I had problems with the DA15, which others have also reported in the past. Hopefully, Pentax fixed their QC issues. That being said, I really liked the DA21/3.2. Unless you must have a 23mm EFL lens, I highly recommend the 21/3.2 over the 15/4, even though the lens hood for the 21/3.2 is SUPER weird and ugly looking.This is so lovely and sharp. I need a wider lens but can't decide between the 15 and the 21.