Tips
I haven't actually photographed a tornado, but I do a lot of landscape photography of storms and lightning. Here's a few tips:
* Practice lots! Get out there and shoot everything. Get a feel for how the camera responds, and how to change settings. Also, learn how your camera focusses in different situations. When shooting storms, it can be difficult for the camera to lock on the dark storm structure, and it may lock on something else, giving you bad focus. Don't be afraid to take TONS of pictures. Digital is cheap.
* Review your shots and histogram after shooting. I have my 10D set to automatically review (w/ histogram) any shot I take. This keeps me from making silly exposure mistakes. Look for flashing highlight areas. This means that area of the shot is overexposed. Also, dark storms can really fool an automatic camera. You may find that you need to intentionally underexpose to keep the clouds dark.
* Use a high Aperature for landscapes. If you want to keep most of the scene in focus, use a higher aperature. I like to stay around F8 or so. Also, most lenses are sharper when a higher aperature is used.
* Be careful with slow shutter speeds. Unless you are shooting lightning, your shutter speeds should probably not be slower than 1/60 of a second or so. Use a higher ISO setting to get higher shutter speeds. The XT takes very clean images up to 800, and 1600 isn't really that bad. Better than having a blurry landscape where things have moved.
* Get a good, sturdy tripod. This will allow you to keep the camera steady and anchored, as well as keep your hands free.
* Consider getting a remote or intervalometer. The remote will allow you to take pictures without shaking the camera (if you are using slower shutter speeeds). An intervalometer is basically a cool remote that allows you to take repeated pictures or pictures on intervals. It's great for lightning photography.
* If you plan on doing any landscape work, get a Circular Polarizer. A polarizer will bring out the colors in most landscapes. Makes skies bluer and plants greener. Also eliminates reflections.
* Get a backup battery and extra CF cards. Don't worry too much about the faster, more expensive CF cards, unless you plan on shooting a ton of frames, and don't want to wait long while they are written. I have one of the oldest CF cards made for my 10D, and it works fine. If you find you're firing off frames and waiting for the camera to catch up, a faster one will help you more.
* Shoot in JPG while you are learning. This is a very controversial subject, and you'll get tons of opinions. Here's mine: RAW is great for certain instances, like if you are unsure of your exposure or white balance settings, but is unnecessary in most situations. Using RAW, and with time and the right software, it is possible to recover underexposed shots, and it is easier to change WB settings. RAW basically gives you the picture info straight from the camera, with nothing chnaged. With JPG, the camera is compressing the info somewhat into a JPG format, and is also applying WB, sharpening, and color settings to it (depending upon your camera settings). I use JPG 98% of the time with my 10D. It saves me a ton of space on my cards, which is a must with the way I shooting lightning. It also takes less time (IMO) and work to process later. When I shoot weddings, I use RAW exclusively.
* Learn how to use your Photo editting program. Your camera probably came with Photoshop Elements, which is what I use. It will do most of what the more expensive CS will do. I process all of my shots before printing or showing via the web. Mostly I do slight color corrections, a bit of color saturation, and sharpening.
Well, this is tons of info. Hope I didn't overwhelm you too much.
James
