The typical DSLR frame is about 2/3s the size of a 35-mm frame, reducing the field of view as shown at right.
The reduced field of view is the same as what a 35-mm camera would see if it had a lens with focal length about 1.5x the actual lens used.
Hence the term, "Focal Length Multiplier"
It is sometimes called "crop factor," but it is not a crop in the usual sense because no resolution is lost - i.e., all 6 mp are contained within the reduced frame
The FLM is considered an advantage by telephoto shooters.
Pluses and Minuses of Digital SLRs © Robert Harrington 2004