Working in cold weather presents problems for both photographers and their equipment.
Though some photographers used to more tropical climates might think freezing (32 degrees F or
0 degrees C) is cold, neither the photographer or their gear should really experience any
problems at that temperature. Just about all cameras, lenses and batteries are rated for
use down to freezing (32 degrees F, 0 degrees C). However at lower temperatures there are a few things
that may cause problems.
 Most cold weather work will probably be done in the range from freezing down to 0 degrees F
(-18 degrees C) since not too many places get much colder than that for more than a few days a
year. However there are places that get down to the -40 degrees degree level (and -40 degrees F is the
same as -40 degrees C). As I'm writing this in early January, the temperature in Fairbanks,
Alaska is -31 degrees F/-35 degrees C, while the South Pole is at a relatively balmy
-18 degrees F/-28 degrees C. If it gets below -40 degrees , I'd seriously think about staying indoors! Note
also that "wind chill" factors don't apply to cameras, only to people.
Though most digital cameras are specified by their manufacturer only for operation down
to a temperature of 0 degrees C (32 degrees F), most will work perfectly well at much lower
temperatures. They aren't rated for lower temperature work because they aren't tested to
fully meet all specifications at those temperatures and because there are some problems
that can occur as detailed below 0 degrees C but most of those problems can be avoided. Electronics
actually often work better at lower temperatures, so there's really no issue with the
electronic circuitry.
The problems which may arise in very cold weather are usually either
mechanical, related to LCD displays or related to battery issues. At just what
temperature problems occur depends on the exact design of the equipment, but most modern
cameras and lenses are just fine at -20 degrees C and can even be used down to -40 degrees C with a
little care and attention.
Cameras and Lenses
Older mechanical cameras and lenses needed to be "winterized" for use at
low temperatures. This involved taking them apart and removing the heavy lubricants
from their mechanical parts. This was either replaced with a very low viscosity lubricant
or no lubricant at all. Before they could be used again at normal temperatures, they had
to be taken apart again and the lubricants replaced! Not very convenient and thankfully
not necessary on today's cameras.
Modern autofocus cameras and lenses don't typically use much internal lubrication, and
certainly not the viscous grease and oil used with earlier fully mechanical designs.
Consequently they don't need any special winterizing for operation at low
temperature.
Cold Soaking
During operation, digital cameras actually generate their own heat. With some early
digital cameras, after continuous operation for a while the batteries became almost to hot
to touch! Modern cameras are significantly more efficient and generate less heat, but if
you can keep that heat in the camera (by not cold soaking it), you may have fewer cold
weather related problems.
Cold soaking is leaving a camera out in the cold until every part is at ambient
temperature - and it's likely to increase the probability of cold related problems. Since
it can take quite a while for a camera to fully cool, if you only expose your camera to
the very coldest temperatures when you're shooting, and put it in a pocket or a camera bag
when it's not in use, you'll likely have fewer problems then if you leave it permanently
hanging around your neck, fully exposed to the cold. It may not be that much warmer in
your pocket or your camera bag but every little helps. See also the section "Hand
Warmers," below.
One thing to avoid though is bringing a really cold camera under your coat,
especially if you've been sweating and the air trapped under your coat is very humid. This
can happen even in very cold weather if you have a highly insulating coat and you've been
working hard, for example by walking though deep snow. A cold camera/lens in a humid
environment can results in condensation of moisture on both the optics and electronics,
which is something best avoided. (See also "coming in from the cold" below).
Film
There are two problems which relate to the use of film at low temperature. The first is
that at very low temperatures film can become brittle. If you bend it too much it may
actually snap, so loading a camera needs care. The second problem is related to the very
low humidity of cold air. The dry air allows static electricity to build up on the film
surface; this can be a problem during rewind. You can actually get a static discharge (sparks)
inside the camera which leaves marks on the film. The slower you wind and rewind the less
likely you are to run into problems from either brittle film or static discharge. Of
course on many modern cameras, you have no choice about winding or rewinding speed, so
there's not much you can do about it.
Memory Cards
There are very few reports of memory cards having problems in low temperatures. There
are some industrial cards which are fully tested and specified for continuous use at
temperatures down to -40 degrees C, but it seems that it's really not essential to use such
cards. The Sandisk Extreme cards are specified for use down to -25 degrees C but even they are
probably not required. Most users seem to find that even at the lowest temperatures most
memory cards perform without problems.
I'd be a little wary of compact flash microdrives
at low temperatures since they are mechanical devices and are more likely to have cold
related problems.
LCDs
 LCDs (Liquid Crystal Displays) are affected by low temperatures. They may lose contrast
(grey out), change the displayed information more slowly, and become quite
sensitive to touch (if you press on them they may change color). This is reversible--
once they warm up, they should be fine.
Plastics
At normal temperatures plastics are...well...plastic. The will bend a little and some
mechanisms depend on that (e.g. plastic hinges and catches). At very low temperatures
plastics may become quite brittle and will break before they bend. This means you need to
be quite careful when opening any plastic camera doors (for example: battery compartment
doors) to avoid accidental damage.
Beware of Metal
Touching bare metal at sub-freezing temperatures with bare hands can be quite a painful
experience. Moisture on your hands can freeze and "glue" you to the metal
surface! Since most modern cameras are either plastic or plastic-covered, this isn't too
much of a problem when handing cameras, but touching bare metal tripod legs with ungloved
hands can be a problem. You can get insulating sleeves for tripod legs (or you can use
pipe insulation) and if you use a carbon fiber tripod you'll also be safe. If you need
more dexterity than you get wearing heavy gloves, to wear thin silk
glove liners at low temperatures--don't use your bare hands!
Battery Power
Batteries lose a lot of their power at low temperature. This applies to all batteries
but some do better in low temperatures than others. The best cold performance probably
comes from primary (i.e. non-rechargeable) Li cells, followed by NiCd, NiMH and Li-ion
rechargables. They should all be fine down to -20 degrees C, though they will certainly have a
lower capacity than they do at higher temperatures. Most will work for a while at even
lower temperatures. If they get really cold and become exhausted they will usually regain
power if warmed back up, so take 2 or 3 (if not more) batteries out in the field with you
and switch them between your camera and a warm pocket and you should be OK.
For some
camera systems an external battery pack is available which connects to the camera via a
cable. This means you can keep the batteries warm under your jacket, but the cable between
the battery pack and the camera can be inconvenient. Note that alkaline batteries and
particularly rechargable alkaline batteries tend not to perform
well in very cold conditions and so should probably be avoided.
Hand Warmers
One way to keep your batteries warm is to wrap a small hand warmer around
the section of the camera that contains the batteries (usually the handgrip for DSLRs).
Hand Warmers are small packets containing iron powder mixed in with a few
additional chemicals such as charcoal and salt. When the packet is opened and exposed to
air, oxygen reacts with the iron (to form iron oxide - which is rust) and that reaction
releases heat. The reaction is quite slow and the heat can last anywhere from 6 to 24
hours depending on the size and design.
Since these are intended to be used to warm hands
and feet, they don't get really hot, so they are usually safe to use next to a camera.
Carrying a few extras for your hands and feet might be not be a bad idea too! If you
don't want to wrap one around your camera and you keep your camera in a bag when you're
not shooting (see "cold soaking," above), you can place a hand warmer in the bag
next to the camera. It may not raise the temperature in the bag much, but even a few
degrees can help.
Exposure
 No, I'm not talking about the medical condition (at least I hope not), but the
influence of temperature on photographic exposure. Generally it's insignificant for both
film and digital cameras. The basic sensitivities of film and digital sensors won't
change much over the temperature range that you are likely to encounter. Though cold
doesn't appreciably change intrinsic film speed, lower temperatures may significantly
lessen reciprocity failure for film so some adjustment of normal reciprocity correction
factors may be needed for long exposures.
In very snowy conditions, where just about everything is white you may need
to dial in +1 or +2 stops of exposure compensation if you want white snow to be white, and
not an 18 percent middle grey. Remember that most autoexposure systems assume the scene they are
metering is 18 percent grey and expose accordingly. Some may correct for the brightness of snow
in full sunlight when using an evaluative (matrix) metering mode, so in that case you
might not need exposure compensation. Those shooting digital should review their images
and check the image histogram to make sure that the exposure is giving the desired
results. If all else fails, you can always fall back on incident metering!
In falling or blowing snow a lens hood can help to prevent problems with snow on the
front element of a lens. Since snow tends to reflect the sky it can take on a bluish cast
on a clear, sunny day, especially in shadow areas, so a slight warming filter may help when
shooting film. Though color correction filters aren't usually necessary with digital
cameras, a UV or warming filter can be useful as a barrier against moisture with any
camera and since snow has a very high UV reflectivity (80-90) a UV filter isn't a bad
idea anyway.
Coming in from the cold
A major problem with cold weather shooting can occur not while you are outside, but
when you come back into a heated area. Very cold air is very dry, but air in a heated room
usually contains moisture. In fact, many homes use a humidifier during the winter months to keep the
air moist because it's more comfortable for people. If you bring a very cold camera and
lens into a room with warm, moist air, moisture will condense out of the air and
onto the cold surfaces. The problem isn't so much the moisture you may see on the outside
of the camera or lens, but the moisture which condenses on internal parts. Electronics and
moisture don't mix well and you really don't want condensation on the inner elements of
lenses either.
The good news is that the moisture will eventually evaporate if the equipment is
allowed to warm up to room temperature, but it can take a long time. You can gently warm
the gear with a hair drier on a low setting to speed things up, but a much better
procedure is not to let the moisture condense in the first place. If you do get
condensation on a camera, remove the batteries and don't replace them until you are sure
the camera has dried out. Just because a camera is "off" doesn't mean that
electronics are safe from damage. Many cameras are just in a "sleep" state when
off, with power still applied to some components.
You can avoid problems if you seal your camera gear in an airtight plastic bag before
you bring it inside. It will then be surrounded only by the very dry air from outdoors.
You may get some condensation on the outside of the bag, but the camera/lens will slowly
warm up in dry air inside the bag and will stay dry. Self sealing freezer bags
work well for this, but any bag which you can seal will be OK. Just be sure to put the
camera/lens in the bag before you go indoors. Once you're indoors, it's too late!
All images © 2000-2006 Bob Atkins
© 2007 Adorama
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