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Thread: A Disturbing Revelation of Digital Imagers

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    Steaphany's Avatar
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    A Disturbing Revelation of Digital Imagers

    Since I shoot both digital and film, I was reviewing the videos of the KodakShootFilm channel on youtube and found this one where Rob Hummel at Cine Gear Expo 2011, while describing the differences between film and digital imaging technologies, mentioned a secret of the camera manufacturers where radiation from space can damage a digital imager while the camera is being transported by air.

    Has anyone seen any effects as described after air travel with your prized camera or express shipping it for servicing ?

    Watch until 8:00 to 10:15 to see what Rob has to say:


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    Re: A Disturbing Revelation of Digital Imagers

    Hi Steaphany,

    Hummel should have apparently left that tidbit out of his presentation, as he was quite
    incorrect about the levels of gamma rays that aircraft receive, as well as how much is
    required to harm a human, or CMOS sensor.

    http://www.consumertraveler.com/colu...camera-sensors

    The study referenced is at:

    http://web.mst.edu/~umrr/cf086.pdf

    Unfortunately, the study noted is written in Physics, a language I don't speak..but know
    that you do!......

    BTW, the Hubble telescope also has a few CMOS sensors, and back in the 1980's when
    Lockheed was developing the scope my late father was one of the lead RF/EMI shielding
    engineers on the project. I know at one point he had a major beef with management about
    the limited shielding in one area, and he strongly cautioned that, if left as it was, the chances
    for catastrophic failure were high. He was proven right, unfortunately, and it cost Lockheed
    quite a bit to correct.

    I can also imagine how many cell phone cameras and other devices containing CMOS technology
    would be affected. From what I understand of the study, it would require a substantially higher
    level of gamma radiation in order to damage those devices ..no matter if at 40,000', or sea level.

    Mike
    Last edited by Dizzy; 6th September 2011 at 03:39 AM.

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    Re: A Disturbing Revelation of Digital Imagers

    Well, seems mr. Hummel made a slight mistake in comparing doses: sensors needed 600 Gy for damage, airplanes provide in the order of 0.3 mGy/year to their personnel. , so a pilot would need to carry a camera for 2000 year to get the damage shown in the article (the pilot would show deterioration well before the camera...).

    For comparison:
    - the maximum yearly dose allowed for any member of the public is 1 mSv/yr over the natural background (and not counting doses for medical purposes);
    - natural background is about 1-3 mSv/yr;
    - medical doses for diagnosis are < 50 mSv; and
    - medical doses for treatment of cancers are ≈ 50 Sv
    (keeping in mind that for gamma radiation, 1 Gy = 1 Sv)

    Note that all this is for gamma (electro-magnetic) radiation. Particle radiation (alpha and beta) is a different story, it tends to do more damage due to its nature, but is easier to shield (alpha: a sheet of paper, beta: 1 cm of acrylic are enough for the more common energies, the multiple cm of lead are for gammas).
    Last edited by revi; 6th September 2011 at 05:52 AM.

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    Re: A Disturbing Revelation of Digital Imagers

    Mike,

    I agree with your points, especially that many people have a nearly irrational fear of radiation exposure. ( I've always considered a funny joke would be giving someone who does not comprehend atomic physics a Geiger counter and tell them to explore their home ) If you note, Hummel's statement of the thickness of concrete that he believed necessary to shield an aircraft did not make sense, especially when you consider the matter comprising the lower 20,000 feet of the atmosphere which supposedly is sufficient shielding.

    If you note my original question, I asked if anyone experienced their camera having row or photosite damage after air travel. I did find it strange how cinematographic grade cameras "supposedly" experienced significant sensor failures after being air shipped around the world.

    Thank you for the two article links. The first which references the same video mentioned that Hummel words have garnered a fair bit of attention, but I hadn't seen anything of this until stumbling across the video.

    As for space based imagers, I recommend checking the online videos from the SOHO cameras which experience a particle storm of transient yet non-damaging particle noise as an Earth bound CME arrives at the probe. I also have the book "The Handbook of Astronomical Image Processing" by Richard Berry and James Burnell which in the chapter "Counting Photons" delves into imager performance mentioning radiation induced noise but did not describe any risk of permanent imager damage.

    I also agree that it was a pointless tangent that Hummel should have never brought up.

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    Re: A Disturbing Revelation of Digital Imagers

    Quote Originally Posted by Steaphany View Post
    Mike,
    If you note my original question, I asked if anyone experienced their camera having row or photosite damage after air travel. I did find it strange how cinematographic grade cameras "supposedly" experienced significant sensor failures after being air shipped around the world.
    ...
    IMHO, the reason for shipping cameras by boat is simple economics: boat is a lot cheaper per item than aircraft, esp. for non-perishable items (although I'm not always sure camera aren't classed as perishable by the manufacturers, given the speed with which they produce new models )

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    Re: A Disturbing Revelation of Digital Imagers

    Nothing very scientific to add, but I remember on the occasion of my one any only over-seas trip many years ago, how I took my prized "digital diary" with me. It was working flawlessly before the flight, but 4 hours later, had badly corrupt memory (and we didn't have backups in those days!).

    I always wondered if it was something to do with the X-Rays or some kind of radiation experienced in the flight that caused it.

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    Re: A Disturbing Revelation of Digital Imagers

    Quote Originally Posted by Colin Southern View Post
    I always wondered if it was something to do with the X-Rays or some kind of radiation experienced in the flight that caused it.
    Colin,

    One of the very first methods to erase re-programmable memory chips was X-ray exposure. ( This comes from personal knowledge of the technology way back at the early days of microprocessors ) This was quickly replaced by the devices having a window on the package where Ultraviolet light would be exposed to the chip for erasure, but any X-ray exposure would still have the effect of erasing the stored data. To achieve a complete wipe of the chip, the chip needed to achieve a specific level of exposure, less would only partially erase the data and in most occasions the desire was to erase everything so that the device could be reprogrammed from scratch. Partial erasure of "some" of the stored data, especially if the device stored the operating software, would render it non-functional, as you described. Remember that the exposure is accumulative.

    Either you just happened to run into a bit of bad luck and the digital diary just happened to die after the flight or the security X-Ray exposure effected the memory and corrupted the contents. The high altitude exposure during the flight was probably insignificant.

    My policy has always been, and I feel everyone should abide by, is that when traveling through security checks, DO NOT HAVE ELECTRONIC DEVICES X-RAYED. If the technology is X-ray safe, it's over kill, but how many electronic designers test their designs to handle X-Ray exposure ? ( Only MOD/DOD military and space based electronics have radiation exposure survival specifications ) If your device is vulnerable to the effects of X-Ray exposure, this practice can keep it safe. During the 7 years of my career where I was traveling every week, I never had any camera or computer die.
    Last edited by Steaphany; 6th September 2011 at 01:20 PM.

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    Re: A Disturbing Revelation of Digital Imagers

    Hi Steaphany,

    Thanks for that.

    I remember those chips with the little window (feeling old now!).

    I've only travelled domestically since then, but no othe probs with security -- so who knows. I've been quite amazed by modern x-ray technology at airports though -- I always thought they were basically a moving version of the medical ones we're used to seeing - but was quite amased to see that they now colour-code items of different density.

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