O.k so i'm just starting out and need all the help i can get. I am hoping to buy a camera and have come down to either a Pentax K20D or a Canon 500D. Here is my issue. I have no idea about mount types but i've been given a heap of lenses that are K mount. Will these fit either of these cameras? some of the lenses state for Pentax on them even though they are Tamron. Anyone used one of these cameras that can offer advise?