High-end bodies such as the 1D, 5D, and 7D series bodies are made out of magnesium alloy -- a lightweight metal casting. These bodies also tend to be weather-sealed.
Entry-range bodies such as the entire Rebel line are made out of polycarbonate plastic. The "plastic" is actually quite tough and durable -- I would not describe it as being low quality or "cheap" but it is certainly less expensive and easier to manufacture. These bodies generally do not get a weather-sealed treatment (e.g. no gaskets and o-rings at the seams and other openings.) I've seen some bodies take fairly serious whacks and suprisingly they don't show any signs of damage or body failure other than cosmetic surface scratches. So if you're afraid the body is "cheap" as in "flimsy" or "fragile" -- no, you don't have to worry nor handle your camera like it's your finest china.
In the case of the 60D, it's a polycarbonate, but it is actually weather-sealed. Keep in mind that weather-sealed does not mean weather-proof. The point of the seals is to protect the camera interior from dust and moisture -- the moisture typically being in the form of light rain, sprays and splash if you're near water, etc. It's not water-proof (don't attempt to submerge it -- not even briefly). If you get caught in the rain or get splashed, it's no big deal... just make sure you towel it dry before opening any flaps or doors. Also... most lenses are NOT weather sealed, but some are (Many of the L series lenses are weather sealed. You always have to read the specs to know.)
Tim Campbell
5D III, 5D IV, 60Da
