Re: Lens condensation question

"Dave" <catx@xxxxxxxxxxx> wrote:
>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.

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.

>Has anyone dealt with that?

Daily. (Current outside temp is -6F/-21C.)

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

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? :-)

>Thanks for your advice, tips, etc.

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 L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska) floyd@xxxxxxxxxx
.

Relevant Pages

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