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OK, see that stuff on the ground in those Yellowstone winter shots posted on our site? It's snow, obviously. Snow means a lot of things to photography, and most of them are bad. The Yellowstone trip was the first really cold weather trip I'd taken with a serious photographic mission, and not surprisingly I learned a lot of interesting things. Most of my really cold experiences were with the Fuji S2, which is very vulnerable to the cold. The new Nikon D2X and D200 I've purchased seem much more forgiving, but I've yet to test it under similar conditions.
First, when the temperature gets below freezing, camera batteries die very quickly. At about 10 degrees, it's nearly impossible to keep at least some digital cameras running unless you warm the camera, the batteries, or both. Everybody has an approach to this problem, but here are the things I found were workable:
- If possible (meaning if the camera supports it and you can afford it), buy an external battery pack that links to the camera via a cable. Get a cable long enough to snake out of your clothing, and keep the battery in an inside pocket where it's warm. A videographer who accompanied me on this trip was smart and did this. I wasn't, and didn't. Next trip, I'll be using a new Quantum 2x2 power pack; more on this below.
- If you don't have a separate, warm, battery pack, keep the camera body warm when you're not shooting. Some will advocate putting it inside your clothing, but that will only work if you don't have the camera exposed long enough to get really chilled. If you do, not only will putting the camera inside your clothing be like taking an ice cube to bed, it will probably generate lots of condensation on the camera. Take care, in other words. It's probably better to hold the body, particularly the battery area, in your gloved hands while not shooting. Above all, don't leave the camera on a long lens sitting on a tripod sitting on ice! The process leaches the heat out in nothing flat, and flat is then what the batteries will be.
- Carry an extra couple of sets of batteries in a warm place, and switch them if things get cold. If the camera uses two battery types (as the S2 does) be prepared to switch both.
The battery pack strategy seems to me to be the most practical, although external batteries for digital cameras tend to be expensive. If you decide to try this approach, you'll need to contact your camera company and ask who makes a compatible battery pack. For most digital SLRs, the battery will attach via the AC adapter plug-in; that's how it works on my Fuji S2, D2X, and D200. My decision to get the Quantum 2x2 was based on inquiries to both Fuji and Quantum. I wanted a belt pack so the thing could be kept under a coat if necessary, a lot of battery life and power, and a cord long enough to snake out of the coat and attach to the camera without it being so tight it would threaten to pull a tripod over if I moved about. The 2x2 is good for about 3,000 shots if you don't use the second power connection to drive an external flash. When I got my new SB-800, I also got the cable, and when I upgrade my flash to the high-end Quantum T5, I'll get a cable for that too. I got the extension cord to be sure I had plenty of slack to move the battery pack under my coat, but the Quantum battery is rated to -40 degrees (both C and F; it's the temperature the two scales converge on) so it should be possible to keep the battery in a pocket under most conditions.
Most CF cards aren't rated to extremely cold temperatures either, though I've not had problems with cards freezing that I'm aware of. Still, my concern over this matter has prompted me to abandon microdrives in favor of the Sandisk Extreme CF cards, which are rated to well below zero F. If you plan to be outside for a protracted period at temperatures in the 20F range or lower, my personal recommendation is to get these CF cards. They're fast as heck anyway!
Another problem with photography in winter conditions is the blowing snow/ice crystals that you'll encounter. Every breeze generates a zillion tiny lens spots just looking for a place to roost, and when they hit the lens they'll likely melt to form micro water spots that you'll not see till you're processing your stuff. Keep the lens cap on, get an elastic jar cover to fit over the lens hood, or wipe the lens with a lens tissue regularly to avoid this problem. If the temperatures are fairly low (below about 25 degrees F) the chances are that snow or ice on the camera body or lens barrel won't stick. If it's warmer, you may get melting on contact with the camera, so you'll probably have to blow the stuff off continually or cover the camera with something while outside.
Changing lenses is a fact of life everywhere, and particular with digital cameras whose cost is high enough to discourage carrying multiple camera bodies. When you change a lens, you've got to take the old one off and put the new one on, obviously. Less obvious is the fact that this process will leave a hole in the bottom of the old lens, which used to stick into the camera, and will also leave a hole in the camera for the time it takes to change. All kinds of stuff will be magnetically attracted to these holes, and on entry will either gum up things or make an appearance in your subsequent pictures as blurs and specks. Try to change in a sheltered spot, and mark those rear lens covers with a dot of nail polish or something so you can see how to quickly align them on the lens. Hold the camera body with the lens side facing down when no lens is attached. One reason I went to multiple digital backs is that I could simply leave the lenses mounted; no changes means nothing gets in.
When you're ready to leave the field, put all the gear in the cases or in plastic bags and keep it there until the stuff has had a chance to warm up to room temperature, to avoid condensation. If the environment you're going into is not particularly warm and moist, you may not have a problem. To determine if you will, keep a small square of metal (stainless steel, if you have it) in a mesh compartment on the outside of your gear bags and watch that to see if stuff condenses on it when you change locations. If it does, it's not safe to remove the photo gear from the bag.
The worst condensation problems will occur if you make the serious mistake of changing lenses on a cold camera while in a warm (and even slightly humid) area. Get condensation inside the camera/lens and you'll spend a lot of time letting things dry out (during which you'll accumulate a bunch of dust motes on your CCD). If you have to change lenses, do so outdoors in a sheltered area. I've traveled with many a companion who ended up getting condensation in their cameras. All were able to dry them out by taking the batteries out, the lens off, and letting the body sit overnight. During this period, of course, all manner of dust is collecting on the CCD, so it's better to avoid condensation than to fix it.
Exposure in snowy conditions is tricky. Matrix metering on most cameras will be fooled by the preponderance of white and will usually underexpose the scene unless you compensate. Spot metering on the subject may burn the snow to pure white on the output. Look at the image or (if available) the histogram, of a test shot to check exposure. When you can't be sure, try overexposing a full stop versus the metered setting. If you use spot metering, meter on the snow and try overexposing two full stops from the reading you get. Be careful with digitals and overexposing; there's generally more latitude if you under-expose just a tad and fix it at conversion time.
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