Originally posted by galaxytab The main disadvantage of the 21mm one is that it's F3.2 rather than F2.4 (and it's way more expensive).
I used to think exactly the same [why should I pay that much for a f3.2? at less give me a f2.8.] so I got a FA35 f2. however I still need more room so I went for F28 f2.8, but still need more room so I ended up with a FA20 f2.8 which all of them are a lot more expensive
. Later on I sold 28 and 35 because I like 20mm more. Then my 20 broken and I didn't want to pay that much for a used FA20 again, so I am a kind of gamble with a
DA21 just to find out that it is sharp at f3.2
I don't hesitate to use it at f3.2 at all. it even give me a nicer starburst effect (green ring version) which start from f5.6. I would be happier if Pentax make it the same size as FA20 in exchange of f2.8, FF capable & Wr but I don't really view f3.2 as a disadvantage any more. In fact, when I go compact on a trip, I go with DA21 only knowing it will do the job and do it well no matter in indoor or outdoor.
As for the price, it is more expensive than the lenses you listed above but it is a limited lens. I guess it is a give and take here.
anyway, good luck on your searching and hope you enjoy the trip.