Brown delivers my new Pentax K20d tomorrow! I have a DA 16-45 and 50-200, which I've been using on my K10d. I don't have the $ for the new 21mm pancake. Should I wait to regenerate some more cash so I can buy the 21mm, or is an older 24mm or 28mm traditional lens a viable option? What differences in image quality/characteristics am I likely to see between these two options, with the new camera? Thanks for any ideas and knowledge you can send my way...Matt