected somehow... or there'd be a lot of extra "stars" in its images!
Does anyone know what they do on the orbiting observatories?
Director/DP, Downstream Pictures
George Hupka wrote :
>Does anyone know what they do on the orbiting observatories?
Most of them are going to CMOS sensors, which don't have the same problems re gamma rays that CCDs do. Modern CMOS sensors are as good or better than CCDs...
Jeff "OEM buyer" Kreines
Jeff Kreines wrote :
>Modern CMOS sensors are as good or better than CCDs...
Hmmmm...All scientific research that I am aware of would disagree with the "better" part of your statement and most with the "are as good" part.
At least at the level that this list address’s.
Michael "always ready to learn more" Bravin
Band Pro Film & Digital
>Modern CMOS sensors are as good or better than CCDs...All scientific >research that I am aware of would disagree
Consumer-grade CMOS has a ways to go yet. I know of CMOS imagers that perform quite well, but these off-Earth applications where CMOS has some real advantages.
eCinema Systems, Inc.
Michael Bravin wrote :
>>All scientific research that I am aware of would disagree with the "better" >part of your statement and most with the "are as good" part.
>>At least at the level that this list address's.
Ah, but that's older research.
There have been great advances in CMOS technology, by FillFactory, Rockwell Scientific, and others.
Wider dynamic range and less noise than current CCDs. Interestingly, Kodak's new high-end digital still camera uses not Kodak CCDs, but a FillFactory CMOS device designed by Kodak. Then again, it shouldn't be an either-or situation. An ideal camera might permit you to choose your sensor and resolution as required -- CCD or CMOS, color or monochrome/infrared, etc.
You know, like a film camera does...
Jeff "dreaming out loud" Kreines