Get a DA* 16-50mm or the 24mm f/2 without doubt. The 21mm was actually designed as a pancake style lens so you are wasting a lot of its potential. In fact the only pancake WORTH getting (they are very expensive) is the 70mm f/2.4, which isn't suitable for Halloween parties. Although I suggest the 24mm f/2 if you can find it, the DA* 16-50 (tested it) is a VERY tough lens, and I did enjoy the SDM motor and the weather sealing is a nice feature. The main advantage of the 16-50mm f/2.8 though is that it is much more versatile, and considering you already have the 50mm f/1.4. Just my thoughts.
Pentax DA* 16-50mm f/2.8
Advantages- weather sealed, popular zoom range (my opinion), SDM focusing, can be bought brand new
Pentax FA* 24mm f/2
Advantages- faster than 16-50mm,
See what really matters to you.
Hope this post helped!
16-50mm - Heard 50% plus peoples have to return there model to get right lens....lots of faulty ones...though does it do good focus for lowlight moving pictures?
so fa24 is better than da21 in every department, except focal length and size where i am more comfertable with 24mm only....
what is that af24 has which makes it do better focus except aperture 2? any tech improvement than other models? like SDM?