Lens condensation question

Discussion in 'Digital SLR' started by Dave, Jan 13, 2006.

  1. Dave

    Dave Guest

    Hello,

    In the operating manual that came with my Canon 70-200mm f/2.8L IS USM lens,
    there are instructions for bringing the lens from a warm environment to a
    cold environment or visa-versa, which may cause condensation in the lens.

    Has anyone dealt with that?

    The manual says to put the lens in an airtight bag and let it get balanced
    to the temperature change before using.

    Thanks for your advice, tips, etc.
     
    Dave, Jan 13, 2006
    #1
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  2. Dave

    Jer Guest


    If you re-read that booklet, you'll notice it says "from a cold area
    (outside)to a warm area (inside). The bag is a good idea so long as you
    put the lens (and camera) inside the bag BEFORE entering the warm area.
    Using the bag after coming inside is pointless.
     
    Jer, Jan 13, 2006
    #2
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  3. The problem is when going from colder to warmer. The actual
    temperature can be almost anything; hence in Florida it may be a
    problem when you walk *out* of an air conditioned house, and in
    Alaska it would more likely be when you go into a heated
    building.
    Daily. (Current outside temp is -6F/-21C.)
    The bag doesn't actually have to be "airtight" (it definitely
    has to be water proof!), but has to prevent warm air from direct
    contact with the camera until the camera is warmer.

    I suppose the devil is in the details, eh? :)
    The problem is that warm are can hold more moisture than cold
    air. Simply physics.

    If a cold object cools the moist air around it, as the air cools
    past the dew point it necessarily gets rid of the water vapor
    that it can no longer hold at the cooler temperture. So
    condensation forms. It will attach itself to whatever is handy,
    and if your camera is the thing cooling the air, it will be
    covered with moisture from condensation. (Inside as well as
    outside, and that will leave residue, which destroys lenses and
    may be corrosive enough to harm other parts too, given time.)

    The way to keep that from happening is to prevent warm air from
    direct contact with your cold camera (or other equipment).
    Tightly wrapping a camera with plastic prevents contact with
    warm air. The bag does not have to be sealed as such, it just
    needs to prevent air flow.

    I typically keep a few plastic shopping bags in my camera bag,
    and a few in my vehicle too. Anything (camera or otherwise)
    that I want to take from a cold place to a warm place (here that
    is outside to inside, obviously) gets wrapped up in one or two
    plastic shopping bags. I also like to have couple kitchen sized
    trash bags handy, and on occasion have even used 33 gallon
    garbage bags. Typically boxed items don't need to be bagged,
    but the box has to remain closed until the entire contents
    can come up to temperature (which can be a long time if it has
    spent two days out side and is packed in foam!).

    I put lenses, batteries and such items in my camera bag inside
    zip lock bags, mostly because they are clear and I can see what
    is in them.

    As stated, the bag doesn't have to be "sealed", but the idea is
    to prevent air flow. Hence if the bag is not sealed you do not
    want to handle it much. Twisting the end is just fine, or a
    double wrap will do just as well.

    One error that I've seen in more than one webpage trying to
    explain it relates to whether there should be air in the bag or
    not. The *positively* correct answer is no air. Get as much
    air out of the bag as possible. Air is a great insulator, and a
    bag full of air will keep your camera from warming up! And the
    camera can't come out until it is above the temperature that
    will cause condensation, hence air in the bag lengthens the
    wait.
     
    Floyd Davidson, Jan 13, 2006
    #3
  4. Dave

    rawshooter Guest

    I am in Milwaukee and have done it a number of time with that lens -
    mostly bringing it back in the house or car after shooting in the
    winter. I have never put it in a bag. Just set it down on my desk or
    a counter and let it adjust. Once it clears after an hour or so I
    clean it as normal and put it away.
     
    rawshooter, Jan 13, 2006
    #4
  5. Dave

    G.T. Guest

    I've done it without a bag in Mammoth, Calif. when it was 4 degrees F out
    with no problem. The air both inside and out was very dry. I probably
    won't take the chance in the future since I had a bizarre dream the night
    before last that my 70-200 f/4 L was full of condesation.

    Greg
     
    G.T., Jan 13, 2006
    #5
  6. Dave

    C J Southern Guest

    Although, it still works OK if you, say, bring it inside and put it in a bag
    right away - you don't want to wait more than 15 - 30 seconds.

    Helps too to suck the air out of the bag.
     
    C J Southern, Jan 13, 2006
    #6
  7. Dave

    C J Southern Guest

    In theory it still applies the other way around too - if you take a nice
    warm lens with nice warm and moise air inside (trapped inside by virtue of
    the end cap) - small quantities of water vapour will condense on the lens
    internals.
     
    C J Southern, Jan 13, 2006
    #7
  8. Dave

    Peter Guest

    In the operating manual that came with my Canon 70-200mm f/2.8L IS USM
    Wouldn't cold-warm air contrast be a bit of optical problem when going from
    warm to cool? Telescopes have this kind of problem, but then we're talking
    different magnification & focal lenghts there, and it's usually a problem
    with warm mirrors generating air currents and disrupting the view...

    Peter
     
    Peter, Jan 13, 2006
    #8
  9. Low relative humidity helps, but even if you don't see a
    problem, it is still not a good idea. Over time small amounts
    of condensation will each time leave a potentially corrosive
    deposit on internal parts, and a residue on the inner surfaces
    of your lenses. One time may not show any damage, but
    continually adding to it might cost significantly in the long
    run.
     
    Floyd Davidson, Jan 13, 2006
    #9
  10. The biggest trouble with that is you can't get all of the air
    out, and that inside air is loaded with moisture, in the bag.
     
    Floyd Davidson, Jan 13, 2006
    #10
  11. True! I had never thought of that.

    Mostly I've always bagged things before they go outside anyway,
    because the idea isn't so much to use them outside as it is to
    move them to a different location under conditions that will
    involve at least one cold to warm change.
     
    Floyd Davidson, Jan 13, 2006
    #11
  12. Dave

    Jan Böhme Guest

    Umm. But for this, the plastic bag wouldn't help much. If it helps at
    all, it is because it may slow down the temperature changes, not that
    it protects the lens from potentially condensing water vapor, because
    any such would be inside the lens, and thus inside the bag anyway.

    Jan Böhme
     
    Jan Böhme, Jan 13, 2006
    #12
  13. Dave

    eawckyegcy Guest

    Cold air holds less water. When you warm it, the relative humidity
    plummets. For an SLR, just take the lens off the body while outside
    and put caps on everything (or leave the lens on the body if everything
    has been outside for a long time). The lens casing and caps are just
    as good as a plastic bag: by the time any water vapour diffuses in any
    significant amounts, the lens will have warmed up.
    The vapour is pure water, as will be the condensate. Any corrosive
    substances must then already be present in or around the lens.

    Frankly, im my opinion, this whole issue is pointless fretting. If
    anyone wants their lenses to last forever, they should seal them in an
    nickel vessel filled with argon. Put it on display in your living room
    and marvel at it.

    Advice: never buy a lens that you can't comfortably replace.
    Accidents happen.
     
    eawckyegcy, Jan 13, 2006
    #13
  14. Dave

    Beach Bum Guest

    The vapour is pure water, as will be the condensate. Any corrosive
    From what I've read, when fungus grows in the moisture it gives off
    corrosives that can ruin the glass.
     
    Beach Bum, Jan 13, 2006
    #14
  15. Dave

    C J Southern Guest

    It won't make any appreciable difference to the rate of temperature change -
    the bag has a massive surface area and reletively poor insulating qualities.
    Going from warm -> cold isn't a big deal - my comment was more of a theory -
    in reality I doubt that the vapour content would be significant.

    Out of interest, this is the reason why we have water traps and fuel drains
    on aircraft (and the reason we try to leave the aircraft with full tanks
    overnight) - if the tanks aren't full we get a few drops of water condensing
    out of the air in the tank - which over a period of several days can build
    up to significant quantities.
     
    C J Southern, Jan 13, 2006
    #15
  16. No, cold air has a lower *potential* for holding water.
    The difference is significant.
    The actual *amount* of water stays the same. "Relative
    humidity" is just a measure of proximity to the maximum
    potential, not a measure of how much water is in the air.

    In practice that means warm air with low relative humidity
    requires more of a temperature drop to cause condensation, and
    hence there is less likely to be a problem. That's why "Low
    relative humidity helps ..."
    I wouldn't agree with that at all. Moisture will form on all of
    the exposed parts, and anywhere that warm air can go too. The
    condensation from air that leaks into the inside is not good,
    and worse yet is the condensation on all of the exposed
    exterior, and worse that than is whatever moisture from the
    exterior leaks into the inside.

    That is more or less the equivalent of using your camera in the
    rain without protection to keep it from getting wet.

    If the actual amount of water vapor is small you might get away
    with doing it more times than if there is more water vapor. But
    eventually the camera/lense will require cleaning.
    Ever heard of "acid rain"? Whatever pollutants are in the air
    will be in the condensate. Likewise substances on the surfaces
    will indeed be absorbed, and concentrated where the water concentrates.
    That means instead of a light film of whatever it is, there will
    be globs of it in different places.
    Some people take photography, and care of their equipment, a
    great deal more seriously than that.

    Just because a peace of equipment can be "comfortably" replaced
    doesn't mean replacing it twice as often as necessary due to
    purely negligent handling would be acceptable. A policy of due
    dilligence would afford nearly twice as much equipment!

    I would also point out that most of my experience on this topic
    is not with cameras and lenses, but with electronics (and of
    course cameras today commonly *are* "electronics"). Basically
    cameras are 1) more fragile, but 2) less costly. And while you
    might make jokes about filling containers with argon, the fact
    is that shipping containers for some of the equipment I've used
    includes an air tight seal and a nozzles to replace the air in
    the container with an appropriate gas of choice. Shipping
    $50,000 test equipment items from place to place *is* significant.
     
    Floyd Davidson, Jan 13, 2006
    #16
  17. And it is not pure water anyway.
     
    Floyd Davidson, Jan 13, 2006
    #17
  18. Dave

    Sheldon Guest

    I live at a ski resort, and much has to do with both temperature and
    humidity. When I walk inside my glasses fog up, too, but mostly because of
    the humidity around my eyes. I guess you have to ask yourself how often you
    bring your camera inside and have to shoot immediately. Your lens is far
    from sealed, and it doesn't take that long to for the moisture to evaporate.
    I don't do anything special.
     
    Sheldon, Jan 14, 2006
    #18
  19. Dave

    Celcius Guest

    Jer,

    I'm going south in a few weeks.
    Does this hold if I'm in an air conditioned room, going outside to take
    some photos?
    How about coming back in?

    Thanks,

    Marcel
     
    Celcius, Jan 14, 2006
    #19
  20. In locations where the humidity is high, yes.
    The problem is going from cold to warm/moist.
     
    Floyd Davidson, Jan 14, 2006
    #20
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