Title basically speaks for itself: How do you protect your equipment when you are shooting in severe conditions? Rain? Severe heat/cold? Snow? Fog? ... Other? What sorts of techniques do you use to produce great-looking photography when your camera (and all the expensive lenses, too!) are exposed to the elements?
Using weather sealed camera bodies and lenses helps, but each condition has its own issues.
- Rain: in light rain you can probably get away without doing anything special, but in heavy rain, you'll need to wrap your camera in a plastic bag with an opening for the lens. Dry it off well with a towel when you get inside.
- Heat: Two separate issues... static and air conditioning. In very dry climates (like the desert) you can have static buildup. If you are using film, you might experience triboluminescent sparks which will partially expose the film. Wind slowly. Also when going in or out of air conditioning keep the lens cap on until the camera comes to ambient temperature, particularly in high humidity areas.
- Cold: Your battery life will be measured in minutes, so you might have to take along an outboard battery for longer shooting sprees. If it gets cold enough, your digital camera won't even function. If you have film, it will become brittle so wind slowly and compensate for exposure.
- Snow: Same as rain. As long as your camera is dry there is nothing to worry about. If you drop it in the snow, wipe it off with a dry towel
- Fog: Nothing really needs to be done. You'll experience the same issue as taking an air conditioned camera out in hot and humid air: condensation on the lens. Fog can produce some fantastic pictures. Wipe down the camera when you get inside, and clean the lens.
- Underwater: Get a water tight case to put your camera in. They're expensive, but open up the world of underwater photography. NOTE: test the case with paper towels on the inside first. You don't want to find out you didn't put the thing together properly with your expensive camera inside.
- Sand storm: Stay inside or put a "throwaway" UV filter on the lens. Nothing like pitted lenses due to the natural sandblasting going on.
The good news is that the professional line of cameras and lenses tend to be sealed against the weather. They can withstand dust, rain, and minor contact with water (not underwater photography though).
Use common sense. All electronics have operating conditions they are designed to work within. If you exceed those conditions (extreme hot or cold) then the sensor won't respond or will be filled with lots of noise. The good news is that most cameras have a wider range of use than you do. All mechanical and film cameras tend to be able to survive even more extreme environments (hot and cold here) than the digital counterparts, but not without their own trials. Too hot and the film will melt. Too cold and it will become brittle and break in your camera. Too dry and you have tiboluminescent streaks. Too many XRays and you have weird sine waves across your film.
If you are shooting in inclement weather, the best thing you can do is use a camera that's built for it. Canon's 1D and Nikon's D3 have weather sealing that protects the camera's circuitry. This sealing explains part of their cost. The sealing doesn't make them submersible, just resistant.
For inclement weather of the sort you often get when shooting soccer, I have a rain cover for the camera. It has three ports. One which fits with a velcro strap and vinyl sleeve to the lens, and two with drawstring vinyl covers for my hands. It makes shooting more difficult but shots of players with falling rain and flying mud are absolutely worth it. My rain hood cost AUD$100.
There is no shortage of waterproof accessories available from camera stores. Head on in armed with a fat wallet and let the sales staff fit you up.
Moderate dry Coldness is not such a problem anymore ... for the camera:
I carried my D90 in Val Thorens/Valloire (skiing resorts in France) several hours on the slopes (-20/-10 degress Celsius). Carry a spare battery, change if the one in camera becomes too cold and weak.
The problems starts when changing temperature/humidity. Enter a restaurant and you'll have your ice-cold camera covered in condensation in seconds. If you don't have a towel ready the camera won't dry before you leave, resulting in ice-frosted lens or filter. Bonus for a filter: you can remove the frozen thingy. Maybe the ziplock bag will help there.
The other problem is the one you'll have handling the camera with numb fingers. DSLR can be handled with thick gloves, but not always gripped tight enough. Be sure to carry thin undergloves.
Don't know if there were some good-looking pictures though ;)
A quick and free way is to use - wait for it - a shower cap! Use the clear ones that you get in most hotel rooms. The elastic rim keeps the plastic securely around the base of the camera so that any water falls off when it gets to the bottom rather than get onto the equipment. These things are small enough to squish into your back pocket, ready to be whipped out and put into action at the first sign of rain! If you're brave enough, shoot through the plastic for a different look!
Got me a good collection of the little boxes from hotel rooms whenever I travel and never leave home without one/two always in my kit bag! :-)
Mostly I don't bother too much unless it's a particularly inclement environment. I use good quality bodies and lenses that are designed to resist some moisture/dust/shock/heat/cold etc.
For shooting in the rain, I bought an extra lens hood for each of my lenses. Then I glued a plastic bag to each lens hood, so that I could cover the entire camera with the bag, without having to futz about with getting the lens hole just right. When I'm not using the modified lens hoods, I fold the plastic up inside them and keep them in my bag, ready for quick deployment.
If it's just lightly raining or if it is snow I don't worry about it too much. If I'm going to be out for a long time I'll use a small garbage bag with a hole cut in one end & a rubber band to hold it in place. I have also used these cheap rainsleeves; they fit better than the garbage bag & look slightly less ghetto.
Also, don't forget that cloth diapers are a great way to dry your lenses! It's probably more important to keep the front element dry than the camera body... Not because it'll cause damage but because water on the lens will distort your pictures!
If you're into DIY, maybe try this for example...
As stage photog for a outdoor music fest, I've run into a lot of inclement weather. Tyler's answer is great if you've planned ahead. Similarly, I've used the plastic bag (gallon freezer bags are excellent, as are grocery store bags) approach in an emergency by tearing a hole in the bottom and sliding it over the lens and holding it place with the lens hood. The bag opening allows space to hold the camera while keeping it dry. If the bag extends slightly into the edge of the frame. I zoom out a shade to avoid vignetting the subject.
I made a harsh-environment cover for my cameras with a baggie and an old UV filter cemented into the side of it. Works well. It even completely protected my camera when it accidentally slid off the seat of an old and leaky crab-fishing boat into a foot of water one time. When it comes time to replace the baggie from wear-'n-tear, there's no huge cost involved. When making one for yourself, put your largest camera and lens in the baggie to discern the best location to mount the filter so that all controls and viewfinder options are readily accessible through the plastic. You don't want, for example, any printing on the baggie being right over your LCD or EVF. Word of advice, few sealants and cements will adhere to the poly plastics used in sealable baggies. The only one I found to work well is a product by Loctite called Stick'n Seal.