Whats the best camera to use for a short film?

You mean HD. There are several cameras under $800 that do nice video, but remember you will probably want to get at the very least a tripod and maybe an external mic and some lights too. We use the Sony a33 for the film portion of the Multimedia Design class I teach. The Sony SLT cameras are great for filming because the translucent mirror allows for continuous autofocus and they also come with the ability to do a rack focus effect incredibly easily inside the camera. The a33 kit goes for about $550 right now but it is hard to find - it's replacement the a35 and the more advanced a55 are both in your price range with some change to spare.

I have to agree with you on Jim's answer. Have you considered renting a camera and lenses? You can get good results with an inexpensive camera but you need to consider lenses and also how you hold and move your camera. Most DSLRs will give you the look of film for a moderate price but that's not enough to have an overall, high quality look. I'd look at the Nikon 3100 for your budget.

DSLRs will limit you to about 15 minutes of video before they turn off to prevent the sensor from overheating. You're better off with a camcorder, such as the Canon Vixia HV40 HDV. What will look the most professional? Buying a nice camera won't make you look professional. http://shop.usa.canon.com/webapp/wcs/stores/servlet/product_10051_10051_210157_-1

The Nikon is indeed the best! You can find it way cheaper then $800 at http://bestsellingitems.squarespace.com/electronic-store/ Just give it a look, I work as an Amazon affiliator, its the best as of now and cheap price

Have you done any research on 16mm or 35mm cameras and film stock? Both are very expensive. Then there's the lighting, heaving camera support gear and the crew to run it all. You could invest up to $100,000 before every rolling a frame of film. So as you can see $800 won't come near what you'll need for a short / long film. Since it's obvious you don't understand even the terms how do you hope to produce anything at all. It's not film, it's video. It's not HP (that's a computer company) it's HD. Suggestions? Yes, learn something about this craft before you walk off and spend lots of money on equipment you obviously don't know how to use.