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Sensor burn questions and science?

Discussion in 'Open Discussion' started by zulfur666, Feb 7, 2014.

  1. zulfur666

    zulfur666 Mu-43 Veteran

    254
    Jan 30, 2014
    I always wondered about our mirrorless cameras since the shutter is always open. When you turn off the camera with a lens mounted, what happens? Does it stay at the last aperture setting or does it go to the smallest hence f/22 to avoid light damaging the sensor in case you forget your lens cap?
    Can the sensor get "burned" when the camera is off, you are walking around camera strapped around your neck or shoulder and sometimes the lens catches the sunlight?
    Just wondering is there a safety precaution?
     
  2. jyc860923

    jyc860923 Mu-43 Hall of Famer

    Feb 28, 2012
    Shenyang, China
    贾一川
    I believe it's wide open when you power off the lens, and yes there's no protection from sunlight burning the sensor if you just walk around like that, but I don't see any sign of damage caused by that, is it because we are using CMOS instead of CCD these days, or is it not a problem with whichever sensor type at all?
     
  3. yakky

    yakky Mu-43 Top Veteran

    662
    Jul 1, 2013
    Security cameras seem to do just fine with either CCD or CMOS.
     
  4. pdk42

    pdk42 One of the "Eh?" team

    Jan 11, 2013
    Leamington Spa, UK
    That's an interesting question... I'm guessing that UV (esp UV-B and C) is probably filtered quite substantially by the lens. However, focusing the sun onto an area the size of a pinhead (which must be more-or-less the size of its image cast on the sensor) must cause heating, if only from the visible and IR wavelengths.

    Worth some more thinking/research I think...
     
  5. orfeo

    orfeo Mu-43 Top Veteran

    673
    Sep 27, 2013
    FR
    Silice sensor/glass/modern plastic won't burn like the good onld clothe shutter in leica ltm and leica M!!!
     
  6. pdk42

    pdk42 One of the "Eh?" team

    Jan 11, 2013
    Leamington Spa, UK
    Yes, it seems this is the case. I did some reading and found this:

    "... in CCD and CMOS sensors ... The materials are relatively inert. The basic mechanism of heat-mitigated damage to CCD and CMOS devices is through recrystallization. Looking at materials tables, I gather that temperatures around 1,000 degrees C, sustained for some minutes or possibly hours, is required to recrystallize these sensors."

    Can't say that the reference is necessarily reliable, but it sounds like it's not the same story of burning holes in fabric shutters. There certainly don't seem to be any people posting of sensor damage via this mechanism. However, I think I'll play safe and put the lens cap on if placing the camera down on a table outside.
     
  7. Rudy

    Rudy Mu-43 Veteran

    449
    Jan 24, 2013
    Oakland, CA
    The problem, if there was any, would be with the color filter array.
    They are made from organic material and would be the first ones to "feel the heat."
    Rudy