interesting discussion,

what's a prime?

Prime lens is a term used to denote a fixed focal length (non-zoom) lens.

example the lens on the Canon XL2 might be a 5.4mm-108mm focal length zoom. One could via an adapter use a 50mm f 1.8 Canon 35mm SLR lens ( a prime or fixed focal length lens) on the camera instead.

so prime is basically a lens that you can't use for zooming. it's focal length is "locked"?