Some years ago I bought my Pentax MZ7 with a Pentax standard zoom 28-80 f/3.5- 5.6, a cheap one but not bad at all. Now I'd like to go digital and buy a Pentax *Ist Dl or next to come K100 with standard zoom 18-55 or maybe 16-45. Can the 28-80 still be useful, considering that the only tele lens I have is an old 200 f/4 with no "A" position, very good but also limited in the usa with an AF DSLR? I don't know if it has a worthy number of lines per mm at the telelens end (80mm that should be like a 120mm on APS-C) Or should I consider buying a Pentax 50-200 a or a Tamron 70-300? And what about 18-55 vs 16-45. The first is much cheaper, is the second worth the difference in price?