I'm seriously considering buying a DSLR. I have a Pentax P50 (P5 in US) from about 1986 with a couple of lenses. Would these lenses fit a Pentax *ist DL? My old P50 is manual focus and the *ist is autofocus - does this matter? From looking at various sites it seems that both cameras have "K mount" but there seems to be lots of different types of K mount. HELP ME PLEASE! Thanks.