Which is the best digital slr camera to buy? And how does a 300mm lense in film compare to zoom in digital?

Why would you compare a zoom lens to a 300mm fixed length lens?

If you already have a 300mm lens, just buy a DSLR that it will fit on. You will then have a 450mm if you own a Nikon or a 480mm if you own a Canon.

If you type "best digital slr" into the search field you'll be amazed to find that your question has be asked at least a 1000 times before. I suggest you read through the search results, there are plenty of suggestions there.

Digital zoom sucks. Nikon is the best camera

If you have some SPECIFIC questions to ask about one or two digital SLR's, we can help. If you tell us something about your personal level of experience, we can help. The best digital SLR for me is not the best one for you. The fact that you seem to know what a 300 mm lens is tells me that you know a little bit, but I really don't know.

A 300 mm lens is a 300 mm lens in any format. The size of the film or sensor makes the difference in it's apparent focal length, which is probably more accurately referred to as the "crop factor." It sounds like you have done some research and it has led you to think of digital zooms as being labeled in "X" terms, such as 3X or 10X. On a digital SLR, this terminology is not appropriate and it is never used. The lens is always referred to in either its true focal length or the "35 mm equivalent." In a camera with a full sized sensor (approx 35x24 mm), there is no crop factor. The image from a 300 mm lens on the full sized sensor is identical to the image on a frame of 35 mm film. The two most common crop factors are 1.5X for Nikon DSLR's and 1.6X for many Canon DSLR's. A few Canon's (the big ones) are 1.3X. Olympus DSLR's have a crop factor of 2.0X. What matters is the real focal length of the lens, but to COMPARE this between cameras of varying sensor size, the convention of 35 mm equivalent has been adopted.

Here is a mini-tutorial I made myself to compare focal lengths. This is NOT a lens test or a camera test! It is merely intended to show the difference between various focal lengths. The lens was the Nikon 18-200 VR lens, which is (by definition) an 11X lens, but that 11X does not tell you what the final image will look like. The camera was a Nikon D200 so there is a 1.5X "crop factor," "lens factor," or "focal length multiplier." There is further explanation on the image itself. It would help if you click on "All Sizes" above the image.

http://www.flickr.com/photos/7189769@N04...