Originally posted by Idanz0r the Tamron's price is 350$ while the pentax is 200$. I try to figure if the zoom worth the 150$.
Note, though, that the zoom is limited to f/2.8, whereas the FA50 goes to f/1.4. That can make a big difference in portraits, in terms of being able to blur backgrounds or get effects where only part of a face is in focus. That's why I said aren't necessarily better.
Quote: I also think 50mm is too short. do you have the exact model of the 70mm?
DA70/2.4 Limited is the usual name it goes by. Usually sells for around $450. It's the only 70mm lens Penax has ever made, as far as I know, and it is widely available (some of the others mentioned were discontinued many years ago).
If you can deal with manual focus - also not really a problem for portraits - there are a few older lenses that would be worth considering (available from KEH.com or via Ebay), like the M85/2 or perhaps the M100/2.8. The 90, 100, and/or 105 macro lenses from Sigma, Tamron, and/or Tokina would also be worth considering.